lambda-saga-pattern

Implements the Saga pattern for Lambda functions using Step Functions.

The example is based on Catie McCaffrey's example in her talk on Applying the Saga pattern.

Each request has a compensating request for rollback.

The Saga goes like this:

Begin saga
  Start book hotel request
  End book hotel request
  Start book flight request
  End book flight request
  Start book car rental request
  End book car rental request  
End saga

Deployment

Steps to set up the Distribution

a. Build lambda function, and prepare them for subsequent steps in the workflow

  Command: sam build -b ./build -s . -t template.yaml -u

b. Packages the above LambdaFunction. It creates a ZIP file of the code and dependencies, and uploads it to Amazon S3 (please create the S3 bucket and mention the bucket name in the command below). It then returns a copy of AWS SAM template, replacing references to local artifacts with the Amazon S3 location where the command uploaded the artifacts

  Command: sam package \
            --template-file build/template.yaml \
            --s3-bucket viyoma-private-s3 \
            --output-template-file build/packaged.yaml

c. Deploy Lambda functions through AWS CloudFormation from the S3 bucket created above. AWS SAM CLI now creates and manages this Amazon S3 bucket for you.

  Command:  sam deploy \
            --template-file build/packaged.yaml \
            --stack-name oidc-auth2 \
            --capabilities CAPABILITY_NAMED_IAM 

Steps to set up the State Machine

a. Got to Step Functions and Create a stae Machine using states.json, replace the lambda function Arn's from your ARN's

b. Execute the state Machine for success by the following input:

      {
          "tripId": "5c12d94a-ee6a-40d9-889b-1d49142248b7",
          "depart": "London",
          "departAt": "2017-07-10T06:00:00.000Z",
          "arrive": "Dublin",
          "arriveAt": "2017-07-12T08:00:00.000Z",
          "hotel": "holiday inn",
          "checkIn": "2017-07-10T12:00:00.000Z",
          "checkOut": "2017-07-12T14:00:00.000Z",
          "car": "Volvo",
          "carFrom": "2017-07-10T00:00:00.000Z",
          "carTo": "2017-07-12T00:00:00.000Z"
          }

c. Execute the state Machine for Failure by the following input:

    {
          "tripId": "5c12d94a-ee6a-40d9-889b-1d49142248b7",
          "depart": "London",
          "departAt": "2017-07-10T06:00:00.000Z",
          "arrive": "Dublin",
          "arriveAt": "2017-07-12T08:00:00.000Z",
          "hotel": "holiday inn",
          "checkIn": "2017-07-10T12:00:00.000Z",
          "checkOut": "2017-07-12T14:00:00.000Z",
          "car": "Volvo",
          "carFrom": "2017-07-10T00:00:00.000Z",
          "carTo": "2017-07-12T00:00:00.000Z",
          "failBookFlight": true
          }