serverless-layers

• It attaches automatically layers to the provider and for each function
  • it will skip functions with no other layers as they will use the layer(s) we added to the provider
• 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

• 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		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
customHash	string		Can specify custom string, that once changed will force a new build of the layer
retainVersions	int	null	Number of layer versions to keep, the rest 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 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": "*"
      }
   ]
}

License

MIT

Contributors

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.

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