Serverless Layer Template

This repo is derived from AnomalyInnovations/serverless-nodejs-starter

It provides the set up to create an AWS lambda layer with serverless using babel 7

• jest, eslint and prettier configured

Layers can then be used in any of your other lambdas

• e.g. a layer could be common code you use in many lambdas

A template with support for these layers: https://github.com/robcronin/serverless-lambda-with-optional-layer-template

For an example repo of a lambda with a layer created with these templates see here

Requirements

• Install the Serverless Framework
• Configure your AWS CLI

Install

sls install --url https://github.com/robcronin/serverless-layer-template --name [NAME_OF_YOUR_LAYER]

or

git clone https://github.com/robcronin/serverless-layer-template

• cd [NAME_OF_YOUR_LAYER]
• yarn
• ./setUp.sh - answer the prompts

Modify

Edit the code in the src directory as required

By default it is a simple sum function

Deploy

• yarn deploy or ./deploy.sh
  • This will transpile your code with babel, create the serverless package and deploy it
  • The output will give you the arn you will need in your lambda functions

Usage

• In your actual lambda elsewhere add this arn to your function config:

functions:
  hello:
    handler: handler.hello
    events:
      - http:
          path: hello
          method: get
    layers:
      - [YOUR_ARN_HERE]

• At runtime the code in your layer will now be located at /opt
• If you had deployed the default sum function in this repo, you could then import it with:

import { sum } from '/opt/[LAYER_NAME]';

Local usage

• As you are not creating endpoints you can't use the useful sls invoke or sls offline start
• If you wish to use your layer locally in another lambda, one solution is to copy your code to your local /opt
  • ./local.sh will do this for you (requires sudo permission)
  • While developing the code in your layer you can use yarn watch which will run local.sh after any file changes (requires sudo permission)
• Note: if you use webpack in your main function you may run into issues with this, use https://github.com/robcronin/serverless-lambda-with-optional-layer-template for a working template

Tests

yarn test will run:

• yarn lint
• yarn jest