sam-build-yarn

Command to build AWS SAM apps that use nodejs with yarn.

Supports local file dependencies, and matches the sam build command output so you can use the sam-build-yarn command as a replacement for sam build.

NOTE: Currently does not support building using a container e.g. sam build --container

• Specify commands to run before building in a function by including a sam:prebuild script in the package.json.

AWS SAM Yarn Builder is a ruby gem, so you can install it using this command:

$ gem install aws-sam-yarn-builder

Execute:

$ sam-build-yarn

Assumes the template is located at the root of the project and named template.yml. You can specify a different template file like so:

$ sam-build-yarn --template-file ./samapp.yaml

For an example of how this builder can work, here is the layout of an example SAM app with a single function (under src) with a local nodejs dependency (under lib):

sam-app/
├── lib/
│   └── local-dependency/
│       ├── index.js
│       └── package.json
└── src/
    └── hello-world/
        ├── app.js
        └── package.json

The hello-world/package.json contents look like this:

{
  "name": "hello_world",
  "version": "1.0.0",
  "dependencies": {
    "local-file-dependency": "file:../../lib/local-file-dependency"
  }
}

With this layout and setup, you would not be able to build with sam build because it doesn't support dependencies that point to a file on the local filesystem.

sam-build-yarn will inspect all function package.json files for local file dependencies and "stage" them into the build before building each function, overriding the dependencies path in the package.json to point to the staged one.

The result of the build after running sam-build-yarn matches that of sam build:

sam-app/
├── .aws-sam/
│   └── build/
│       ├── HelloWorldFunction/
│       │   ├── node_modules/
│       │   ├── app.js
│       │   ├── package.json
│       │   └── yarn.lock
│       └── template.yaml
├── lib/
│   └── local-dependency/
│       ├── index.js
│       └── package.json
└── src/
    └── hello-world/
        ├── app.js
        └── package.json