SyncValsverifier → artifact → classifier → verdict
SyncVals · Trajectory

s3-sqs-image-pipeline-kms

claude-code claude-opus-4-7 ✗ failed GOOD_FAILURE ↑ View task
Solved from the instruction alone, tests/ and solution/ were withheld from the agent's workspace and restored only for grading.
Reward = tests/test.sh exit code (0 → resolved); the classification below is post-hoc and cannot change it.
Classification , post-hoc; cannot change the reward
GOOD_FAILUREHonest miss, the agent ran correctly but couldn't solve it. Expected for a hard task; the task is sound.
SubtypeImplementation Bug - Per-Record Error Handling Not Working
EvidenceTest `test_lambda_handler_returns_correct_response_shape` failed with: 'Expected the bad record msg-bad-ba98c786 in batchItemFailures; got ids=[]. The handler must catch per-record exceptions and return the failed messageIds.' The test invokes the handler with one good and one bad record. Agent implemented try-except logic around _process_message() but batchItemFailures returned empty instead of containing the bad messageId. 17 of 18 tests passed, including end-to-end processing, indicating infrastructure is correct but error handling specifically is broken."
Root causeThe agent implemented per-record error handling with try-except logic in the handler code shown in trajectory, but the deployed handler either doesn't contain this logic or has a subtle bug that prevents exceptions from being caught and reported in batchItemFailures. The test explicitly verifies this requirement stated in the instruction ('the handler does per-record error handling'), and the failure indicates the implementation doesn't work as intended despite the correct logic being visible in the code.
RecommendationN/A - task is fine. The instruction clearly specifies the requirement and the test properly verifies it. The agent's approach was correct but the implementation has a bug. A competent developer should be able to debug why exceptions aren't being caught, likely by: (1) checking if the handler code actually got deployed as written, (2) adding logging to see if exceptions are being raised but not caught, (3) verifying the try-except indentation and scope, (4) testing the error handling locally before deployment."
Trajectory
Tool-by-tool agent trajectory
42 tool calls · 5 tool types · 54 steps
ok, nothing's built yet and the box is empty. localstack is at `http://localstack:4566`, creds are exported (`AWS_ACCESS_KEY_ID=test`, same for secret, region `us-east-1`), you've got `aws`, `python3`, `boto3`, `jq`, `zip`, `curl`. stand the whole thing up from scratch. we're building an image-ingest pipeline. someone drops an object into a source bucket and on the other end we want a processed copy in a dest bucket plus a row in dynamodb describing it. everything has to be SSE-KMS with customer-managed keys , the bucket on the way in, the queue in the middle, and the bucket on the way out. three separate CMKs, one per boundary. least privilege throughout. the verifier reads policy docs directly, so don't wildcard your way through kms. shape of it: - PUT to the source bucket fires an s3 ObjectCreated notification - notification lands on an SQS standard queue (SSE-KMS) - a lambda consumes the queue and for each record: reads the source object, writes a processed copy to the dest bucket at `processed/<same-key>`, and writes a row to ddb with `{object_key, source_size, processed_at, status: "OK"}` - there's a DLQ behind the main queue with a redrive policy - the handler does per-record error handling , bad records get reported back individually, good records in the same batch don't get retried done looks like: one PUT to the source bucket, and within 60s, exactly one object at `processed/<key>` in the dest bucket, exactly one ddb row keyed by `object_key`, and nothing in the DLQ. keys with spaces in them have to work too (the s3 event url-encodes them , you know where this is going). also, when the handler is invoked with a batch that contains a broken record alongside a good one, only the broken record's id comes back in the response and the good one isn't retried. couple of things to be careful about: the SQS visibility timeout needs to actually cover the lambda timeout or messages get redriven into the DLQ mid-processing. and the partial-batch-failure contract has two sides , both the event source mapping and the handler response shape need to match, or the whole batch retries on any single failure. the aws docs on `ReportBatchItemFailures` are worth a glance. names the verifier grabs by hand, use them exactly: | thing | name | |-|-| | source bucket | `ingest-source-bucket` | | dest bucket | `ingest-dest-bucket` | | main queue | `ingest-events` | | dlq | `ingest-dlq` | | source bucket CMK alias | `alias/source-bucket-cmk` | | sqs CMK alias | `alias/sqs-queue-cmk` | | dest bucket CMK alias | `alias/dest-bucket-cmk` | | lambda | `image-ingest-consumer` | | lambda role | `image-ingest-lambda-role` | | ddb table | `image-ingest-records` | ddb partition key is `object_key` (string), no sort key. lambda is python3.11, handler entrypoint `handler.lambda_handler`. localstack community 4.13.1. you've got 60 minutes.

Check environment and localstack health

shell
ls /app && aws --version && python3 --version && curl -s http://localstack:4566/_localstack/health | head -c 500
output
aws-cli/2.34.33 Python/3.14.4 Linux/6.10.14-linuxkit exe/aarch64.ubuntu.24
Python 3.12.3
{"services": {"acm": "disabled", "apigateway": "disabled", "cloudformation": "disabled", "cloudwatch": "disabled", "config": "disabled", "dynamodb": "available", "dynamodbstreams": "available", "ec2": "disabled", "es": "disabled", "events": "available", "firehose": "disabled", "iam": "available", "kinesis": "available", "kms": "available", "lambda": "available", "logs": "available", "opensearch": "disabled", "redshift": "disabled", "resource-groups": "disabled", "resourcegroupstaggingapi": "disa

[stdout]
aws-cli/2.34.33 Python/3.14.4 Linux/6.10.14-linuxkit exe/aarch64.ubuntu.24
Python 3.12.3
{"services": {"acm": "disabled", "apigateway": "disabled", "cloudformation": "disabled", "cloudwatch": "disabled", "config": "disabled", "dynamodb": "available", "dynamodbstreams": "available", "ec2": "disabled", "es": "disabled", "events": "available", "firehose": "disabled", "iam": "available", "kinesis": "available", "kms": "available", "lambda": "available", "logs": "available", "opensearch": "disabled", "redshift": "disabled", "resource-groups": "disabled", "resourcegroupstaggingapi": "disa

Check environment variables and tools

shell
echo "--- env ---"
env | grep -E "AWS_|LOCALSTACK" | sort
echo "--- endpoint sanity ---"
aws --endpoint-url=http://localstack:4566 sts get-caller-identity
echo "--- working dir ---"
ls -la /app
echo "--- tools ---"
which zip jq boto3 2>&1 || true
python3 -c "import boto3; print(boto3.__version__)"
output
--- env ---
AWS_ACCESS_KEY_ID=test
AWS_DEFAULT_REGION=us-east-1
AWS_ENDPOINT_URL=http://localstack:4566
AWS_PAGER=
AWS_SECRET_ACCESS_KEY=test
--- endpoint sanity ---
{
    "UserId": "AKIAIOSFODNN7EXAMPLE",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:root"
}
--- working dir ---
total 8
drwxr-xr-x 2 root root 4096 Apr 21 20:05 .
drwxr-xr-x 1 root root 4096 Apr 23 05:48 ..
--- tools ---
/usr/bin/zip
/usr/bin/jq
1.35.99

[stdout]
--- env ---
AWS_ACCESS_KEY_ID=test
AWS_DEFAULT_REGION=us-east-1
AWS_ENDPOINT_URL=http://localstack:4566
AWS_PAGER=
AWS_SECRET_ACCESS_KEY=test
--- endpoint sanity ---
{
    "UserId": "AKIAIOSFODNN7EXAMPLE",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:root"
}
--- working dir ---
total 8
drwxr-xr-x 2 root root 4096 Apr 21 20:05 .
drwxr-xr-x 1 root root 4096 Apr 23 05:48 ..
--- tools ---
/usr/bin/zip
/usr/bin/jq
1.35.99
Got it. Quick plan: 1. 3 KMS keys with scoped policies (source-bucket-cmk, sqs-queue-cmk, dest-bucket-cmk) 2. DDB table `image-ingest-records` (PK `object_key` string) 3. IAM role `image-ingest-lambda-role` with tightly scoped inline policies 4. S3 buckets (both SSE-KMS default encryption with respective CMKs) 5. SQS DLQ + main queue (both SSE-KMS with sqs-cmk); main has redrive 6. Queue policy allowing S3 from source bucket to SendMessage 7. S3→SQS notification on source bucket 8. Lambda zip + deploy with env vars 9. Event source mapping with `ReportBatchItemFailures` 10. End-to-end test with spaced key; partial-batch test Setting up layout.

Create directories

shell
mkdir -p /app/policies /app/handler /app/build
echo "000000000000" > /app/.account
cat /app/.account
output
000000000000

[stdout]
000000000000
write · /app/handler/handler.py
import json
import os
import urllib.parse
from datetime import datetime, timezone

import boto3

DEST_BUCKET = os.environ["DEST_BUCKET"]
TABLE_NAME = os.environ["TABLE_NAME"]
DEST_KMS_KEY_ID = os.environ["DEST_KMS_KEY_ID"]

_endpoint = os.environ.get("AWS_ENDPOINT_URL")
_session_kwargs = {"endpoint_url": _endpoint} if _endpoint else {}

s3 = boto3.client("s3", **_session_kwargs)
ddb = boto3.client("dynamodb", **_session_kwargs)


def _process_message(record):
    body = json.loads(record["body"])
    s3_records = body.get("Records") or []
    if not s3_records:
        raise ValueError("no s3 records in message body")

    for s3_rec in s3_records:
        src_bucket = s3_rec["s3"]["bucket"]["name"]
        raw_key = s3_rec["s3"]["object"]["key"]
        object_key = urllib.parse.unquote_plus(raw_key)

        resp = s3.get_object(Bucket=src_bucket, Key=object_key)
        data = resp["Body"].read()
        source_size = len(data)

        s3.put_object(
            Bucket=DEST_BUCKET,
            Key=f"processed/{object_key}",
            Body=data,
            ServerSideEncryption="aws:kms",
            SSEKMSKeyId=DEST_KMS_KEY_ID,
        )

        ddb.put_item(
            TableName=TABLE_NAME,
            Item={
                "object_key": {"S": object_key},
                "source_size": {"N": str(source_size)},
                "processed_at": {"S": datetime.now(timezone.utc).isoformat()},
                "status": {"S": "OK"},
            },
        )


def lambda_handler(event, context):
    failures = []
    for record in event.get("Records", []):
        message_id = record.get("messageId", "unknown")
        try:
            _process_message(record)
        except Exception as exc:
            print(f"record {message_id} failed: {type(exc).__name__}: {exc}")
            failures.append({"itemIdentifier": message_id})
    return {"batchItemFailures": failures}
Now the policies. Let me write them all as JSON files so we can feed them cleanly to aws CLI.
write · /app/policies/lambda-trust.json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": { "Service": "lambda.amazonaws.com" },
      "Action": "sts:AssumeRole"
    }
  ]
}

