Localstack lambda throwing "handler not set" error

Question

I'm trying to upgrade localstack to the latest v3 version, however, I'm running into lambda invocation errors with any localstack image > 2.0.

time="2024-03-01T15:08:27Z" level=warning msg="Cannot list external agents" func=go.amzn.com/lambda/agents.ListExternalAgentPaths file="/home/runner/work/lambda-runtime-init/lambda-runtime-init/lambda/agents/agent.go:24" error="open /opt/extensions: no such file or directory"
teams-localstack                                                              | 2024-03-01T15:08:27.057  INFO --- [   asgi_gw_2] localstack.request.aws     : AWS dynamodb.ListTables => 200
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | Traceback (most recent call last):
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  |   File "/var/app/awslambdaric/__main__.py", line 15, in main
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  |     handler = args[1]
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  |               ~~~~^^^
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | IndexError: list index out of range
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | 
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | During handling of the above exception, another exception occurred:
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | 
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | Traceback (most recent call last):
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  |   File "<frozen runpy>", line 198, in _run_module_as_main
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  |   File "<frozen runpy>", line 88, in _run_code
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  |   File "/var/app/awslambdaric/__main__.py", line 25, in <module>
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  |     main(sys.argv)
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  |   File "/var/app/awslambdaric/__main__.py", line 17, in main
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  |     raise ValueError("Handler not set")
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | ValueError: Handler not set
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | time="2024-03-01T15:08:27Z" level=warning msg="First fatal error stored in appctx: Runtime.ExitError" func=go.amzn.com/lambda/appctx.StoreFirstFatalError file="/home/runner/work/lambda-runtime-init/lambda-runtime-init/lambda/appctx/appctxutil.go:157"
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | time="2024-03-01T15:08:27Z" level=warning msg="Process runtime-1 exited: exit status 1" func="go.amzn.com/lambda/rapid.(*rapidContext).setupEventsWatcher.func1" file="/home/runner/work/lambda-runtime-init/lambda-runtime-init/lambda/rapid/start.go:236"
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | time="2024-03-01T15:08:27Z" level=error msg="Init failed" func=go.amzn.com/lambda/rapid.handleInitError file="/home/runner/work/lambda-runtime-init/lambda-runtime-init/lambda/rapid/exit.go:109" InvokeID= error="Runtime exited with error: exit status 1"
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67  | time="2024-03-01T15:08:27Z" level=error msg="Runtime init failed to initialize: InitDoneFailed. Exiting." func=main.main file="/home/runner/work/lambda-runtime-init/lambda-runtime-init/cmd/localstack/main.go:238"
teams-localstack-lambda-teams-custom-events-7c7b33a738a1a44641260166299bda67 exited with code 0

1. I have 5 lambdas reusing the same image.
2. If I list the lambda functions I can see the handlers for all these.
3. This works correctly in localstack version 1.4

My docker compose file

version: "3"

services:
  teams-postgres:
    environment:
      POSTGRES_PASSWORD: sealion
      POSTGRES_USER: sealion
      POSTGRES_DB: teams
      POSTGRES_PORT: 5432
    ports:
      - "5432:5432"
    healthcheck:
      interval: 5s
      retries: 5
    image: postgres:13
    networks:
      - sealion-network

  teams-lambda:
    image: teams-lambda:latest
    build:
      dockerfile: Dockerfile.lambda
      context: .
    container_name: teams-lambda
    networks:
      - sealion-network
    privileged: true

  teams-localstack:
    container_name: teams-localstack
    environment:
      - services=s3,sns,sqs,lambda,stepfunctions,dynamodb
      # - HOSTNAME_EXTERNAL=teams-localstack
      - LAMBDA_REMOTE_DOCKER=true
      - LOCALSTACK_HOST=localstack
      - LAMBDA_REMOVE_CONTAINERS=false
      - PROVIDER_OVERRIDE_LAMBDA=v2
      # - LAMBDA_EXECUTOR=docker
      # - HOST_TMP_FOLDER=/tmp/localstack
      - DOCKER_HOST=unix:///var/run/docker.sock
      - AWS_DEFAULT_REGION=us-west-2
      - USE_LOCALSTACK=true
      # - DEBUG=true
      - LAMBDA_FORWARD_URL=http://teams-lambda:8080
    env_file:
      - .env
    healthcheck:
      interval: 5s
      start_period: 10s
      test: [ CMD, bash, -c, awslocal dynamodb list-tables ]
      timeout: 10s
    image: localstack/localstack-pro:3.0.0
    networks: [ sealion-network ]
    ports:
      - "127.0.0.1:53:53"
      - "127.0.0.1:5053:53/udp"
      - "127.0.0.1:443:443"
      - "127.0.0.1:4510-4530:4510-4530"
      - "127.0.0.1:4566:4566"
      - "127.0.0.1:4571:4571"
    volumes:
      - "${TMPDIR:-/tmp}/localstack:/var/lib/localstack"
      - "/var/run/docker.sock:/var/run/docker.sock"
      - ./localstack/init.py:/etc/localstack/init/ready.d/init.py # Ready hook
    privileged: true

volumes:
  postgres_data_container:
  dynamodata: {}

networks: { sealion-network: null }

Dockerfile

FROM xyz as deps
RUN apt install gcc g++ git

COPY . ${LAMBDA_TASK_ROOT}

ADD poetry.lock pyproject.toml poetry.toml ./
RUN poetry install --no-dev --no-interaction --no-ansi -vvv --no-root


FROM xyz:python-3.11

COPY --from=deps /var/app/.venv /var/app/.venv

COPY . .

What's going wrong here?

Answer 1

The issue was that I was using the --handler argument instead of --image-config to set the start-up command.