Lambda Container Images

Key	Value
Services	Lambda, ECR
Integrations	AWS CLI, Docker
Categories	Serverless; Containers

Introduction

A demo application illustrating Lambda container images with LocalStack. The Lambda image is built using Docker and pushed to a local ECR registry, then deployed and invoked as a container-based Lambda function.

Prerequisites

A valid LocalStack for AWS license. Your license provides a LOCALSTACK_AUTH_TOKEN to activate LocalStack.
Docker
localstack CLI
awslocal CLI

Check prerequisites

make check

Installation

make install

Start LocalStack

export LOCALSTACK_AUTH_TOKEN=<your-auth-token>
make start

Run the application

make run

The script:

Creates a local ECR repository.
Builds the Lambda Docker image and pushes it to the ECR registry.
Deploys the Lambda function using the container image.
Invokes the Lambda function and shows the response.

You should see output similar to:

Creating a new ECR repository locally
Building the Docker image, pushing it to ECR URL: localhost:4513/repo1
...
Deploying Lambda function from container image locally
{
    "FunctionName": "ls-lambda-image",
    ...
    "PackageType": "Image"
}
Invoking Lambda function from container image
{
    "StatusCode": 200,
    "LogResult": "",
    "ExecutedVersion": "$LATEST"
}
Done - test successfully finished.

The Lambda invocation logs are visible in the LocalStack container output (with DEBUG=1 enabled):

DEBUG:localstack_ext.services.awslambda.lambda_extended: Log output for invocation of Lambda "ls-lambda-image":
INIT: Using Lambda API Runtime target host: 'ls-lambda-image.us-east-1.localhost.localstack.cloud:4566'
INIT: Starting daemons...
INIT: Host 'ls-lambda-image.us-east-1.localhost.localstack.cloud' resolves to '172.17.0.2'
-----
Hello from LocalStack Lambda container image!

Troubleshooting

UnsupportedMediaTypeException

An error occurred (UnsupportedMediaTypeException) when calling the Invoke operation (reached max retries: 0): The payload is not JSON: b'\xb5\xeb-\xb5\xeb-'

Solution: Downgrade your awslocal CLI to version 1, or update the Lambda invocation to use --cli-binary-format raw-in-base64-out:

awslocal lambda invoke --cli-binary-format raw-in-base64-out \
    --function-name ls-lambda-image \
    --payload '{"test": "test"}' /tmp/lambda.out \
    --log-type Tail --query 'LogResult' --output text | base64 -d

License

This code is available under the Apache 2.0 license.