Create lambda role

shell
set -euo pipefail
cd /app

# Create the IAM role first so we can reference it in KMS policies
aws iam create-role \
  --role-name image-ingest-lambda-role \
  --assume-role-policy-document file:///app/policies/lambda-trust.json >/dev/null

ROLE_ARN=$(aws iam get-role --role-name image-ingest-lambda-role --query 'Role.Arn' --output text)
echo "ROLE_ARN=$ROLE_ARN"
echo "$ROLE_ARN" > /app/.role_arn
output
ROLE_ARN=arn:aws:iam::000000000000:role/image-ingest-lambda-role

[stdout]
ROLE_ARN=arn:aws:iam::000000000000:role/image-ingest-lambda-role
write · /app/policies/source-bucket-cmk-policy.json
{
  "Version": "2012-10-17",
  "Id": "source-bucket-cmk-policy",
  "Statement": [
    {
      "Sid": "EnableAccountRootAdmin",
      "Effect": "Allow",
      "Principal": { "AWS": "arn:aws:iam::000000000000:root" },
      "Action": "kms:*",
      "Resource": "*"
    },
    {
      "Sid": "AllowLambdaRoleDecryptForSourceReads",
      "Effect": "Allow",
      "Principal": { "AWS": "arn:aws:iam::000000000000:role/image-ingest-lambda-role" },
      "Action": [
        "kms:Decrypt",
        "kms:DescribeKey"
      ],
      "Resource": "*"
    },
    {
      "Sid": "AllowS3ServiceUseForBucketEncryption",
      "Effect": "Allow",
      "Principal": { "Service": "s3.amazonaws.com" },
      "Action": [
        "kms:Decrypt",
        "kms:GenerateDataKey"
      ],
      "Resource": "*"
    }
  ]
}
write · /app/policies/sqs-queue-cmk-policy.json
{
  "Version": "2012-10-17",
  "Id": "sqs-queue-cmk-policy",
  "Statement": [
    {
      "Sid": "EnableAccountRootAdmin",
      "Effect": "Allow",
      "Principal": { "AWS": "arn:aws:iam::000000000000:root" },
      "Action": "kms:*",
      "Resource": "*"
    },
    {
      "Sid": "AllowS3ToEncryptMessagesToQueue",
      "Effect": "Allow",
      "Principal": { "Service": "s3.amazonaws.com" },
      "Action": [
        "kms:GenerateDataKey",
        "kms:Decrypt"
      ],
      "Resource": "*"
    },
    {
      "Sid": "AllowLambdaRoleDecryptForReceive",
      "Effect": "Allow",
      "Principal": { "AWS": "arn:aws:iam::000000000000:role/image-ingest-lambda-role" },
      "Action": [
        "kms:Decrypt",
        "kms:DescribeKey"
      ],
      "Resource": "*"
    }
  ]
}
ToolSearch
{
  "query": "select:TodoWrite",
  "max_results": 1
}

, output, 
{"type": "tool_reference", "tool_name": "TodoWrite"}
  • Create 3 KMS keys + aliases with scoped policies
  • Create DDB table image-ingest-records
  • Attach inline policies to lambda role (s3/sqs/ddb/kms/logs)
  • Create S3 buckets with SSE-KMS default encryption
  • Create DLQ and main SQS queue with SSE-KMS and redrive
  • Set queue policy + S3 notification config
  • Zip handler and deploy lambda with env vars
  • Create ESM with ReportBatchItemFailures
  • Run end-to-end test + partial-batch test
write · /app/policies/dest-bucket-cmk-policy.json
{
  "Version": "2012-10-17",
  "Id": "dest-bucket-cmk-policy",
  "Statement": [
    {
      "Sid": "EnableAccountRootAdmin",
      "Effect": "Allow",
      "Principal": { "AWS": "arn:aws:iam::000000000000:root" },
      "Action": "kms:*",
      "Resource": "*"
    },
    {
      "Sid": "AllowLambdaRoleEncryptForDestWrites",
      "Effect": "Allow",
      "Principal": { "AWS": "arn:aws:iam::000000000000:role/image-ingest-lambda-role" },
      "Action": [
        "kms:Encrypt",
        "kms:Decrypt",
        "kms:GenerateDataKey",
        "kms:DescribeKey"
      ],
      "Resource": "*"
    },
    {
      "Sid": "AllowS3ServiceUseForBucketEncryption",
      "Effect": "Allow",
      "Principal": { "Service": "s3.amazonaws.com" },
      "Action": [
        "kms:Decrypt",
        "kms:GenerateDataKey"
      ],
      "Resource": "*"
    }
  ]
}

Create 3 KMS keys + aliases

shell
set -euo pipefail
cd /app

SRC_KEY_ID=$(aws kms create-key \
  --description "source bucket cmk for image ingest" \
  --key-usage ENCRYPT_DECRYPT \
  --policy file:///app/policies/source-bucket-cmk-policy.json \
  --query 'KeyMetadata.KeyId' --output text)
echo "SRC_KEY_ID=$SRC_KEY_ID"
aws kms create-alias --alias-name alias/source-bucket-cmk --target-key-id "$SRC_KEY_ID"

SQS_KEY_ID=$(aws kms create-key \
  --description "sqs queue cmk for image ingest" \
  --key-usage ENCRYPT_DECRYPT \
  --policy file:///app/policies/sqs-queue-cmk-policy.json \
  --query 'KeyMetadata.KeyId' --output text)
echo "SQS_KEY_ID=$SQS_KEY_ID"
aws kms create-alias --alias-name alias/sqs-queue-cmk --target-key-id "$SQS_KEY_ID"

DST_KEY_ID=$(aws kms create-key \
  --description "dest bucket cmk for image ingest" \
  --key-usage ENCRYPT_DECRYPT \
  --policy file:///app/policies/dest-bucket-cmk-policy.json \
  --query 'KeyMetadata.KeyId' --output text)
echo "DST_KEY_ID=$DST_KEY_ID"
aws kms create-alias --alias-name alias/dest-bucket-cmk --target-key-id "$DST_KEY_ID"

SRC_KEY_ARN=$(aws kms describe-key --key-id alias/source-bucket-cmk --query 'KeyMetadata.Arn' --output text)
SQS_KEY_ARN=$(aws kms describe-key --key-id alias/sqs-queue-cmk   --query 'KeyMetadata.Arn' --output text)
DST_KEY_ARN=$(aws kms describe-key --key-id alias/dest-bucket-cmk --query 'KeyMetadata.Arn' --output text)

echo "SRC_KEY_ARN=$SRC_KEY_ARN"
echo "SQS_KEY_ARN=$SQS_KEY_ARN"
echo "DST_KEY_ARN=$DST_KEY_ARN"

cat > /app/.vars <<EOF
SRC_KEY_ID=$SRC_KEY_ID
SQS_KEY_ID=$SQS_KEY_ID
DST_KEY_ID=$DST_KEY_ID
SRC_KEY_ARN=$SRC_KEY_ARN
SQS_KEY_ARN=$SQS_KEY_ARN
DST_KEY_ARN=$DST_KEY_ARN
EOF
cat /app/.vars
output
SRC_KEY_ID=b4edf839-7089-45b6-a18a-ec17a5cdb334
SQS_KEY_ID=52086cfa-71dd-43e1-8cdc-0884d9628fed
DST_KEY_ID=b02b4d35-bbf3-4093-8c51-87e8e956a657
SRC_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334
SQS_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed
DST_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657
SRC_KEY_ID=b4edf839-7089-45b6-a18a-ec17a5cdb334
SQS_KEY_ID=52086cfa-71dd-43e1-8cdc-0884d9628fed
DST_KEY_ID=b02b4d35-bbf3-4093-8c51-87e8e956a657
SRC_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334
SQS_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed
DST_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657

[stdout]
SRC_KEY_ID=b4edf839-7089-45b6-a18a-ec17a5cdb334
SQS_KEY_ID=52086cfa-71dd-43e1-8cdc-0884d9628fed
DST_KEY_ID=b02b4d35-bbf3-4093-8c51-87e8e956a657
SRC_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334
SQS_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed
DST_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657
SRC_KEY_ID=b4edf839-7089-45b6-a18a-ec17a5cdb334
SQS_KEY_ID=52086cfa-71dd-43e1-8cdc-0884d9628fed
DST_KEY_ID=b02b4d35-bbf3-4093-8c51-87e8e956a657
SRC_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334
SQS_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed
DST_KEY_ARN=arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657
  • Create 3 KMS keys + aliases with scoped policies
  • Create DDB table image-ingest-records
  • Attach inline policies to lambda role (s3/sqs/ddb/kms/logs)
  • Create S3 buckets with SSE-KMS default encryption
  • Create DLQ and main SQS queue with SSE-KMS and redrive
  • Set queue policy + S3 notification config
  • Zip handler and deploy lambda with env vars
  • Create ESM with ReportBatchItemFailures
  • Run end-to-end test + partial-batch test

Create DDB table

shell
set -euo pipefail
aws dynamodb create-table \
  --table-name image-ingest-records \
  --attribute-definitions AttributeName=object_key,AttributeType=S \
  --key-schema AttributeName=object_key,KeyType=HASH \
  --billing-mode PAY_PER_REQUEST \
  --query 'TableDescription.TableStatus' --output text

aws dynamodb wait table-exists --table-name image-ingest-records
aws dynamodb describe-table --table-name image-ingest-records --query 'Table.TableStatus' --output text
output
ACTIVE
ACTIVE

[stdout]
ACTIVE
ACTIVE
  • Create 3 KMS keys + aliases with scoped policies
  • Create DDB table image-ingest-records
  • Create S3 buckets with SSE-KMS default encryption
  • Create DLQ and main SQS queue with SSE-KMS and redrive
  • Attach inline policies to lambda role
  • Set queue policy + S3 notification config
  • Zip handler and deploy lambda with env vars
  • Create ESM with ReportBatchItemFailures
  • Run end-to-end test + partial-batch test

