Serverless Webpack

A Serverless v1.x plugin to build your lambda functions with Webpack.

This plugin is for you if you want to use the latest Javascript version with Babel; use custom resource loaders; try your lambda functions locally and much more!

BREAKING CHANGE IN v2: webpack must now be installed alongside serverless-webpack as a peer dependency. This allows more control over which version of Webpack to run.

Install

$ npm install serverless-webpack --save-dev

Add the plugin to your serverless.yml file:

plugins:
  - serverless-webpack

Configure

By default the plugin will look for a webpack.config.js in the service directory. Alternatively, you can specify a different file or configuration in serverless.yml:

custom:
  webpack: ./folder/my-webpack.config.js

An base Webpack configuration might look like this:

// webpack.config.js

module.exports = {
  entry: './handler.js',
  target: 'node',
  module: {
    loaders: [ ... ]
  }
};

Note that, if the output configuration is not set, it will automatically be generated to write bundles in the .webpack directory. If you set your own output configuration make sure to add a libraryTarget for best compatibility with external dependencies:

// webpack.config.js

module.exports = {
  // ...
  output: {
    libraryTarget: 'commonjs',
    path: '.webpack',
    filename: 'handler.js', // this should match the first part of function handler in `serverless.yml`
  },
  // ...
};

By default, the plugin will try to bundle all dependencies. However, you don't want to include all modules in some cases such as selectively import, excluding builtin package (ie: aws-sdk) and handling webpack-incompatible modules.

In this case you might add external modules in Webpack's externals configuration. Those modules can be included in the Serverless bundle with the webpackIncludeModules option in serverless.yml:

// webpack.config.js
var nodeExternals = require('webpack-node-externals')

modules.export = {
  // we use webpack-node-externals to excludes all node deps.
  // You can manually set the externals too.
  externals: [nodeExternals()],
}

# serverless.yml
custom:
  webpackIncludeModules: true # enable auto-packing of external modules

All modules stated in externals will be excluded from bundled files. If an excluded module is stated as dependencies in package.json, it will be packed into the Serverless artifact under the node_modules directory.

By default, the plugin will use the package.json file in working directory, If you want to use a different package file, set packagePath to your custom package.json:

# serverless.yml
custom:
  webpackIncludeModules:
    packagePath: '../package.json' # relative path to custom package.json file.

Note that only relative path is supported at the moment.

You can find an example setups in the examples folder.

Usage

Automatic bundling

The normal Serverless deploy procedure will automatically bundle with Webpack:

• Create the Serverless project with serverless create -t aws-nodejs
• Install Serverless Webpack as above
• Deploy with serverless deploy

Simulate API Gateway locally

To start a local server that will act like the API Gateway use the following command. Your code will be reloaded upon change so that every request to your local server will serve the latest code.

$ serverless webpack serve

Options are:

• --port or -p (optional) The local server port. Defaults to 8000

The serve command will automatically look for the local serverless.yml and serve all the http events. For example this configuration will generate a GET endpoint:

functions:
  hello:
    handler: handler.hello
    events:
      - http:
          method: get
          path: hello

Run a function locally

To run your bundled functions locally you can:

$ serverless webpack invoke --function <function-name>

Options are:

• --function or -f (required) is the name of the function to run
• --path or -p (optional) is a JSON file path used as the function input event

Run a function locally on source changes

Or to run a function every time the source files change use watch:

$ serverless webpack watch --function <function-name> --path event.json

Options are:

• --function or -f (required) is the name of the function to run
• --path or -p (optional) is a JSON file path used as the function input event

Using with serverless-offline and serverless-webpack plugin

Run serverless offline start. In comparison with serverless offline, the start command will fire an init and a end lifecycle hook which is needed for serverless-offline and serverless-dynamodb-local to switch off both resources.

Add plugins to your serverless.yml file:

plugins:
  - serverless-webpack
  - serverless-dynamodb-local
  - serverless-offline #serverless-offline needs to be last in the list

Bundle with webpack

To just bundle and see the output result use:

$ serverless webpack --out dist

Options are:

• --out or -o (optional) The output directory. Defaults to .webpack.

Example with Babel

In the examples folder there is a Serverless project using this plugin with Babel. To try it, from inside the example folder:

• npm install to install dependencies
• serverless webpack run -f hello to run the example function