Serverless Layers

How to reduce drastically lambda size

serverless-layers

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  • It attaches automatically layers for each function
  • It creates a new layer's version when dependencies is updated
  • If dependencies is not changed, it does not publish a new layer
  • It reduces drastically lambda size
  • It reduces deployment time.
  • You can share same layers (libraries) among all lambda functions

Options

Common requirements

  • AWS only (sorry)
  • Serverless >= 1.34.0 (layers support)

Install

npm install -D serverless-layers

or

serverless plugin install --name serverless-layers

Add the plugin to your serverless.yml file:

Single layer config

Example:

plugins:
  - serverless-layers
  
custom:
  serverless-layers:
    functions: # optional
      - my_func2
    dependenciesPath: ./package.json

functions:
  my_func1:
    handler: handler.hello
  my_func2:
    handler: handler.hello

Multiple layers config

Example:

plugins:
  - serverless-layers
  
custom:
  serverless-layers:
    # applies for all lambdas 
    - common:
        dependenciesPath: ./my-folder/package.json
    # apply for foo only
    - foo:
        functions:
          - foo
        dependenciesPath: my-folder/package-foo.json
    - staticArn:
        functions:
          - foo
          - bar
        arn: arn:aws:lambda:us-east-1:<your_account>:layer:node-v13-11-0:5

functions:
  foo:
    handler: handler.hello
  bar:
    handler: handler.hello

Screen Shot 2020-04-05 at 2 04 38 pm

| Option | Type | Default | Description | | -------------- | --------- | ----------- | ----------- | | compileDir | string | .serverless | Compilation directory | | layersDeploymentBucket | string | | You can specify a bucket to upload lambda layers. Required if deploymentBucket is not defined. | | customInstallationCommand | string | | It specify a custom command to install deps ex. MY_ENV=1 npm --proxy http://myproxy.com i -P |

NodeJS

Requirements

  • Node >= v6.10.3
  • NPM >= 3.10.10
  • A valid package.json file

Options

| Option | Type | Default | Description | | -------------- | --------- | ----------- | ----------- | | packageManager | string | npm | Possible values: npm, yarn | | packagePath | string | package.json | (DEPRECATED): Available for <= 1.5.0, for versions >= 2.x please use compatibleRuntimes | | dependenciesPath | string | package.json | Note: >= 2.x versions. You can specify custom path for your package.json | | compatibleRuntimes | array | ['nodejs'] | Possible values: nodejs, nodejs10.x, nodejs12.x |


Ruby

Requirements

  • Ruby >= 2.5
  • A valid Gemfile file

Options

| Option | Type | Default | Description | | -------------- | --------- | ----------- | ----------- | | packageManager | string | bundle | Possible values: bundle | | dependenciesPath | string | Gemfile | Note: Available for >= 2.x versions. You can specify custom path for your requirements.txt | | compatibleRuntimes | array | ['ruby'] | Possible values: ruby2.5, ruby2.7 |


Python

Requirements

  • Python >= 2.7
  • A valid requirements.txt file

Options

| Option | Type | Default | Description | | -------------- | --------- | ----------- | ----------- | | packageManager | string | pip | Possible values: pip | | dependenciesPath | string | requirements.txt | Note: Available for >= 2.x versions. You can specify custom path for your requirements.txt | | compatibleRuntimes | array | ['python'] | Possible values: python2.7, python3.6, python3.7 and python3.8 |


Default Serverless Setup

This plugin will setup follow options automatically if not specified at serverless.yml.

| Option | Type | Default | | -------------- | --------- | ----------- | | package.individually | bool | false | | package.exclude | array | ['node_modules/**'] | | package.excludeDevDependencies | bool | false |

Mininal Policy permissions for CI/CD IAM users

serverless-layers-policy.json

{
   "Version":"2012-10-17",
   "Statement":[
      {
         "Effect":"Allow",
         "Action":[
            "s3:PutObject",
            "s3:GetObject"
         ],
         "Resource": "arn:aws:s3:::examplebucket"
      },
      {
         "Effect":"Allow",
         "Action":[
            "cloudformation:DescribeStacks"
         ],
         "Resource": "*"
      },
      {
         "Effect":"Allow",
         "Action":[
            "lambda:PublishLayerVersion"
         ],
         "Resource": "*"
      }
   ]
}

Contributing

Yes, thank you! This plugin is community-driven, most of its features are from different authors. Please update the docs and tests and add your name to the package.json file. We try to follow Airbnb's JavaScript Style Guide.

License

MIT