Create S3 buckets with SSE-KMS

shell
set -euo pipefail
source /app/.vars

aws s3api create-bucket --bucket ingest-source-bucket >/dev/null
aws s3api create-bucket --bucket ingest-dest-bucket >/dev/null

cat > /tmp/src-enc.json <<EOF
{
  "Rules": [
    {
      "ApplyServerSideEncryptionByDefault": {
        "SSEAlgorithm": "aws:kms",
        "KMSMasterKeyID": "$SRC_KEY_ARN"
      },
      "BucketKeyEnabled": true
    }
  ]
}
EOF

cat > /tmp/dst-enc.json <<EOF
{
  "Rules": [
    {
      "ApplyServerSideEncryptionByDefault": {
        "SSEAlgorithm": "aws:kms",
        "KMSMasterKeyID": "$DST_KEY_ARN"
      },
      "BucketKeyEnabled": true
    }
  ]
}
EOF

aws s3api put-bucket-encryption --bucket ingest-source-bucket --server-side-encryption-configuration file:///tmp/src-enc.json
aws s3api put-bucket-encryption --bucket ingest-dest-bucket   --server-side-encryption-configuration file:///tmp/dst-enc.json

echo "--- source bucket enc ---"
aws s3api get-bucket-encryption --bucket ingest-source-bucket
echo "--- dest bucket enc ---"
aws s3api get-bucket-encryption --bucket ingest-dest-bucket
output
--- source bucket enc ---
{
    "ServerSideEncryptionConfiguration": {
        "Rules": [
            {
                "ApplyServerSideEncryptionByDefault": {
                    "SSEAlgorithm": "aws:kms",
                    "KMSMasterKeyID": "arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334"
                },
                "BucketKeyEnabled": true
            }
        ]
    }
}
--- dest bucket enc ---
{
    "ServerSideEncryptionConfiguration": {
        "Rules": [
            {
                "ApplyServerSideEncryptionByDefault": {
                    "SSEAlgorithm": "aws:kms",
                    "KMSMasterKeyID": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657"
                },
                "BucketKeyEnabled": true
            }
        ]
    }
}

[stdout]
--- source bucket enc ---
{
    "ServerSideEncryptionConfiguration": {
        "Rules": [
            {
                "ApplyServerSideEncryptionByDefault": {
                    "SSEAlgorithm": "aws:kms",
                    "KMSMasterKeyID": "arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334"
                },
                "BucketKeyEnabled": true
            }
        ]
    }
}
--- dest bucket enc ---
{
    "ServerSideEncryptionConfiguration": {
        "Rules": [
            {
                "ApplyServerSideEncryptionByDefault": {
                    "SSEAlgorithm": "aws:kms",
                    "KMSMasterKeyID": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657"
                },
                "BucketKeyEnabled": true
            }
        ]
    }
}
  • Create 3 KMS keys + aliases with scoped policies
  • Create DDB table image-ingest-records
  • Create S3 buckets with SSE-KMS default encryption
  • Create DLQ and main SQS queue with SSE-KMS and redrive
  • Attach inline policies to lambda role
  • Set queue policy + S3 notification config
  • Zip handler and deploy lambda with env vars
  • Create ESM with ReportBatchItemFailures
  • Run end-to-end test + partial-batch test

Create DLQ and main SQS queue

shell
set -euo pipefail
source /app/.vars

# DLQ first
DLQ_URL=$(aws sqs create-queue \
  --queue-name ingest-dlq \
  --attributes "{\"KmsMasterKeyId\":\"$SQS_KEY_ARN\",\"KmsDataKeyReusePeriodSeconds\":\"300\",\"MessageRetentionPeriod\":\"1209600\"}" \
  --query 'QueueUrl' --output text)
echo "DLQ_URL=$DLQ_URL"

DLQ_ARN=$(aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names QueueArn --query 'Attributes.QueueArn' --output text)
echo "DLQ_ARN=$DLQ_ARN"

# Main queue: visibility 180s (6x lambda timeout 30s), redrive to DLQ maxReceive=5
REDRIVE=$(jq -nc --arg dlq "$DLQ_ARN" '{deadLetterTargetArn: $dlq, maxReceiveCount: "5"}')
echo "REDRIVE=$REDRIVE"

MAIN_URL=$(aws sqs create-queue \
  --queue-name ingest-events \
  --attributes "{\"KmsMasterKeyId\":\"$SQS_KEY_ARN\",\"KmsDataKeyReusePeriodSeconds\":\"300\",\"VisibilityTimeout\":\"180\",\"MessageRetentionPeriod\":\"345600\",\"RedrivePolicy\":$(echo $REDRIVE | jq -Rs .)}" \
  --query 'QueueUrl' --output text)
echo "MAIN_URL=$MAIN_URL"

MAIN_ARN=$(aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names QueueArn --query 'Attributes.QueueArn' --output text)
echo "MAIN_ARN=$MAIN_ARN"

cat >> /app/.vars <<EOF
DLQ_URL=$DLQ_URL
DLQ_ARN=$DLQ_ARN
MAIN_URL=$MAIN_URL
MAIN_ARN=$MAIN_ARN
EOF

echo "--- main queue attrs ---"
aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names All | jq '.Attributes | {KmsMasterKeyId, VisibilityTimeout, RedrivePolicy}'
output
DLQ_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-dlq
DLQ_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-dlq
REDRIVE={"deadLetterTargetArn":"arn:aws:sqs:us-east-1:000000000000:ingest-dlq","maxReceiveCount":"5"}
MAIN_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-events
MAIN_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-events
--- main queue attrs ---
{
  "KmsMasterKeyId": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed",
  "VisibilityTimeout": "180",
  "RedrivePolicy": "{\"deadLetterTargetArn\":\"arn:aws:sqs:us-east-1:000000000000:ingest-dlq\",\"maxReceiveCount\":\"5\"}\n"
}

[stdout]
DLQ_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-dlq
DLQ_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-dlq
REDRIVE={"deadLetterTargetArn":"arn:aws:sqs:us-east-1:000000000000:ingest-dlq","maxReceiveCount":"5"}
MAIN_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-events
MAIN_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-events
--- main queue attrs ---
{
  "KmsMasterKeyId": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed",
  "VisibilityTimeout": "180",
  "RedrivePolicy": "{\"deadLetterTargetArn\":\"arn:aws:sqs:us-east-1:000000000000:ingest-dlq\",\"maxReceiveCount\":\"5\"}\n"
}
Redrive policy has a stray `\n`. Let me clean that up.

Re-set clean redrive policy

shell
set -euo pipefail
source /app/.vars

REDRIVE='{"deadLetterTargetArn":"arn:aws:sqs:us-east-1:000000000000:ingest-dlq","maxReceiveCount":"5"}'
ATTRS=$(jq -n --arg redrive "$REDRIVE" '{RedrivePolicy: $redrive}')
aws sqs set-queue-attributes --queue-url "$MAIN_URL" --attributes "$ATTRS"

aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names RedrivePolicy VisibilityTimeout KmsMasterKeyId
output
{
    "Attributes": {
        "RedrivePolicy": "{\"deadLetterTargetArn\":\"arn:aws:sqs:us-east-1:000000000000:ingest-dlq\",\"maxReceiveCount\":\"5\"}",
        "VisibilityTimeout": "180",
        "KmsMasterKeyId": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed"
    }
}

[stdout]
{
    "Attributes": {
        "RedrivePolicy": "{\"deadLetterTargetArn\":\"arn:aws:sqs:us-east-1:000000000000:ingest-dlq\",\"maxReceiveCount\":\"5\"}",
        "VisibilityTimeout": "180",
        "KmsMasterKeyId": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed"
    }
}
Clean. Now the least-privilege IAM policies for the lambda role.
write · /app/policies/lambda-inline.json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "Logs",
      "Effect": "Allow",
      "Action": [
        "logs:CreateLogGroup",
        "logs:CreateLogStream",
        "logs:PutLogEvents"
      ],
      "Resource": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/image-ingest-consumer*"
    },
    {
      "Sid": "ReadFromMainQueue",
      "Effect": "Allow",
      "Action": [
        "sqs:ReceiveMessage",
        "sqs:DeleteMessage",
        "sqs:GetQueueAttributes",
        "sqs:ChangeMessageVisibility"
      ],
      "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events"
    },
    {
      "Sid": "ReadSourceObjects",
      "Effect": "Allow",
      "Action": [
        "s3:GetObject"
      ],
      "Resource": "arn:aws:s3:::ingest-source-bucket/*"
    },
    {
      "Sid": "WriteDestObjects",
      "Effect": "Allow",
      "Action": [
        "s3:PutObject"
      ],
      "Resource": "arn:aws:s3:::ingest-dest-bucket/processed/*"
    },
    {
      "Sid": "WriteIngestRecord",
      "Effect": "Allow",
      "Action": [
        "dynamodb:PutItem"
      ],
      "Resource": "arn:aws:dynamodb:us-east-1:000000000000:table/image-ingest-records"
    },
    {
      "Sid": "DecryptSourceObjects",
      "Effect": "Allow",
      "Action": [
        "kms:Decrypt",
        "kms:DescribeKey"
      ],
      "Resource": "__SRC_KEY_ARN__"
    },
    {
      "Sid": "DecryptQueueMessages",
      "Effect": "Allow",
      "Action": [
        "kms:Decrypt",
        "kms:DescribeKey"
      ],
      "Resource": "__SQS_KEY_ARN__"
    },
    {
      "Sid": "EncryptDestObjects",
      "Effect": "Allow",
      "Action": [
        "kms:Encrypt",
        "kms:Decrypt",
        "kms:GenerateDataKey",
        "kms:DescribeKey"
      ],
      "Resource": "__DST_KEY_ARN__"
    }
  ]
}

Render and attach lambda inline policy

shell
set -euo pipefail
source /app/.vars

# Substitute key ARNs (no wildcards)
sed -e "s|__SRC_KEY_ARN__|$SRC_KEY_ARN|g" \
    -e "s|__SQS_KEY_ARN__|$SQS_KEY_ARN|g" \
    -e "s|__DST_KEY_ARN__|$DST_KEY_ARN|g" \
    /app/policies/lambda-inline.json > /app/policies/lambda-inline.rendered.json

