SyncVals · Trajectory

s3-lambda-ddb-pipeline

claude-code claude-opus-4-7 ✗ failed HARNESS_ERROR ↑ 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

HARNESS_ERRORInfrastructure failure, the agent never ran properly. Not a signal about agent or task.

SubtypeClassification Failed

EvidenceClaude Code classification failed: (classifier unavailable for this trial)

Root causeCould not analyze trial with Claude Code

RecommendationReview trial manually or check authentication

Trajectory

Tool-by-tool agent trajectory

9 tool calls · 2 tool types · 12 steps

# S3 -> Lambda -> DynamoDB event pipeline ## Environment - **AWS endpoint:** LocalStack at `http://localstack:4566`. All AWS SDKs and CLIs in this environment already honour the pre-exported `AWS_ENDPOINT_URL=http://localstack:4566`. - **Credentials & region:** `AWS_ACCESS_KEY_ID=test`, `AWS_SECRET_ACCESS_KEY=test`, `AWS_DEFAULT_REGION=us-east-1`. Account ID is `000000000000` (LocalStack's default), which is the value to use when constructing ARNs. - **Installed tools:** `aws` (AWS CLI v2), `awslocal` (pre-configured for LocalStack), `python3`, `boto3`, `curl`, `jq`, `git`, `unzip`, `zip`. A Python venv at `/opt/venv` with `boto3` and `awscli-local` is already on `PATH`. - **Lambda networking:** Lambda functions created in this environment run in Docker containers on the same Compose network as LocalStack and can reach it at `http://localstack:4566`. The function's own `AWS_ENDPOINT_URL` must be set to that value for SDK calls from inside the function to hit LocalStack rather than real AWS. - **Working directory:** `/app`. It is empty , there are no starter files, templates, handlers, hints, or secrets. Everything the pipeline needs must be authored by you. ## Task Build the pipeline described below from scratch and deploy it via **CloudFormation** , the grader rejects solutions built imperatively with the CLI or SDK. The end state must be produced by at least one CloudFormation stack named **`pipeline-stack`** that owns the S3 bucket, the DynamoDB table, and the Lambda function. You are free to split into multiple stacks, add custom resources, choose any logical IDs, and use either `Code.ZipFile` or `Code.S3Bucket` for the Lambda code. ## Required outcome After you finish, the following must all be true in the LocalStack account: 1. A CloudFormation stack named **`pipeline-stack`** exists in `CREATE_COMPLETE` or `UPDATE_COMPLETE` and its stack resources include the S3 bucket `pipeline-source`, the DynamoDB table `pipeline-events`, and the Lambda function `pipeline-processor`. 2. An S3 bucket named **`pipeline-source`** exists. 3. A DynamoDB table named **`pipeline-events`** exists with a single string partition key `object_key`. 4. A Lambda function named **`pipeline-processor`** exists (runtime `python3.11`) and is invoked whenever an object is created in `pipeline-source`. 5. When a new object is put into `pipeline-source`, the Lambda must write one item to `pipeline-events` with these attributes: - `object_key` (S) , the S3 object key - `bucket` (S) , the source bucket name - `size` (N) , the object size in bytes - `event_time` (S) , the S3 event timestamp (non-empty) 6. The Lambda must have permission to be invoked by the S3 service (`Principal: s3.amazonaws.com`) for events from `pipeline-source`. 7. The Lambda execution role must have `dynamodb:PutItem` permission on the `pipeline-events` table. 8. The `pipeline-events` table must be encrypted at rest with a **customer-managed** KMS CMK that is itself created by the `pipeline-stack` CloudFormation stack (not the AWS-managed `alias/aws/dynamodb` key). 9. The Lambda execution role must be able to use that CMK , its policy set must grant `kms:Decrypt` and `kms:GenerateDataKey` on the CMK's ARN (or with `Resource: "*"`). Without these, the Lambda's `PutItem` would fail against an encrypted table even though `dynamodb:PutItem` is granted. ## End-to-end grading The grader uploads a fresh object to `pipeline-source` with a key it chooses, then polls `pipeline-events` for an item whose `object_key` equals that same key. If the item does not appear within a reasonable timeout, the task fails. The grader does not trust any agent-written tests; all assertions run out-of-band against the live LocalStack account.

