buildLayers.sh - Script to build NodeJS Lambda Layers for Serverless projects

buildLayers.sh

###
# Script to build the Lambda Layers based on libs used by functions.
# Assumptions... 
# - your functions are all inside ./functions
# - you don't need specific versions of the dependecies
###

#!/bin/bash

echo "======================================="
echo "Creating Lambda Layers..."

node_version=`cat .nvmrc | sed "s/v//"`
echo "Building layer: NodeJS:$node_version"

echo "Fetching required libraries:"
requires=`find ./functions/* | xargs grep "require(" | awk '{{
  str = $NF
  sub(/require\(./, "", str)
  sub(/\/[a-zA-Z0-9-]+.\);?/, "", str)
  sub(/.\)[;\.]?.+/, "", str)
  print str
}}' | sort | uniq`
echo "======================================="
echo "=> Used libraries: " $requires

BASE_DIR=`pwd`
ZIP_FILE=`grep "layers/nodejs" serverless.yml | awk '{{
  str = $NF
  sub(/^(layers\/)/, "", str)
  print str
}}'`
echo "======================================="
echo "Building ${BASE_DIR}/layers/${ZIP_FILE}"

declare -a libraries
for req in $requires
do
  echo "Searching for $req..."
  lib=`grep "$req" package.json | awk '{ print $1 }' | sed "s/[\":]//g"`
  echo "=> found $lib"
  if [[ -z "$lib" ]]; then
    echo "=> settled $req"
    libraries+=("$req")
  else
    echo "=> found $lib"
    libraries+=("$lib")
  fi
done
echo "======================================="
echo "Resolved libraries ${libraries[*]}"

cd layers 

echo "Fetching dependecies..."
mkdir _build
cp package.template.json _build/package.json
cd _build
yarn add ${libraries[*]}
echo "=> Dependecies fetched!"

# Remove unused stuff
echo "======================================="
rm package.json
rm yarn.lock

# Add files from staging area to zip
zip -q -r "${BASE_DIR}/layers/${ZIP_FILE}" .
echo "Zipped layer size: $(ls -s --block-size=1048576 ${BASE_DIR}/layers/${ZIP_FILE} | cut -d' ' -f1)M"
# Package layers folder into .zip
# Remove unused stuff
echo "======================================="

# Cleanup build dir
cd $CURRENT_DIR
rm -rf layers/_build &

echo "All done!"