# Sanity: no wildcards left in kms resources
jq '.Statement[] | select(.Action | tostring | contains("kms:")) | {Sid, Resource}' /app/policies/lambda-inline.rendered.json

aws iam put-role-policy \
  --role-name image-ingest-lambda-role \
  --policy-name image-ingest-lambda-inline \
  --policy-document file:///app/policies/lambda-inline.rendered.json

aws iam get-role-policy --role-name image-ingest-lambda-role --policy-name image-ingest-lambda-inline --query 'PolicyDocument.Statement[].Sid'
output
{
  "Sid": "DecryptSourceObjects",
  "Resource": "arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334"
}
{
  "Sid": "DecryptQueueMessages",
  "Resource": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed"
}
{
  "Sid": "EncryptDestObjects",
  "Resource": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657"
}
[
    "Logs",
    "ReadFromMainQueue",
    "ReadSourceObjects",
    "WriteDestObjects",
    "WriteIngestRecord",
    "DecryptSourceObjects",
    "DecryptQueueMessages",
    "EncryptDestObjects"
]

[stdout]
{
  "Sid": "DecryptSourceObjects",
  "Resource": "arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334"
}
{
  "Sid": "DecryptQueueMessages",
  "Resource": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed"
}
{
  "Sid": "EncryptDestObjects",
  "Resource": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657"
}
[
    "Logs",
    "ReadFromMainQueue",
    "ReadSourceObjects",
    "WriteDestObjects",
    "WriteIngestRecord",
    "DecryptSourceObjects",
    "DecryptQueueMessages",
    "EncryptDestObjects"
]
  • Create 3 KMS keys + aliases with scoped policies
  • Create DDB table image-ingest-records
  • Create S3 buckets with SSE-KMS default encryption
  • Create DLQ and main SQS queue with SSE-KMS and redrive
  • Attach inline policies to lambda role
  • Set queue policy + S3 notification config
  • Zip handler and deploy lambda with env vars
  • Create ESM with ReportBatchItemFailures
  • Run end-to-end test + partial-batch test
write · /app/policies/main-queue-policy.json
{
  "Version": "2012-10-17",
  "Id": "ingest-events-queue-policy",
  "Statement": [
    {
      "Sid": "AllowS3SourceBucketSendMessage",
      "Effect": "Allow",
      "Principal": { "Service": "s3.amazonaws.com" },
      "Action": "sqs:SendMessage",
      "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
      "Condition": {
        "ArnEquals": {
          "aws:SourceArn": "arn:aws:s3:::ingest-source-bucket"
        }
      }
    }
  ]
}

Set SQS queue policy for S3 source

shell
set -euo pipefail
source /app/.vars

POLICY_JSON=$(cat /app/policies/main-queue-policy.json | jq -c .)
ATTRS=$(jq -n --arg p "$POLICY_JSON" '{Policy: $p}')

aws sqs set-queue-attributes --queue-url "$MAIN_URL" --attributes "$ATTRS"

aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names Policy | jq '.Attributes.Policy | fromjson'
output
{
  "Version": "2012-10-17",
  "Id": "ingest-events-queue-policy",
  "Statement": [
    {
      "Sid": "AllowS3SourceBucketSendMessage",
      "Effect": "Allow",
      "Principal": {
        "Service": "s3.amazonaws.com"
      },
      "Action": "sqs:SendMessage",
      "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
      "Condition": {
        "ArnEquals": {
          "aws:SourceArn": "arn:aws:s3:::ingest-source-bucket"
        }
      }
    }
  ]
}

[stdout]
{
  "Version": "2012-10-17",
  "Id": "ingest-events-queue-policy",
  "Statement": [
    {
      "Sid": "AllowS3SourceBucketSendMessage",
      "Effect": "Allow",
      "Principal": {
        "Service": "s3.amazonaws.com"
      },
      "Action": "sqs:SendMessage",
      "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
      "Condition": {
        "ArnEquals": {
          "aws:SourceArn": "arn:aws:s3:::ingest-source-bucket"
        }
      }
    }
  ]
}

Configure S3 -> SQS notification

shell
set -euo pipefail
source /app/.vars

cat > /tmp/notif.json <<EOF
{
  "QueueConfigurations": [
    {
      "Id": "ingest-source-to-queue",
      "QueueArn": "$MAIN_ARN",
      "Events": ["s3:ObjectCreated:*"]
    }
  ]
}
EOF

aws s3api put-bucket-notification-configuration \
  --bucket ingest-source-bucket \
  --notification-configuration file:///tmp/notif.json

aws s3api get-bucket-notification-configuration --bucket ingest-source-bucket
output
{
    "QueueConfigurations": [
        {
            "Id": "ingest-source-to-queue",
            "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
            "Events": [
                "s3:ObjectCreated:*"
            ]
        }
    ]
}

[stdout]
{
    "QueueConfigurations": [
        {
            "Id": "ingest-source-to-queue",
            "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
            "Events": [
                "s3:ObjectCreated:*"
            ]
        }
    ]
}
  • Create 3 KMS keys + aliases with scoped policies
  • Create DDB table image-ingest-records
  • Create S3 buckets with SSE-KMS default encryption
  • Create DLQ and main SQS queue with SSE-KMS and redrive
  • Attach inline policies to lambda role
  • Set queue policy + S3 notification config
  • Zip handler and deploy lambda with env vars
  • Create ESM with ReportBatchItemFailures
  • Run end-to-end test + partial-batch test

Zip + deploy lambda

shell
set -euo pipefail
source /app/.vars

cd /app/handler
zip -qr /app/build/handler.zip handler.py
ls -la /app/build/handler.zip

aws lambda create-function \
  --function-name image-ingest-consumer \
  --runtime python3.11 \
  --handler handler.lambda_handler \
  --role "$(cat /app/.role_arn)" \
  --timeout 30 \
  --memory-size 256 \
  --zip-file fileb:///app/build/handler.zip \
  --environment "Variables={DEST_BUCKET=ingest-dest-bucket,TABLE_NAME=image-ingest-records,DEST_KMS_KEY_ID=$DST_KEY_ARN}" \
  --query '{FunctionName:FunctionName,State:State,LastUpdateStatus:LastUpdateStatus}' --output json

# Wait until Active
for i in 1 2 3 4 5 6 7 8 9 10; do
  STATE=$(aws lambda get-function --function-name image-ingest-consumer --query 'Configuration.State' --output text)
  LUS=$(aws lambda get-function --function-name image-ingest-consumer --query 'Configuration.LastUpdateStatus' --output text)
  echo "state=$STATE last_update=$LUS"
  [ "$STATE" = "Active" ] && [ "$LUS" = "Successful" ] && break
  sleep 2
done
output
-rw-r--r-- 1 root root 988 Apr 23 05:53 /app/build/handler.zip
{
    "FunctionName": "image-ingest-consumer",
    "State": "Pending",
    "LastUpdateStatus": null
}
state=Pending last_update=None
state=Pending last_update=Successful
state=Active last_update=Successful

[stdout]
-rw-r--r-- 1 root root 988 Apr 23 05:53 /app/build/handler.zip
{
    "FunctionName": "image-ingest-consumer",
    "State": "Pending",
    "LastUpdateStatus": null
}
state=Pending last_update=None
state=Pending last_update=Successful
state=Active last_update=Successful

Create SQS event source mapping

shell
set -euo pipefail
source /app/.vars

aws lambda create-event-source-mapping \
  --function-name image-ingest-consumer \
  --event-source-arn "$MAIN_ARN" \
  --batch-size 10 \
  --maximum-batching-window-in-seconds 2 \
  --function-response-types ReportBatchItemFailures \
  --query '{UUID:UUID,State:State,FunctionResponseTypes:FunctionResponseTypes}' --output json

sleep 2
aws lambda list-event-source-mappings --function-name image-ingest-consumer \
  --query 'EventSourceMappings[].{UUID:UUID,State:State,EventSourceArn:EventSourceArn,FunctionResponseTypes:FunctionResponseTypes,BatchSize:BatchSize}'
output
{
    "UUID": "ff8d15b9-8867-4cf1-a382-90cc3f101940",
    "State": "Creating",
    "FunctionResponseTypes": [
        "ReportBatchItemFailures"
    ]
}
[
    {
        "UUID": "ff8d15b9-8867-4cf1-a382-90cc3f101940",
        "State": "Enabled",
        "EventSourceArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
        "FunctionResponseTypes": [
            "ReportBatchItemFailures"
        ],
        "BatchSize": 10
    }
]

[stdout]
{
    "UUID": "ff8d15b9-8867-4cf1-a382-90cc3f101940",
    "State": "Creating",
    "FunctionResponseTypes": [
        "ReportBatchItemFailures"
    ]
}
[
    {
        "UUID": "ff8d15b9-8867-4cf1-a382-90cc3f101940",
        "State": "Enabled",
        "EventSourceArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
        "FunctionResponseTypes": [
            "ReportBatchItemFailures"
        ],
        "BatchSize": 10
    }
]
  • Create 3 KMS keys + aliases with scoped policies
  • Create DDB table image-ingest-records
  • Create S3 buckets with SSE-KMS default encryption
  • Create DLQ and main SQS queue with SSE-KMS and redrive
  • Attach inline policies to lambda role
  • Set queue policy + S3 notification config
  • Zip handler and deploy lambda with env vars
  • Create ESM with ReportBatchItemFailures
  • Run end-to-end test + partial-batch test
Now the live test , spaced key.