Check working directory and tools

shell

ls -la /app && which aws awslocal python3 && aws --version

output

total 8
drwxr-xr-x 2 root root 4096 Apr 21 17:23 .
drwxr-xr-x 1 root root 4096 Apr 23 05:30 ..
/usr/local/bin/aws
/opt/venv/bin/awslocal
/opt/venv/bin/python3
aws-cli/2.34.33 Python/3.14.4 Linux/6.10.14-linuxkit exe/aarch64.ubuntu.24

[stdout]
total 8
drwxr-xr-x 2 root root 4096 Apr 21 17:23 .
drwxr-xr-x 1 root root 4096 Apr 23 05:30 ..
/usr/local/bin/aws
/opt/venv/bin/awslocal
/opt/venv/bin/python3
aws-cli/2.34.33 Python/3.14.4 Linux/6.10.14-linuxkit exe/aarch64.ubuntu.24

Check LocalStack connectivity and existing stacks

shell

awslocal sts get-caller-identity && awslocal s3 ls && awslocal cloudformation list-stacks --query 'StackSummaries[*].[StackName,StackStatus]'

output

{
    "UserId": "AKIAIOSFODNN7EXAMPLE",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:root"
}
[]

[stdout]
{
    "UserId": "AKIAIOSFODNN7EXAMPLE",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:root"
}
[]

Check LocalStack service health

shell

curl -s http://localstack:4566/_localstack/health | head -c 1000

output

{"services": {"acm": "disabled", "apigateway": "disabled", "cloudformation": "running", "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": "disabled", "route53": "disabled", "route53resolver": "disabled", "s3": "running", "s3control": "disabled", "scheduler": "disabled", "secretsmanager": "disabled", "ses": "disabled", "sns": "disabled", "sqs": "disabled", "ssm": "disabled", "stepfunctions": "disabled", "sts": "running", "support": "disabled", "swf": "disabled", "transcribe": "disabled"}, "edition": "community", "version": "4.13.1"}

[stdout]
{"services": {"acm": "disabled", "apigateway": "disabled", "cloudformation": "running", "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": "disabled", "route53": "disabled", "route53resolver": "disabled", "s3": "running", "s3control": "disabled", "scheduler": "disabled", "secretsmanager": "disabled", "ses": "disabled", "sns": "disabled", "sqs": "disabled", "ssm": "disabled", "stepfunctions": "disabled", "sts": "running", "support": "disabled", "swf": "disabled", "transcribe": "disabled"}, "edition": "community", "version": "4.13.1"}

write · /app/handler.py

import os
import boto3

TABLE_NAME = os.environ["TABLE_NAME"]
ENDPOINT = os.environ.get("AWS_ENDPOINT_URL")

_client = boto3.client("dynamodb", endpoint_url=ENDPOINT) if ENDPOINT else boto3.client("dynamodb")


def handler(event, context):
    for record in event.get("Records", []):
        s3 = record["s3"]
        bucket = s3["bucket"]["name"]
        key = s3["object"]["key"]
        size = int(s3["object"].get("size", 0))
        event_time = record.get("eventTime", "")
        _client.put_item(
            TableName=TABLE_NAME,
            Item={
                "object_key": {"S": key},
                "bucket": {"S": bucket},
                "size": {"N": str(size)},
                "event_time": {"S": event_time},
            },
        )
    return {"ok": True}

write · /app/template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Description: S3 -> Lambda -> DynamoDB pipeline

Resources:

  PipelineKey:
    Type: AWS::KMS::Key
    Properties:
      Description: CMK for pipeline-events table
      EnableKeyRotation: false
      KeyPolicy:
        Version: '2012-10-17'
        Statement:
          - Sid: EnableRoot
            Effect: Allow
            Principal:
              AWS: !Sub arn:aws:iam::${AWS::AccountId}:root
            Action: kms:*
            Resource: '*'
          - Sid: AllowDynamoDB
            Effect: Allow
            Principal:
              Service: dynamodb.amazonaws.com
            Action:
              - kms:Encrypt
              - kms:Decrypt
              - kms:ReEncrypt*
              - kms:GenerateDataKey*
              - kms:DescribeKey
              - kms:CreateGrant
            Resource: '*'
          - Sid: AllowLambdaRoleUse
            Effect: Allow
            Principal:
              AWS: !Sub arn:aws:iam::${AWS::AccountId}:role/pipeline-processor-role
            Action:
              - kms:Decrypt
              - kms:GenerateDataKey
              - kms:DescribeKey
            Resource: '*'

  EventsTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: pipeline-events
      BillingMode: PAY_PER_REQUEST
      AttributeDefinitions:
        - AttributeName: object_key
          AttributeType: S
      KeySchema:
        - AttributeName: object_key
          KeyType: HASH
      SSESpecification:
        SSEEnabled: true
        SSEType: KMS
        KMSMasterKeyId: !GetAtt PipelineKey.Arn

  ProcessorRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: pipeline-processor-role
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
      Policies:
        - PolicyName: dynamodb-put
          PolicyDocument:
            Version: '2012-10-17'
            Statement:
              - Effect: Allow
                Action:
                  - dynamodb:PutItem
                Resource: !GetAtt EventsTable.Arn
        - PolicyName: kms-use
          PolicyDocument:
            Version: '2012-10-17'
            Statement:
              - Effect: Allow
                Action:
                  - kms:Decrypt
                  - kms:GenerateDataKey
                  - kms:DescribeKey
                Resource: !GetAtt PipelineKey.Arn

  ProcessorFunction:
    Type: AWS::Lambda::Function
    Properties:
      FunctionName: pipeline-processor
      Runtime: python3.11
      Handler: index.handler
      Role: !GetAtt ProcessorRole.Arn
      Timeout: 30
      Environment:
        Variables:
          TABLE_NAME: !Ref EventsTable
          AWS_ENDPOINT_URL: http://localstack:4566
      Code:
        ZipFile: |
          import os
          import boto3

          TABLE_NAME = os.environ["TABLE_NAME"]
          ENDPOINT = os.environ.get("AWS_ENDPOINT_URL")

          _client = boto3.client("dynamodb", endpoint_url=ENDPOINT) if ENDPOINT else boto3.client("dynamodb")


          def handler(event, context):
              for record in event.get("Records", []):
                  s3 = record["s3"]
                  bucket = s3["bucket"]["name"]
                  key = s3["object"]["key"]
                  size = int(s3["object"].get("size", 0))
                  event_time = record.get("eventTime", "")
                  _client.put_item(
                      TableName=TABLE_NAME,
                      Item={
                          "object_key": {"S": key},
                          "bucket": {"S": bucket},
                          "size": {"N": str(size)},
                          "event_time": {"S": event_time},
                      },
                  )
              return {"ok": True}

  InvokePermission:
    Type: AWS::Lambda::Permission
    Properties:
      FunctionName: !Ref ProcessorFunction
      Action: lambda:InvokeFunction
      Principal: s3.amazonaws.com
      SourceAccount: !Ref AWS::AccountId
      SourceArn: !Sub arn:aws:s3:::pipeline-source

  SourceBucket:
    Type: AWS::S3::Bucket
    DependsOn: InvokePermission
    Properties:
      BucketName: pipeline-source
      NotificationConfiguration:
        LambdaConfigurations:
          - Event: s3:ObjectCreated:*
            Function: !GetAtt ProcessorFunction.Arn

Outputs:
  BucketName:
    Value: !Ref SourceBucket
  TableName:
    Value: !Ref EventsTable
  FunctionName:
    Value: !Ref ProcessorFunction
  KeyArn:
    Value: !GetAtt PipelineKey.Arn

Create CloudFormation stack

shell

awslocal cloudformation create-stack --stack-name pipeline-stack --template-body file://template.yaml --capabilities CAPABILITY_NAMED_IAM

output

{
    "StackId": "arn:aws:cloudformation:us-east-1:000000000000:stack/pipeline-stack/27690efd-8bb5-4b71-a954-6c9e085dbc06"
}

[stdout]
{
    "StackId": "arn:aws:cloudformation:us-east-1:000000000000:stack/pipeline-stack/27690efd-8bb5-4b71-a954-6c9e085dbc06"
}

Wait for stack create

shell

awslocal cloudformation wait stack-create-complete --stack-name pipeline-stack && awslocal cloudformation describe-stacks --stack-name pipeline-stack --query 'Stacks[0].[StackStatus]' --output text

output

CREATE_COMPLETE

[stdout]
CREATE_COMPLETE

List stack resources

shell

awslocal cloudformation describe-stack-resources --stack-name pipeline-stack --query 'StackResources[*].[LogicalResourceId,ResourceType,ResourceStatus,PhysicalResourceId]' --output table

output

-----------------------------------------------------------------------------------------------------------------
|                                            DescribeStackResources                                             |
+-------------------+--------------------------+------------------+---------------------------------------------+
|  PipelineKey      |  AWS::KMS::Key           |  CREATE_COMPLETE |  cec4384e-bbd9-4d92-ae1b-158d0e51ac58       |
|  EventsTable      |  AWS::DynamoDB::Table    |  CREATE_COMPLETE |  pipeline-events                            |
|  ProcessorRole    |  AWS::IAM::Role          |  CREATE_COMPLETE |  pipeline-processor-role                    |
|  ProcessorFunction|  AWS::Lambda::Function   |  CREATE_COMPLETE |  pipeline-processor                         |
|  InvokePermission |  AWS::Lambda::Permission |  CREATE_COMPLETE |  pipeline-stack-InvokePermission-da77f136   |
|  SourceBucket     |  AWS::S3::Bucket         |  CREATE_COMPLETE |  pipeline-source                            |
+-------------------+--------------------------+------------------+---------------------------------------------+

[stdout]
-----------------------------------------------------------------------------------------------------------------
|                                            DescribeStackResources                                             |
+-------------------+--------------------------+------------------+---------------------------------------------+
|  PipelineKey      |  AWS::KMS::Key           |  CREATE_COMPLETE |  cec4384e-bbd9-4d92-ae1b-158d0e51ac58       |
|  EventsTable      |  AWS::DynamoDB::Table    |  CREATE_COMPLETE |  pipeline-events                            |
|  ProcessorRole    |  AWS::IAM::Role          |  CREATE_COMPLETE |  pipeline-processor-role                    |
|  ProcessorFunction|  AWS::Lambda::Function   |  CREATE_COMPLETE |  pipeline-processor                         |
|  InvokePermission |  AWS::Lambda::Permission |  CREATE_COMPLETE |  pipeline-stack-InvokePermission-da77f136   |
|  SourceBucket     |  AWS::S3::Bucket         |  CREATE_COMPLETE |  pipeline-source                            |
+-------------------+--------------------------+------------------+---------------------------------------------+

All resources created. Now let me end-to-end test by uploading an object and checking the table.

Upload test object and check DynamoDB

shell

echo "hello pipeline" > /tmp/test.txt && awslocal s3 cp /tmp/test.txt s3://pipeline-source/test-key-001.txt && sleep 5 && awslocal dynamodb get-item --table-name pipeline-events --key '{"object_key":{"S":"test-key-001.txt"}}'

output

Completed 15 Bytes/15 Bytes (861 Bytes/s) with 1 file(s) remaining
upload: ../tmp/test.txt to s3://pipeline-source/test-key-001.txt  
{
    "Item": {
        "bucket": {
            "S": "pipeline-source"
        },
        "object_key": {
            "S": "test-key-001.txt"
        },
        "size": {
            "N": "15"
        },
        "event_time": {
            "S": "2026-04-23T05:33:50.635Z"
        }
    }
}

[stdout]
Completed 15 Bytes/15 Bytes (861 Bytes/s) with 1 file(s) remaining
upload: ../tmp/test.txt to s3://pipeline-source/test-key-001.txt  
{
    "Item": {
        "bucket": {
            "S": "pipeline-source"
        },
        "object_key": {
            "S": "test-key-001.txt"
        },
        "size": {
            "N": "15"
        },
        "event_time": {
            "S": "2026-04-23T05:33:50.635Z"
        }
    }
}

Pipeline works end-to-end. The grader's expected item appeared in `pipeline-events` with all four required attributes after a fresh S3 PUT. **Stack status:** `pipeline-stack` is `CREATE_COMPLETE` with all six resources: - `PipelineKey` (KMS CMK) , encrypts the table; key policy allows DynamoDB to use it. - `EventsTable` (`pipeline-events`) , `object_key` (S) HASH, SSE via the CMK. - `ProcessorRole` , has `dynamodb:PutItem` on the table ARN and `kms:Decrypt` / `kms:GenerateDataKey` / `kms:DescribeKey` on the CMK ARN. - `ProcessorFunction` (`pipeline-processor`, `python3.11`) , inline `ZipFile` handler, `AWS_ENDPOINT_URL=http://localstack:4566` so SDK calls hit LocalStack. - `InvokePermission` , `lambda:InvokeFunction` for `s3.amazonaws.com` scoped to `arn:aws:s3:::pipeline-source`. - `SourceBucket` (`pipeline-source`) , `s3:ObjectCreated:*` notification to the Lambda; `DependsOn: InvokePermission` so the bucket creation doesn't race the permission.

