Publing NPM modules as Lambda layers

I recently needed to use a Node-based Lambda where it depended on an NPM module.

https://github.com/mridang/serverless-servestatic-plugin/blob/a9e8f3c677e60be2065e84ded8cc5fe1da72e813/src/lambda.js#L7-L10

I didn't wan't to begin using a bundler, switch runtimes or do any workarounds. I just needed to get this custom resource up and running.

Note

I'm not sure whether this whole approach is overkill and could be better accomplished by using URL-based imports. At the time of writing, I haven't seen a URL-based imports except in Deno.

The following script installs the NPM packages into a directory called nodejs, packs it into an archive and then uploads it. The script is rather crude and publishes a new version of the layer on every invocation.

#!/bin/bash

# Variables
LAYER_NAME="adm-zip-layer"
RUNTIME="nodejs20.x"  # Change this to your Lambda's runtime
TEMP_DIR="adm-zip-layer"
ZIP_FILE="adm-zip-layer.zip"

# Step 1: Create directory structure
mkdir -p $TEMP_DIR/nodejs

# Step 2: Install adm-zip and dependencies into the nodejs folder
npm install adm-zip --prefix $TEMP_DIR/nodejs
npm install minimatch --prefix $TEMP_DIR/nodejs
npm install mime-types --prefix $TEMP_DIR/nodejs

# Step 3: Package the layer
cd $TEMP_DIR
zip -r ../$ZIP_FILE nodejs
cd ..

# Step 4: Publish the layer to AWS
aws lambda publish-layer-version --layer-name $LAYER_NAME \
  --zip-file fileb://$ZIP_FILE \
  --compatible-runtimes $RUNTIME

# Cleanup
rm -rf $TEMP_DIR
rm $ZIP_FILE

echo "Lambda layer $LAYER_NAME published successfully."

mridang/publish_npm_layer.md

mridang commented Oct 9, 2024