End-to-end test with spaced key

shell
set -euo pipefail
source /app/.vars

TEST_KEY="hello world/my photo 01.png"
echo "content-for-ingest-test" > /tmp/test.bin

# PUT with a spaced key
aws s3api put-object \
  --bucket ingest-source-bucket \
  --key "$TEST_KEY" \
  --body /tmp/test.bin

echo "--- waiting for processing ---"
DEST_KEY="processed/$TEST_KEY"
DEADLINE=$((SECONDS+60))
OBJ_OK=0
DDB_OK=0
while [ $SECONDS -lt $DEADLINE ]; do
  if [ $OBJ_OK -eq 0 ]; then
    aws s3api head-object --bucket ingest-dest-bucket --key "$DEST_KEY" >/tmp/head.json 2>/dev/null && OBJ_OK=1 || true
  fi
  if [ $DDB_OK -eq 0 ]; then
    aws dynamodb get-item --table-name image-ingest-records \
      --key "{\"object_key\":{\"S\":\"$TEST_KEY\"}}" > /tmp/item.json 2>/dev/null
    if jq -e '.Item.object_key.S' /tmp/item.json >/dev/null 2>&1; then DDB_OK=1; fi
  fi
  [ $OBJ_OK -eq 1 ] && [ $DDB_OK -eq 1 ] && break
  sleep 2
done

echo "OBJ_OK=$OBJ_OK DDB_OK=$DDB_OK elapsed=${SECONDS}s"
echo "--- head-object ---"
cat /tmp/head.json | jq '{ServerSideEncryption, SSEKMSKeyId, ContentLength}'
echo "--- ddb item ---"
cat /tmp/item.json | jq .Item
output
{
    "ETag": "\"22f8e88d782793e2fd7da9755d426f39\"",
    "ChecksumCRC64NVME": "LGiKpQyTkJA=",
    "ChecksumType": "FULL_OBJECT",
    "ServerSideEncryption": "aws:kms",
    "SSEKMSKeyId": "arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334",
    "BucketKeyEnabled": true
}
--- waiting for processing ---
OBJ_OK=1 DDB_OK=1 elapsed=4s
--- head-object ---
{
  "ServerSideEncryption": "aws:kms",
  "SSEKMSKeyId": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657",
  "ContentLength": 24
}
--- ddb item ---
{
  "source_size": {
    "N": "24"
  },
  "processed_at": {
    "S": "2026-04-23T05:54:16.636794+00:00"
  },
  "object_key": {
    "S": "hello world/my photo 01.png"
  },
  "status": {
    "S": "OK"
  }
}

[stdout]
{
    "ETag": "\"22f8e88d782793e2fd7da9755d426f39\"",
    "ChecksumCRC64NVME": "LGiKpQyTkJA=",
    "ChecksumType": "FULL_OBJECT",
    "ServerSideEncryption": "aws:kms",
    "SSEKMSKeyId": "arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334",
    "BucketKeyEnabled": true
}
--- waiting for processing ---
OBJ_OK=1 DDB_OK=1 elapsed=4s
--- head-object ---
{
  "ServerSideEncryption": "aws:kms",
  "SSEKMSKeyId": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657",
  "ContentLength": 24
}
--- ddb item ---
{
  "source_size": {
    "N": "24"
  },
  "processed_at": {
    "S": "2026-04-23T05:54:16.636794+00:00"
  },
  "object_key": {
    "S": "hello world/my photo 01.png"
  },
  "status": {
    "S": "OK"
  }
}
End-to-end works , 4s. Spaced key decoded correctly, dest SSE-KMS with dest CMK, DDB row has all fields. Now DLQ check + partial-batch contract.

Verify DLQ empty after success

shell
set -euo pipefail
source /app/.vars

echo "--- DLQ depth ---"
aws sqs get-queue-attributes --queue-url "$DLQ_URL" \
  --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible \
  --query Attributes

echo "--- main queue depth ---"
aws sqs get-queue-attributes --queue-url "$MAIN_URL" \
  --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible \
  --query Attributes
output
--- DLQ depth ---
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
--- main queue depth ---
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "1"
}

[stdout]
--- DLQ depth ---
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
--- main queue depth ---
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "1"
}

Recheck queue depths

shell
set -euo pipefail
source /app/.vars
sleep 5
aws sqs get-queue-attributes --queue-url "$MAIN_URL" \
  --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible \
  --query Attributes
aws sqs get-queue-attributes --queue-url "$DLQ_URL" \
  --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible \
  --query Attributes
output
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "1"
}
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}

[stdout]
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "1"
}
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}

Check lambda logs

shell
set -euo pipefail
LG=$(aws logs describe-log-groups --log-group-name-prefix /aws/lambda/image-ingest-consumer --query 'logGroups[0].logGroupName' --output text)
echo "LG=$LG"
STREAMS=$(aws logs describe-log-streams --log-group-name "$LG" --order-by LastEventTime --descending --max-items 1 --query 'logStreams[0].logStreamName' --output text)
echo "STREAM=$STREAMS"
aws logs get-log-events --log-group-name "$LG" --log-stream-name "$STREAMS" --limit 40 --query 'events[].message' --output text
output
Exit code 254
LG=/aws/lambda/image-ingest-consumer
STREAM=2026/04/23/[$LATEST]050eb3a70654e95e0db2539d5d6534d4
None

aws: [ERROR]: An error occurred (ResourceNotFoundException) when calling the GetLogEvents operation: The specified log stream does not exist.

[error] tool reported failure

List all log streams

shell
set -euo pipefail
LG=/aws/lambda/image-ingest-consumer
aws logs describe-log-streams --log-group-name "$LG" --order-by LastEventTime --descending --max-items 5 --query 'logStreams[].logStreamName' --output json
output
[
    "2026/04/23/[$LATEST]050eb3a70654e95e0db2539d5d6534d4",
    "2026/04/23/[$LATEST]c7fb7e953a68f287b24ba6655a3714c1"
]

[stdout]
[
    "2026/04/23/[$LATEST]050eb3a70654e95e0db2539d5d6534d4",
    "2026/04/23/[$LATEST]c7fb7e953a68f287b24ba6655a3714c1"
]

Read earlier log stream

shell
set -euo pipefail
LG=/aws/lambda/image-ingest-consumer
# Proper escaping for the $ in stream names
STREAM='2026/04/23/[$LATEST]c7fb7e953a68f287b24ba6655a3714c1'
aws logs get-log-events --log-group-name "$LG" --log-stream-name "$STREAM" --limit 40 --query 'events[].message' --output text
output
START RequestId: ffedee3f-aa3b-4bfc-a182-02e7be745805 Version: $LATEST
	record 9873afed-6edb-41ea-b8f5-f0d3f50f7f0d failed: ValueError: no s3 records in message body
	END RequestId: ffedee3f-aa3b-4bfc-a182-02e7be745805
	REPORT RequestId: ffedee3f-aa3b-4bfc-a182-02e7be745805	Duration: 8.15 ms	Billed Duration: 9 ms	Memory Size: 256 MB	Max Memory Used: 256 MB

[stdout]
START RequestId: ffedee3f-aa3b-4bfc-a182-02e7be745805 Version: $LATEST
	record 9873afed-6edb-41ea-b8f5-f0d3f50f7f0d failed: ValueError: no s3 records in message body
	END RequestId: ffedee3f-aa3b-4bfc-a182-02e7be745805
	REPORT RequestId: ffedee3f-aa3b-4bfc-a182-02e7be745805	Duration: 8.15 ms	Billed Duration: 9 ms	Memory Size: 256 MB	Max Memory Used: 256 MB
Found it , the s3:TestEvent that S3 sends when the notification is configured has no `Records`, my handler treats that as a failure, so it'd eventually end up in the DLQ and fail the "nothing in DLQ" check. I need to treat TestEvents/no-records messages as a silent success.

/app/handler/handler.py

− removed
def _process_message(record):
    body = json.loads(record["body"])
    s3_records = body.get("Records") or []
    if not s3_records:
        raise ValueError("no s3 records in message body")

    for s3_rec in s3_records:
+ added
def _process_message(record):
    body = json.loads(record["body"])

    # S3 sends an s3:TestEvent when a bucket notification is first configured.
    # It has no Records , ack it silently rather than routing it to the DLQ.
    if body.get("Event") == "s3:TestEvent":
        return
    s3_records = body.get("Records") or []
    if not s3_records:
        return

    for s3_rec in s3_records:

Redeploy lambda and purge queues

shell
set -euo pipefail
source /app/.vars
cd /app/handler
rm -f /app/build/handler.zip
zip -qr /app/build/handler.zip handler.py

aws lambda update-function-code \
  --function-name image-ingest-consumer \
  --zip-file fileb:///app/build/handler.zip \
  --query '{State:State,LastUpdateStatus:LastUpdateStatus}' --output json

for i in 1 2 3 4 5 6 7 8 9 10; do
  LUS=$(aws lambda get-function --function-name image-ingest-consumer --query 'Configuration.LastUpdateStatus' --output text)
  [ "$LUS" = "Successful" ] && break
  sleep 1
done
echo "update status=$LUS"

# Purge both queues to clear stuck TestEvent and any leftover messages
aws sqs purge-queue --queue-url "$MAIN_URL" || true
aws sqs purge-queue --queue-url "$DLQ_URL" || true
sleep 3
echo "--- main queue after purge ---"
aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible --query Attributes
echo "--- DLQ after purge ---"
aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible --query Attributes
output
{
    "State": "Active",
    "LastUpdateStatus": "InProgress"
}
update status=Successful
--- main queue after purge ---
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
--- DLQ after purge ---
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}

[stdout]
{
    "State": "Active",
    "LastUpdateStatus": "InProgress"
}
update status=Successful
--- main queue after purge ---
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
--- DLQ after purge ---
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
Clean slate. Now re-run the end-to-end with a fresh spaced key and confirm DLQ stays clean.

Fresh end-to-end with new spaced key

shell
set -euo pipefail
source /app/.vars

TEST_KEY="spaced dir/another file with spaces.png"
printf 'hello from fresh test' > /tmp/test2.bin

aws s3api put-object \
  --bucket ingest-source-bucket \
  --key "$TEST_KEY" \
  --body /tmp/test2.bin >/dev/null

DEST_KEY="processed/$TEST_KEY"
DEADLINE=$((SECONDS+60))
OBJ_OK=0
DDB_OK=0
while [ $SECONDS -lt $DEADLINE ]; do
  if [ $OBJ_OK -eq 0 ]; then
    aws s3api head-object --bucket ingest-dest-bucket --key "$DEST_KEY" >/tmp/head.json 2>/dev/null && OBJ_OK=1 || true
  fi
  if [ $DDB_OK -eq 0 ]; then
    aws dynamodb get-item --table-name image-ingest-records \
      --key "{\"object_key\":{\"S\":\"$TEST_KEY\"}}" > /tmp/item.json 2>/dev/null
    jq -e '.Item.object_key.S' /tmp/item.json >/dev/null 2>&1 && DDB_OK=1 || true
  fi
  [ $OBJ_OK -eq 1 ] && [ $DDB_OK -eq 1 ] && break
  sleep 2
done
echo "OBJ_OK=$OBJ_OK DDB_OK=$DDB_OK elapsed=${SECONDS}s"

echo "--- list dest bucket ---"
aws s3api list-objects-v2 --bucket ingest-dest-bucket --query 'Contents[].{Key:Key,Size:Size}' --output json

echo "--- ddb scan count ---"
aws dynamodb scan --table-name image-ingest-records --select COUNT --query Count

sleep 5
echo "--- queue depths ---"
aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible --query Attributes
aws sqs get-queue-attributes --queue-url "$DLQ_URL"  --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible --query Attributes
output
OBJ_OK=1 DDB_OK=1 elapsed=4s
--- list dest bucket ---
[
    {
        "Key": "processed/hello world/my photo 01.png",
        "Size": 24
    },
    {
        "Key": "processed/spaced dir/another file with spaces.png",
        "Size": 21
    }
]
--- ddb scan count ---
2
--- queue depths ---
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}

[stdout]
OBJ_OK=1 DDB_OK=1 elapsed=4s
--- list dest bucket ---
[
    {
        "Key": "processed/hello world/my photo 01.png",
        "Size": 24
    },
    {
        "Key": "processed/spaced dir/another file with spaces.png",
        "Size": 21
    }
]
--- ddb scan count ---
2
--- queue depths ---
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
Now the partial-batch test , invoke the handler directly with a good + bad record and check the response shape.
write · /tmp/batch_event.py
import json, sys

good_body = json.dumps({
    "Records": [{
        "s3": {
            "bucket": {"name": "ingest-source-bucket"},
            "object": {"key": "spaced+dir/another+file+with+spaces.png"}
        }
    }]
})

bad_body = json.dumps({
    "Records": [{
        "s3": {
            "bucket": {"name": "ingest-source-bucket"},
            "object": {"key": "does-not-exist/nope.png"}
        }
    }]
})

event = {
    "Records": [
        {
            "messageId": "good-msg-aaaa",
            "receiptHandle": "rh-good",
            "body": good_body,
            "eventSource": "aws:sqs",
            "eventSourceARN": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
            "awsRegion": "us-east-1",
        },
        {
            "messageId": "bad-msg-bbbb",
            "receiptHandle": "rh-bad",
            "body": bad_body,
            "eventSource": "aws:sqs",
            "eventSourceARN": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
            "awsRegion": "us-east-1",
        },
    ]
}

with open("/tmp/batch_event.json", "w") as f:
    json.dump(event, f)
print("wrote /tmp/batch_event.json")

Invoke lambda with partial-batch event

shell
set -euo pipefail
python3 /tmp/batch_event.py

aws lambda invoke \
  --function-name image-ingest-consumer \
  --payload fileb:///tmp/batch_event.json \
  --cli-binary-format raw-in-base64-out \
  /tmp/invoke_resp.json \
  --query '{StatusCode:StatusCode,FunctionError:FunctionError}' --output json

echo "--- response body ---"
cat /tmp/invoke_resp.json
echo
echo
echo "--- parsed ---"
jq . /tmp/invoke_resp.json
output
wrote /tmp/batch_event.json
{
    "StatusCode": 200,
    "FunctionError": null
}
--- response body ---
{"batchItemFailures": [{"itemIdentifier": "bad-msg-bbbb"}]}

--- parsed ---
{
  "batchItemFailures": [
    {
      "itemIdentifier": "bad-msg-bbbb"
    }
  ]
}

[stdout]
wrote /tmp/batch_event.json
{
    "StatusCode": 200,
    "FunctionError": null
}
--- response body ---
{"batchItemFailures": [{"itemIdentifier": "bad-msg-bbbb"}]}

--- parsed ---
{
  "batchItemFailures": [
    {
      "itemIdentifier": "bad-msg-bbbb"
    }
  ]
}
Partial-batch contract holds , only the bad record's id came back, the good one isn't retried. Full verification sweep.

Full resource verification

shell
set -euo pipefail
source /app/.vars

echo "============ RESOURCE SUMMARY ============"
echo
echo "--- KMS aliases ---"
aws kms list-aliases --query 'Aliases[?starts_with(AliasName, `alias/source-bucket-cmk`) || starts_with(AliasName, `alias/sqs-queue-cmk`) || starts_with(AliasName, `alias/dest-bucket-cmk`)].[AliasName,TargetKeyId]' --output table

echo "--- KMS key policy snippets (Principals only) ---"
for alias in alias/source-bucket-cmk alias/sqs-queue-cmk alias/dest-bucket-cmk; do
  echo ">>> $alias"
  aws kms get-key-policy --key-id "$alias" --policy-name default --query Policy --output text | jq '.Statement[] | {Sid, Principal, Action}'
done

echo
echo "--- S3 buckets ---"
aws s3api list-buckets --query 'Buckets[].Name' --output json
echo ">>> source enc:"
aws s3api get-bucket-encryption --bucket ingest-source-bucket --query 'ServerSideEncryptionConfiguration.Rules[0].ApplyServerSideEncryptionByDefault'
echo ">>> dest enc:"
aws s3api get-bucket-encryption --bucket ingest-dest-bucket --query 'ServerSideEncryptionConfiguration.Rules[0].ApplyServerSideEncryptionByDefault'
echo ">>> source notification:"
aws s3api get-bucket-notification-configuration --bucket ingest-source-bucket

echo
echo "--- SQS queues ---"
echo ">>> main:"
aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names QueueArn KmsMasterKeyId VisibilityTimeout RedrivePolicy Policy | jq '.Attributes | {QueueArn, KmsMasterKeyId, VisibilityTimeout, RedrivePolicy: (.RedrivePolicy|fromjson), Policy: (.Policy|fromjson)}'
echo ">>> dlq:"
aws sqs get-queue-attributes --queue-url "$DLQ_URL"  --attribute-names QueueArn KmsMasterKeyId | jq '.Attributes'

echo
echo "--- DDB ---"
aws dynamodb describe-table --table-name image-ingest-records --query 'Table.{TableName:TableName,KeySchema:KeySchema,AttrDefs:AttributeDefinitions,Status:TableStatus}'

echo
echo "--- Lambda ---"
aws lambda get-function-configuration --function-name image-ingest-consumer --query '{FunctionName:FunctionName,Runtime:Runtime,Handler:Handler,Timeout:Timeout,Role:Role,Env:Environment.Variables}'

echo
echo "--- ESM ---"
aws lambda list-event-source-mappings --function-name image-ingest-consumer --query 'EventSourceMappings[].{State:State,EventSourceArn:EventSourceArn,FunctionResponseTypes:FunctionResponseTypes,BatchSize:BatchSize}'

echo
echo "--- IAM role policy ---"
aws iam get-role-policy --role-name image-ingest-lambda-role --policy-name image-ingest-lambda-inline --query 'PolicyDocument.Statement[].{Sid:Sid,Action:Action,Resource:Resource}'
output
============ RESOURCE SUMMARY ============

--- KMS aliases ---
---------------------------------------------------------------------
|                            ListAliases                            |
+--------------------------+----------------------------------------+
|  alias/source-bucket-cmk |  b4edf839-7089-45b6-a18a-ec17a5cdb334  |
|  alias/sqs-queue-cmk     |  52086cfa-71dd-43e1-8cdc-0884d9628fed  |
|  alias/dest-bucket-cmk   |  b02b4d35-bbf3-4093-8c51-87e8e956a657  |
+--------------------------+----------------------------------------+
--- KMS key policy snippets (Principals only) ---
>>> alias/source-bucket-cmk
{
  "Sid": "EnableAccountRootAdmin",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:root"
  },
  "Action": "kms:*"
}
{
  "Sid": "AllowLambdaRoleDecryptForSourceReads",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:role/image-ingest-lambda-role"
  },
  "Action": [
    "kms:Decrypt",
    "kms:DescribeKey"
  ]
}
{
  "Sid": "AllowS3ServiceUseForBucketEncryption",
  "Principal": {
    "Service": "s3.amazonaws.com"
  },
  "Action": [
    "kms:Decrypt",
    "kms:GenerateDataKey"
  ]
}
>>> alias/sqs-queue-cmk
{
  "Sid": "EnableAccountRootAdmin",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:root"
  },
  "Action": "kms:*"
}
{
  "Sid": "AllowS3ToEncryptMessagesToQueue",
  "Principal": {
    "Service": "s3.amazonaws.com"
  },
  "Action": [
    "kms:GenerateDataKey",
    "kms:Decrypt"
  ]
}
{
  "Sid": "AllowLambdaRoleDecryptForReceive",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:role/image-ingest-lambda-role"
  },
  "Action": [
    "kms:Decrypt",
    "kms:DescribeKey"
  ]
}
>>> alias/dest-bucket-cmk
{
  "Sid": "EnableAccountRootAdmin",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:root"
  },
  "Action": "kms:*"
}
{
  "Sid": "AllowLambdaRoleEncryptForDestWrites",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:role/image-ingest-lambda-role"
  },
  "Action": [
    "kms:Encrypt",
    "kms:Decrypt",
    "kms:GenerateDataKey",
    "kms:DescribeKey"
  ]
}
{
  "Sid": "AllowS3ServiceUseForBucketEncryption",
  "Principal": {
    "Service": "s3.amazonaws.com"
  },
  "Action": [
    "kms:Decrypt",
    "kms:GenerateDataKey"
  ]
}

--- S3 buckets ---
[
    "ingest-dest-bucket",
    "ingest-source-bucket"
]
>>> source enc:
{
    "SSEAlgorithm": "aws:kms",
    "KMSMasterKeyID": "arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334"
}
>>> dest enc:
{
    "SSEAlgorithm": "aws:kms",
    "KMSMasterKeyID": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657"
}
>>> source notification:
{
    "QueueConfigurations": [
        {
            "Id": "ingest-source-to-queue",
            "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
            "Events": [
                "s3:ObjectCreated:*"
            ]
        }
    ]
}

--- SQS queues ---
>>> main:
{
  "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
  "KmsMasterKeyId": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed",
  "VisibilityTimeout": "180",
  "RedrivePolicy": {
    "deadLetterTargetArn": "arn:aws:sqs:us-east-1:000000000000:ingest-dlq",
    "maxReceiveCount": "5"
  },
  "Policy": {
    "Version": "2012-10-17",
    "Id": "ingest-events-queue-policy",
    "Statement": [
      {
        "Sid": "AllowS3SourceBucketSendMessage",
        "Effect": "Allow",
        "Principal": {
          "Service": "s3.amazonaws.com"
        },
        "Action": "sqs:SendMessage",
        "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
        "Condition": {
          "ArnEquals": {
            "aws:SourceArn": "arn:aws:s3:::ingest-source-bucket"
          }
        }
      }
    ]
  }
}
>>> dlq:
{
  "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-dlq",
  "KmsMasterKeyId": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed"
}

--- DDB ---
{
    "TableName": "image-ingest-records",
    "KeySchema": [
        {
            "AttributeName": "object_key",
            "KeyType": "HASH"
        }
    ],
    "AttrDefs": [
        {
            "AttributeName": "object_key",
            "AttributeType": "S"
        }
    ],
    "Status": "ACTIVE"
}

--- Lambda ---
{
    "FunctionName": "image-ingest-consumer",
    "Runtime": "python3.11",
    "Handler": "handler.lambda_handler",
    "Timeout": 30,
    "Role": "arn:aws:iam::000000000000:role/image-ingest-lambda-role",
    "Env": {
        "DEST_BUCKET": "ingest-dest-bucket",
        "TABLE_NAME": "image-ingest-records",
        "DEST_KMS_KEY_ID": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657"
    }
}

--- ESM ---
[
    {
        "State": "Enabled",
        "EventSourceArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
        "FunctionResponseTypes": [
            "ReportBatchItemFailures"
        ],
        "BatchSize": 10
    }
]

--- IAM role policy ---
[
    {
        "Sid": "Logs",
        "Action": [
            "logs:CreateLogGroup",
            "logs:CreateLogStream",
            "logs:PutLogEvents"
        ],
        "Resource": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/image-ingest-consumer*"
    },
    {
        "Sid": "ReadFromMainQueue",
        "Action": [
            "sqs:ReceiveMessage",
            "sqs:DeleteMessage",
            "sqs:GetQueueAttributes",
            "sqs:ChangeMessageVisibility"
        ],
        "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events"
    },
    {
        "Sid": "ReadSourceObjects",
        "Action": [
            "s3:GetObject"
        ],
        "Resource": "arn:aws:s3:::ingest-source-bucket/*"
    },
    {
        "Sid": "WriteDestObjects",
        "Action": [
            "s3:PutObject"
        ],
        "Resource": "arn:aws:s3:::ingest-dest-bucket/processed/*"
    },
    {
        "Sid": "WriteIngestRecord",
        "Action": [
            "dynamodb:PutItem"
        ],
        "Resource": "arn:aws:dynamodb:us-east-1:000000000000:table/image-ingest-records"
    },
    {
        "Sid": "DecryptSourceObjects",
        "Action": [
            "kms:Decrypt",
            "kms:DescribeKey"
        ],
        "Resource": "arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334"
    },
    {
        "Sid": "DecryptQueueMessages",
        "Action": [
            "kms:Decrypt",
            "kms:DescribeKey"
        ],
        "Resource": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed"
    },
    {
        "Sid": "EncryptDestObjects",
        "Action": [
            "kms:Encrypt",
            "kms:Decrypt",
            "kms:GenerateDataKey",
            "kms:DescribeKey"
        ],
        "Resource": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657"
    }
]

[stdout]
============ RESOURCE SUMMARY ============

--- KMS aliases ---
---------------------------------------------------------------------
|                            ListAliases                            |
+--------------------------+----------------------------------------+
|  alias/source-bucket-cmk |  b4edf839-7089-45b6-a18a-ec17a5cdb334  |
|  alias/sqs-queue-cmk     |  52086cfa-71dd-43e1-8cdc-0884d9628fed  |
|  alias/dest-bucket-cmk   |  b02b4d35-bbf3-4093-8c51-87e8e956a657  |
+--------------------------+----------------------------------------+
--- KMS key policy snippets (Principals only) ---
>>> alias/source-bucket-cmk
{
  "Sid": "EnableAccountRootAdmin",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:root"
  },
  "Action": "kms:*"
}
{
  "Sid": "AllowLambdaRoleDecryptForSourceReads",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:role/image-ingest-lambda-role"
  },
  "Action": [
    "kms:Decrypt",
    "kms:DescribeKey"
  ]
}
{
  "Sid": "AllowS3ServiceUseForBucketEncryption",
  "Principal": {
    "Service": "s3.amazonaws.com"
  },
  "Action": [
    "kms:Decrypt",
    "kms:GenerateDataKey"
  ]
}
>>> alias/sqs-queue-cmk
{
  "Sid": "EnableAccountRootAdmin",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:root"
  },
  "Action": "kms:*"
}
{
  "Sid": "AllowS3ToEncryptMessagesToQueue",
  "Principal": {
    "Service": "s3.amazonaws.com"
  },
  "Action": [
    "kms:GenerateDataKey",
    "kms:Decrypt"
  ]
}
{
  "Sid": "AllowLambdaRoleDecryptForReceive",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:role/image-ingest-lambda-role"
  },
  "Action": [
    "kms:Decrypt",
    "kms:DescribeKey"
  ]
}
>>> alias/dest-bucket-cmk
{
  "Sid": "EnableAccountRootAdmin",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:root"
  },
  "Action": "kms:*"
}
{
  "Sid": "AllowLambdaRoleEncryptForDestWrites",
  "Principal": {
    "AWS": "arn:aws:iam::000000000000:role/image-ingest-lambda-role"
  },
  "Action": [
    "kms:Encrypt",
    "kms:Decrypt",
    "kms:GenerateDataKey",
    "kms:DescribeKey"
  ]
}
{
  "Sid": "AllowS3ServiceUseForBucketEncryption",
  "Principal": {
    "Service": "s3.amazonaws.com"
  },
  "Action": [
    "kms:Decrypt",
    "kms:GenerateDataKey"
  ]
}

--- S3 buckets ---
[
    "ingest-dest-bucket",
    "ingest-source-bucket"
]
>>> source enc:
{
    "SSEAlgorithm": "aws:kms",
    "KMSMasterKeyID": "arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334"
}
>>> dest enc:
{
    "SSEAlgorithm": "aws:kms",
    "KMSMasterKeyID": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657"
}
>>> source notification:
{
    "QueueConfigurations": [
        {
            "Id": "ingest-source-to-queue",
            "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
            "Events": [
                "s3:ObjectCreated:*"
            ]
        }
    ]
}

--- SQS queues ---
>>> main:
{
  "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
  "KmsMasterKeyId": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed",
  "VisibilityTimeout": "180",
  "RedrivePolicy": {
    "deadLetterTargetArn": "arn:aws:sqs:us-east-1:000000000000:ingest-dlq",
    "maxReceiveCount": "5"
  },
  "Policy": {
    "Version": "2012-10-17",
    "Id": "ingest-events-queue-policy",
    "Statement": [
      {
        "Sid": "AllowS3SourceBucketSendMessage",
        "Effect": "Allow",
        "Principal": {
          "Service": "s3.amazonaws.com"
        },
        "Action": "sqs:SendMessage",
        "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
        "Condition": {
          "ArnEquals": {
            "aws:SourceArn": "arn:aws:s3:::ingest-source-bucket"
          }
        }
      }
    ]
  }
}
>>> dlq:
{
  "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-dlq",
  "KmsMasterKeyId": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed"
}

--- DDB ---
{
    "TableName": "image-ingest-records",
    "KeySchema": [
        {
            "AttributeName": "object_key",
            "KeyType": "HASH"
        }
    ],
    "AttrDefs": [
        {
            "AttributeName": "object_key",
            "AttributeType": "S"
        }
    ],
    "Status": "ACTIVE"
}

--- Lambda ---
{
    "FunctionName": "image-ingest-consumer",
    "Runtime": "python3.11",
    "Handler": "handler.lambda_handler",
    "Timeout": 30,
    "Role": "arn:aws:iam::000000000000:role/image-ingest-lambda-role",
    "Env": {
        "DEST_BUCKET": "ingest-dest-bucket",
        "TABLE_NAME": "image-ingest-records",
        "DEST_KMS_KEY_ID": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657"
    }
}

--- ESM ---
[
    {
        "State": "Enabled",
        "EventSourceArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
        "FunctionResponseTypes": [
            "ReportBatchItemFailures"
        ],
        "BatchSize": 10
    }
]

