docker custom runtime

bootstrap

#!/bin/sh

set -euo pipefail

# Initialization - load function handler
source $LAMBDA_TASK_ROOT/"$(echo $_HANDLER | cut -d. -f1).sh"

# Processing
while true
do
  HEADERS="$(mktemp)"
  # Get an event. The HTTP request will block until one is received
  EVENT_DATA=$(curl -sS -LD "$HEADERS" "http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/next")

  # Extract request ID by scraping response headers received above
  REQUEST_ID=$(grep -Fi Lambda-Runtime-Aws-Request-Id "$HEADERS" | tr -d '[:space:]' | cut -d: -f2)

  # Run the handler function from the script
  RESPONSE=$($(echo "$_HANDLER" | cut -d. -f2) "$EVENT_DATA")

  # Send the response
  curl --silent "http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/$REQUEST_ID/response"  -d "$RESPONSE"
done

Dockerfile

FROM public.ecr.aws/lambda/provided:latest

COPY bootstrap ${LAMBDA_RUNTIME_DIR}

COPY function.sh ${LAMBDA_TASK_ROOT}

RUN chmod a+x ${LAMBDA_RUNTIME_DIR}/bootstrap

CMD [ "function.handler" ]

function.sh

function handler () {
  EVENT_DATA=$1
  echo "$EVENT_DATA" 1>&2;
  RESPONSE="Echoing request: '$EVENT_DATA'"

  echo $RESPONSE
}