Example of a Serverless system with Step Functions invoked by SNS

serverless.yml

service: state-machine-invoking-example

provider:
  name: aws
  region: eu-west-1
  runtime: python3.6
  # Specific Role for the Lambda and machine is better
  iamRoleStatements:
    - Effect: "Allow"
      Action:
        - "states:StartExecution"
      Resource:
        - "*"

functions:
  first_step:
    handler: simple_lambda.run
  second_step:
    handler: another_lambda.run
    timeout: 5
  machine_invoker:
    handler: state_machine_invoker.run
    events:
      - sns: 'arn:aws:sns:eu-west-1:xxxxxxxx:sns_name'
    custom:
      env-resources:
        - MyStateMachine

stepFunctions:
  stateMachines:
    exampleMachine:
      name: myStateMachine
      definition:
        StartAt: firstStep
        States:
          firstStep:
            Type: Task
            Resource: arn:aws:lambda:#{AWS::Region}:#{AWS::AccountId}:function:${self:service}-${opt:stage}-first_step
            TimeoutSeconds: 6
            Next: secondStep
          secondStep:
            Type: Task
            Resource: arn:aws:lambda:#{AWS::Region}:#{AWS::AccountId}:function:${self:service}-${opt:stage}-second_step
            TimeoutSeconds: 5
            End: true

plugins:
  - serverless-step-functions
  - serverless-pseudo-parameters
  - serverless-resources-env