Lambda

Protocol: REST JSON Endpoint: http://localhost:4566/2015-03-31/functions/...

Lambda runs your function code inside real Docker containers — the same way real AWS Lambda does.

Supported Operations

Operation	Description
CreateFunction	Deploy a Lambda function
GetFunction	Get function details and download URL
GetFunctionConfiguration	Get runtime configuration
ListFunctions	List all functions
UpdateFunctionCode	Upload new code
DeleteFunction	Remove a function
Invoke	Invoke a function synchronously or asynchronously
CreateEventSourceMapping	Connect SQS / Kinesis / DynamoDB Streams to a function
GetEventSourceMapping	Get event source mapping details
ListEventSourceMappings	List all event source mappings
UpdateEventSourceMapping	Update a mapping
DeleteEventSourceMapping	Remove a mapping
PublishVersion	Publish an immutable version
CreateAlias	Create a named alias pointing to a version
GetAlias	Get alias details
ListAliases	List all aliases for a function
UpdateAlias	Update an alias
DeleteAlias	Delete an alias

Configuration

floci:
  services:
    lambda:
      enabled: true
      ephemeral: false                     # Remove container after each invocation
      default-memory-mb: 128
      default-timeout-seconds: 3
      docker-host: unix:///var/run/docker.sock
      runtime-api-base-port: 9200
      runtime-api-max-port: 9299
      code-path: ./data/lambda-code        # ZIP storage location
      poll-interval-ms: 1000
      container-idle-timeout-seconds: 300  # Idle container cleanup

Docker socket requirement

Lambda requires the Docker socket. Mount it in your compose file:

services:
  floci:
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock

Examples

export AWS_ENDPOINT=http://localhost:4566

# Package a simple Node.js function
cat > index.mjs << 'EOF'
export const handler = async (event) => {
  console.log("Event:", JSON.stringify(event));
  return { statusCode: 200, body: JSON.stringify({ hello: "world" }) };
};
EOF
zip function.zip index.mjs

# Deploy the function
aws lambda create-function \
  --function-name my-function \
  --runtime nodejs22.x \
  --role arn:aws:iam::000000000000:role/lambda-role \
  --handler index.handler \
  --zip-file fileb://function.zip \
  --endpoint-url $AWS_ENDPOINT

# Invoke synchronously
aws lambda invoke \
  --function-name my-function \
  --payload '{"key":"value"}' \
  --cli-binary-format raw-in-base64-out \
  response.json \
  --endpoint-url $AWS_ENDPOINT

cat response.json

# Invoke asynchronously
aws lambda invoke \
  --function-name my-function \
  --invocation-type Event \
  --payload '{"key":"value"}' \
  --cli-binary-format raw-in-base64-out \
  /dev/null \
  --endpoint-url $AWS_ENDPOINT

# Update code
zip function.zip index.mjs
aws lambda update-function-code \
  --function-name my-function \
  --zip-file fileb://function.zip \
  --endpoint-url $AWS_ENDPOINT

Event Source Mappings

Connect Lambda to SQS, Kinesis, or DynamoDB Streams:

# SQS trigger
QUEUE_ARN=$(aws sqs get-queue-attributes \
  --queue-url $AWS_ENDPOINT/000000000000/orders \
  --attribute-names QueueArn \
  --query Attributes.QueueArn --output text \
  --endpoint-url $AWS_ENDPOINT)

aws lambda create-event-source-mapping \
  --function-name my-function \
  --event-source-arn $QUEUE_ARN \
  --batch-size 10 \
  --endpoint-url $AWS_ENDPOINT

Supported Runtimes

Any runtime that has an official AWS Lambda container image works with Floci (e.g. nodejs22.x, python3.13, java21, go1.x, provided.al2023).