Serverless Layers

• Automatically attaches layers to the provider and for each function
  • Skips functions with no other layers as they will use the layer(s) we added to the provider
• Creates a new layer's version when dependencies are updated
• Does not publish a new layer if dependencies are unchanged
• Drastically reduces lambda size
• Reduces deployment time
• Allows sharing of the same layers (libraries) among all lambda functions

Options

• NodeJS
• Ruby
• Python

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

Option	Type	Default	Description
compileDir	string	.serverless	Compilation directory
layersDeploymentBucket	string		Specify a bucket to upload lambda layers. Required if deploymentBucket is not defined.
customInstallationCommand	string		Specify a custom command to install dependencies, e.g., MY_ENV=1 npm --proxy http://myproxy.com i -P
customHash	string		Specify a custom string that, once changed, will force a new build of the layer
retainVersions	int	null	Number of layer versions to keep; older versions will be removed after deployments

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, use compatibleRuntimes
dependenciesPath	string	package.json	Note: >= 2.x versions. You can specify a custom path for your package.json
compatibleRuntimes	array	['nodejs']	Possible values: nodejs, nodejs10.x, nodejs12.x
layerOptimization.cleanupPatterns	array	check	Pattern of files to cleanup in the layer artifact before uploading it

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 a custom path for your Gemfile
compatibleRuntimes	array	['ruby']	Possible values: ruby2.5, ruby2.7
layerOptimization.cleanupPatterns	array	check	Pattern of files to cleanup in the layer artifact before uploading it

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 a custom path for your requirements.txt
compatibleRuntimes	array	['python']	Possible values: python2.7, python3.x
layerOptimization.cleanupPatterns	array	check	Pattern of files to cleanup in the layer artifact before uploading it

Default Serverless Setup

This plugin will set up the following options automatically if not specified in serverless.yml.

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

Minimal 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": "*"
      }
   ]
}

License

MIT

Contributors

Yes, thank you! This plugin is community-driven, and 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.

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