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/Mi4dmZOfYQRWbRF4oSBXL/bin/python
cachedir: .pytest_cache
rootdir: /tests
plugins: json-ctrf-0.3.5
collecting ... collected 13 items

../tests/test_outputs.py::test_aws_cli_binary_is_real PASSED             [  7%]
../tests/test_outputs.py::test_localstack_reachable PASSED               [ 15%]
../tests/test_outputs.py::test_cfn_stack_is_deployed PASSED              [ 23%]
../tests/test_outputs.py::test_cfn_stack_owns_core_resources PASSED      [ 30%]
../tests/test_outputs.py::test_bucket_exists PASSED                      [ 38%]
../tests/test_outputs.py::test_table_exists_with_correct_schema PASSED   [ 46%]
../tests/test_outputs.py::test_lambda_exists_with_correct_runtime PASSED [ 53%]
../tests/test_outputs.py::test_lambda_permission_allows_s3_invoke PASSED [ 61%]
../tests/test_outputs.py::test_bucket_notification_points_at_lambda PASSED [ 69%]
../tests/test_outputs.py::test_stack_owns_customer_managed_kms_key PASSED [ 76%]
../tests/test_outputs.py::test_ddb_encrypted_with_stack_cmk PASSED       [ 84%]
../tests/test_outputs.py::test_lambda_role_can_use_the_cmk PASSED        [ 92%]
../tests/test_outputs.py::test_end_to_end_put_creates_ddb_item FAILED    [100%]

=================================== FAILURES ===================================
_____________________ test_end_to_end_put_creates_ddb_item _____________________

s3 = <botocore.client.S3 object at 0xffffab643020>
ddb = <botocore.client.DynamoDB object at 0xffffab14f080>

    def test_end_to_end_put_creates_ddb_item(s3, ddb):
        key = f"verifier/red flower-{uuid.uuid4().hex}.bin"
        body = struct.pack(">Q", int(time.time_ns())) + os.urandom(32)
        s3.put_object(Bucket=BUCKET, Key=key, Body=body)
    
        deadline = time.time() + 60
        last_err = None
        item = None
        while time.time() < deadline:
            try:
                resp = ddb.get_item(
                    TableName=TABLE,
                    Key={"object_key": {"S": key}},
                    ConsistentRead=True,
                )
                if "Item" in resp:
                    item = resp["Item"]
                    break
            except ClientError as e:
                last_err = e
            time.sleep(1)
    
>       assert item is not None, (
            f"Lambda never wrote item for key={key} within 60s; last_err={last_err}"
        )
E       AssertionError: Lambda never wrote item for key=verifier/red flower-c85e1e8effec40e0b8b1d2f1b2090330.bin within 60s; last_err=None
E       assert None is not None

/tests/test_outputs.py:297: AssertionError
=============================== warnings summary ===============================
test_outputs.py: 78 warnings
  /root/.cache/uv/archive-v0/Mi4dmZOfYQRWbRF4oSBXL/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_cfn_stack_is_deployed
PASSED ../tests/test_outputs.py::test_cfn_stack_owns_core_resources
PASSED ../tests/test_outputs.py::test_bucket_exists
PASSED ../tests/test_outputs.py::test_table_exists_with_correct_schema
PASSED ../tests/test_outputs.py::test_lambda_exists_with_correct_runtime
PASSED ../tests/test_outputs.py::test_lambda_permission_allows_s3_invoke
PASSED ../tests/test_outputs.py::test_bucket_notification_points_at_lambda
PASSED ../tests/test_outputs.py::test_stack_owns_customer_managed_kms_key
PASSED ../tests/test_outputs.py::test_ddb_encrypted_with_stack_cmk
PASSED ../tests/test_outputs.py::test_lambda_role_can_use_the_cmk
FAILED ../tests/test_outputs.py::test_end_to_end_put_creates_ddb_item - Asser...
============= 1 failed, 12 passed, 78 warnings in 60.52s (0:01:00) =============

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_b99ac293abbd4798. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_b99ac293abbd4798 · verifier authoritative; classifier explanatory.