TL;DR - Summarizing serverless syntax which is often used, yet easily forgotten..

Time and time again when working in a project with the Serverless framework I find myself googling for the same things. I decided to once and for all list the syntactic sugar I so often use.

Cheat sheet

Create a new project starting out from a template:
serverless create --template aws-python3
Serverless framework template outline:
service: name: plugins: - serverless-iam-roles-per-function provider: name: aws runtime: python3.8 functions: MyFirstFunction: handler: handler.handle events: resources: - Resources: SomeBucket: Type: AWS::S3::Bucket Outputs: UsersTableArn:
Installing plugins
npm install --save some-plugin # In your serverless.yml file add the plugin plugins: - some-plugin
Define IAM roles per function:
# add plugin plugins: - serverless-iam-roles-per-function # add IAM role on function level fuctions: MyFirstFunction: ... iamRoleStatements: - Effect: "Allow" Action: - s3:PutObject Resource: 'your-bucket-arn'
Referencing variables from the same template:
provider: name: aws region: ${opt:region, 'eu-west-1'} # Overwrite the default region used. Default is us-east-1 deploymentBucket: name: my-own-bucket-in-${self:provider.region}
Giving a default variable for an option:
# In this case the default for stage is 'test' provider: name: aws runtime: python3.8 stage: ${opt:stage, 'test'}
Pseudo parameters references: pseudo parameters are parameters that are predefined by CloudFormation eg. AccountId or Region

    # Install plugin
    plugins:
      - serverless-pseudo-parameters
    # Use with #
    functions:
      MyFirstFunction:
        ..
        events:
          - s3:
              bucket: my-bucket-#{AWS::AccountId}
              event: s3:ObjectRemoved:*

Defining other resources in a separate file:
# In order to define resources in your serverless.yml AND other files use this syntax resources: - ${file(resources/dynamodb.yml)} - Resources: SomeBucket: Type: AWS::S3::Bucket
Using the intrinsic function Fn::Join to join multiple values into one string separated by a denominator
# For example to define the iamRoleStatement we mentioned abouve functions: MyFirstFunction: ... iamRoleStatements: - Effect: "Allow" Action: - s3:PutObject Resource: Fn::Join: - "" - - "arn:aws:s3:::" - Ref: "SomeBucket" - "/*"
Referring to another resource in the same stack
# For example as an environment variable functions: MyFirstFunction: ... environment: BUCKET_NAME: Ref: SomeBucket
Using the intrinsic function Fn::GetAtt: to get an attribute of a resource in the same stack
# either use this: BucketARN: 'Fn::GetAtt': [SomeBucket, Arn] # or this: BucketARN: { Fn::GetAtt: [ SomeBucket, Arn ] }
Package functions individually
service: ... package: individually: true functions: MyFirstFunction: handler: ... package: artifact: hello.jar
Resources:
Serverless framework reference: https://serverless.com/framework/docs/providers/aws/guide/serverless.yml/
https://theburningmonk.com/2019/05/cloudformation-protip-use-fnsub-instead-of-fnjoin/
Serverless environment variables: https://adamdelong.com/serverless-environment-variables/

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Serverless framework cheat sheet

Cheat sheet

Resources: