AWS Lambda - Upload `node_modules` without `devDependencies`.md

AWS Lambda - Upload node_modules without devDependencies

By default, ZIPing the project directory will included all of your devDependencies. slowing your upload speed to a crawl as you upload an enormous bundle containing 80% useless code (unless you're testing in production™ )

You only need your production dependencies when deploying, but need you devDependencies for development. But you have to deploy from the same directory, and it must be named node_modules. How can slim down the ol' deploy bundle?

Here's a horrible but effective hack that accomplishes this:

1. We'll create an additional directory called node_modules__prod for storing production dependencies.
2. When we deploy we swap the names of the dev and production node_modules directories 😱, so the deploy tool stupidly uploads what it thinks is our full node_modules but actually is our production-only modules directory.
3. When deploy is done (or fails) we swap the directory names again, restoring us back to development mode with full devDependencies again.

export $(egrep -v '^#' .env | xargs) # Read vars from .env
rm function.zip  # Clean up previous build

# Module folder name swap
mv node_modules node_modules__stash_while_building
mv node_modules__prod node_modules

zip -r function.zip \
  app.js \
  node_modules \ # Now using production-only deps
  package.json

echo "🌀 Uploading..."
aws lambda update-function-code \
  --function-name=$LAMBDA_FUNCTION_NAME \
  --profile=$AWS_CLI_UPLOAD_CODE_PROFILE \
  --region=$LAMBDA_REGION \
  --zip-file=fileb://function.zip && \
	echo "✅  Deploy complete"

# Unswap the directories again, and we're back to dev mode
mv node_modules node_modules__prod
mv node_modules__stash_while_building node_modules

This script assumes the AWS CLI is installed and a .env containing $LAMBDA_FUNCTION_NAME, $AWS_CLI_UPLOAD_CODE_PROFILE and $LAMBDA_REGION

Remember to add node_modules__prod and node_modules__stash_while_building to your .gitignore

Keeping both module directories in sync

Hey! But now these two directories can get out of sync!

Here's a script that will run any NPM command against both directories, keeping them in sync.

Here's how you use it:

./npmDuo.sh install lodash.get
./npmDuo.sh uninstall lodash.get

And here's the script itself. Add it to your project directory.

echo "npmDuo: Running command in dev node_modules..."
npm $1 $2

# Swap
mv node_modules node_modules__stash_while_installing
mv node_modules__prod node_modules

echo "npmDuo: Running command in production node_modules..."
npm $1 --production $2

# Unswap
mv node_modules node_modules__prod 
mv node_modules__stash_while_installing node_modules

echo "npmDuo Done"

Remember to give ./npmDuo.sh execute permissions with chmod +x ./npmDuo.sh