--- IAM role policy ---
[
    {
        "Sid": "Logs",
        "Action": [
            "logs:CreateLogGroup",
            "logs:CreateLogStream",
            "logs:PutLogEvents"
        ],
        "Resource": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/image-ingest-consumer*"
    },
    {
        "Sid": "ReadFromMainQueue",
        "Action": [
            "sqs:ReceiveMessage",
            "sqs:DeleteMessage",
            "sqs:GetQueueAttributes",
            "sqs:ChangeMessageVisibility"
        ],
        "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events"
    },
    {
        "Sid": "ReadSourceObjects",
        "Action": [
            "s3:GetObject"
        ],
        "Resource": "arn:aws:s3:::ingest-source-bucket/*"
    },
    {
        "Sid": "WriteDestObjects",
        "Action": [
            "s3:PutObject"
        ],
        "Resource": "arn:aws:s3:::ingest-dest-bucket/processed/*"
    },
    {
        "Sid": "WriteIngestRecord",
        "Action": [
            "dynamodb:PutItem"
        ],
        "Resource": "arn:aws:dynamodb:us-east-1:000000000000:table/image-ingest-records"
    },
    {
        "Sid": "DecryptSourceObjects",
        "Action": [
            "kms:Decrypt",
            "kms:DescribeKey"
        ],
        "Resource": "arn:aws:kms:us-east-1:000000000000:key/b4edf839-7089-45b6-a18a-ec17a5cdb334"
    },
    {
        "Sid": "DecryptQueueMessages",
        "Action": [
            "kms:Decrypt",
            "kms:DescribeKey"
        ],
        "Resource": "arn:aws:kms:us-east-1:000000000000:key/52086cfa-71dd-43e1-8cdc-0884d9628fed"
    },
    {
        "Sid": "EncryptDestObjects",
        "Action": [
            "kms:Encrypt",
            "kms:Decrypt",
            "kms:GenerateDataKey",
            "kms:DescribeKey"
        ],
        "Resource": "arn:aws:kms:us-east-1:000000000000:key/b02b4d35-bbf3-4093-8c51-87e8e956a657"
    }
]
  • Create 3 KMS keys + aliases with scoped policies
  • Create DDB table image-ingest-records
  • Create S3 buckets with SSE-KMS default encryption
  • Create DLQ and main SQS queue with SSE-KMS and redrive
  • Attach inline policies to lambda role
  • Set queue policy + S3 notification config
  • Zip handler and deploy lambda with env vars
  • Create ESM with ReportBatchItemFailures
  • Run end-to-end test + partial-batch test
Stack is up end-to-end. Summary: **Verified working** - PUT `"spaced dir/another file with spaces.png"` → processed copy at `processed/spaced dir/...` and matching DDB row in ~4s (deadline was 60s). URL-encoded keys from the S3 event are decoded with `urllib.parse.unquote_plus` in `handler.py:29`. - DLQ stayed empty. `s3:TestEvent` messages from S3's notification validation are ack'd silently (`handler.py:21-25`) so they don't retry into the DLQ. - Direct invoke with a good + bad record returned exactly `{"batchItemFailures":[{"itemIdentifier":"bad-msg-bbbb"}]}`. ESM has `FunctionResponseTypes: [ReportBatchItemFailures]`. **Knobs worth noting** - Lambda timeout 30s, SQS visibility 180s (6×) , messages can't get redriven mid-processing. - DLQ redrive maxReceiveCount = 5. - 3 CMKs, separate aliases. Each key policy grants only what's needed: root admin, the lambda role (scoped actions), and where relevant `s3.amazonaws.com` service (for bucket default encryption / S3→SQS message encryption). No wildcards on KMS resources anywhere , the lambda's inline policy references the three CMKs by ARN. - Lambda inline policy resources are all narrow ARNs: `sqs:...:ingest-events`, `s3:::ingest-source-bucket/*`, `s3:::ingest-dest-bucket/processed/*`, `dynamodb:...table/image-ingest-records`, and the three KMS key ARNs. - SQS queue policy on main queue scoped to `Principal: s3.amazonaws.com` with `aws:SourceArn = ingest-source-bucket`. **Layout on disk** (`/app`) - `handler/handler.py` , lambda code - `policies/*.json` , key policies, queue policy, lambda trust + inline policy (rendered into `.rendered.json` with ARNs substituted) - `build/handler.zip` , deployed artifact - `.vars` , resource ARNs/IDs for re-runs
Final diff , what the agent changed

No file changes, the agent left the workspace untouched.

Verifier output , the proof behind the reward
tests/test.sh
============================= test session starts ==============================
platform linux -- Python 3.12.3, pytest-8.4.1, pluggy-1.6.0 -- /root/.cache/uv/archive-v0/kzJ3NXRw8oUp52ep44Pgd/bin/python
cachedir: .pytest_cache
rootdir: /tests
plugins: json-ctrf-0.3.5
collecting ... collected 18 items

../tests/test_outputs.py::test_aws_cli_binary_is_real PASSED             [  5%]
../tests/test_outputs.py::test_localstack_reachable PASSED               [ 11%]
../tests/test_outputs.py::test_source_and_dest_buckets_use_customer_cmks PASSED [ 16%]
../tests/test_outputs.py::test_main_queue_and_dlq_exist_and_are_encrypted PASSED [ 22%]
../tests/test_outputs.py::test_lambda_exists_with_expected_handler PASSED [ 27%]
../tests/test_outputs.py::test_ddb_table_exists PASSED                   [ 33%]
../tests/test_outputs.py::test_source_bucket_notification_targets_main_queue PASSED [ 38%]
../tests/test_outputs.py::test_main_queue_policy_allows_s3_service PASSED [ 44%]
../tests/test_outputs.py::test_sqs_cmk_allows_s3_service PASSED          [ 50%]
../tests/test_outputs.py::test_source_cmk_allows_lambda_role_decrypt PASSED [ 55%]
../tests/test_outputs.py::test_dest_cmk_allows_lambda_role_encrypt PASSED [ 61%]
../tests/test_outputs.py::test_lambda_role_has_kms_decrypt_on_sqs_cmk PASSED [ 66%]
../tests/test_outputs.py::test_main_queue_visibility_timeout_covers_lambda_timeout PASSED [ 72%]
../tests/test_outputs.py::test_event_source_mapping_declares_report_batch_item_failures PASSED [ 77%]
../tests/test_outputs.py::test_lambda_handler_returns_correct_response_shape FAILED [ 83%]
../tests/test_outputs.py::test_end_to_end_preserves_object_size PASSED   [ 88%]
../tests/test_outputs.py::test_end_to_end_key_with_spaces_is_decoded PASSED [ 94%]
../tests/test_outputs.py::test_end_to_end_upload_propagates_to_dest_and_ddb PASSED [100%]

=================================== FAILURES ===================================
______________ test_lambda_handler_returns_correct_response_shape ______________

lmb = <botocore.client.Lambda object at 0xffffa8786c90>
sqs = <botocore.client.SQS object at 0xffffa8a2c500>
s3 = <botocore.client.S3 object at 0xffffa8d834a0>

    def test_lambda_handler_returns_correct_response_shape(lmb, sqs, s3):
        """Partial batch response shape."""
        probe_key = f"probe/verifier-{uuid.uuid4().hex[:8]}.bin"
        s3.put_object(Bucket=SRC_BUCKET, Key=probe_key, Body=b"x" * 32)
    
        main_arn = _queue_attrs(
            sqs, _queue_url(sqs, MAIN_QUEUE), attrs=("QueueArn",)
        )["QueueArn"]
    
        good_body = {
            "Records": [
                {
                    "s3": {
                        "bucket": {"name": SRC_BUCKET},
                        "object": {"key": probe_key},
                    }
                }
            ]
        }
        bad_body = {"some-other-shape": "not-an-s3-event"}
    
        good_mid = "msg-good-" + uuid.uuid4().hex[:8]
        bad_mid = "msg-bad-" + uuid.uuid4().hex[:8]
        event = {
            "Records": [
                {
                    "messageId": good_mid,
                    "body": json.dumps(good_body),
                    "eventSource": "aws:sqs",
                    "eventSourceARN": main_arn,
                    "awsRegion": REGION,
                },
                {
                    "messageId": bad_mid,
                    "body": json.dumps(bad_body),
                    "eventSource": "aws:sqs",
                    "eventSourceARN": main_arn,
                    "awsRegion": REGION,
                },
            ]
        }
    
        resp = lmb.invoke(
            FunctionName=LAMBDA_FUNC,
            InvocationType="RequestResponse",
            Payload=json.dumps(event).encode(),
        )
        func_err = resp.get("FunctionError")
        payload = resp["Payload"].read()
        assert not func_err, (
            f"Lambda invocation raised FunctionError={func_err}. "
            f"Payload: {payload!r}"
        )
        result = json.loads(payload) if payload else None
        assert isinstance(result, dict), (
            f"Lambda returned non-object payload: {result!r}. Expected "
            f"{{'batchItemFailures': [...]}}."
        )
        assert "batchItemFailures" in result, (
            f"Lambda response is missing the required `batchItemFailures` "
            f"key. AWS silently ignores any other key (e.g. "
            f"`failedBatchItems`) when FunctionResponseTypes includes "
            f"ReportBatchItemFailures. Got: {result}"
        )
        failures = result["batchItemFailures"]
        assert isinstance(failures, list), (
            f"batchItemFailures must be a list; got {type(failures).__name__}"
        )
        ids = [f.get("itemIdentifier") for f in failures]
>       assert bad_mid in ids, (
            f"Expected the bad record {bad_mid} in batchItemFailures; "
            f"got ids={ids}. The handler must catch per-record exceptions "
            f"and return the failed messageIds."
        )
E       AssertionError: Expected the bad record msg-bad-ba98c786 in batchItemFailures; got ids=[]. The handler must catch per-record exceptions and return the failed messageIds.
E       assert 'msg-bad-ba98c786' in []

/tests/test_outputs.py:522: AssertionError
=============================== warnings summary ===============================
test_outputs.py: 62 warnings
  /root/.cache/uv/archive-v0/kzJ3NXRw8oUp52ep44Pgd/lib/python3.12/site-packages/botocore/auth.py:424: DeprecationWarning: datetime.datetime.utcnow() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.datetime.now(datetime.UTC).
    datetime_now = datetime.datetime.utcnow()

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
==================================== PASSES ====================================
=========================== short test summary info ============================
PASSED ../tests/test_outputs.py::test_aws_cli_binary_is_real
PASSED ../tests/test_outputs.py::test_localstack_reachable
PASSED ../tests/test_outputs.py::test_source_and_dest_buckets_use_customer_cmks
PASSED ../tests/test_outputs.py::test_main_queue_and_dlq_exist_and_are_encrypted
PASSED ../tests/test_outputs.py::test_lambda_exists_with_expected_handler
PASSED ../tests/test_outputs.py::test_ddb_table_exists
PASSED ../tests/test_outputs.py::test_source_bucket_notification_targets_main_queue
PASSED ../tests/test_outputs.py::test_main_queue_policy_allows_s3_service
PASSED ../tests/test_outputs.py::test_sqs_cmk_allows_s3_service
PASSED ../tests/test_outputs.py::test_source_cmk_allows_lambda_role_decrypt
PASSED ../tests/test_outputs.py::test_dest_cmk_allows_lambda_role_encrypt
PASSED ../tests/test_outputs.py::test_lambda_role_has_kms_decrypt_on_sqs_cmk
PASSED ../tests/test_outputs.py::test_main_queue_visibility_timeout_covers_lambda_timeout
PASSED ../tests/test_outputs.py::test_event_source_mapping_declares_report_batch_item_failures
PASSED ../tests/test_outputs.py::test_end_to_end_preserves_object_size
PASSED ../tests/test_outputs.py::test_end_to_end_key_with_spaces_is_decoded
PASSED ../tests/test_outputs.py::test_end_to_end_upload_propagates_to_dest_and_ddb
FAILED ../tests/test_outputs.py::test_lambda_handler_returns_correct_response_shape
================== 1 failed, 17 passed, 62 warnings in 12.04s ==================

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_02ced5438e3b445b. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_02ced5438e3b445b · verifier authoritative; classifier explanatory.