09-InvokingStateMachineAPIGateway.md

INVOKING STATE MACHINE WITH API GATEWAY

1. INTRODUCTION

• Using the HelloWorld state machine build previously HelloWorld

2. TRIGGERING THE STATE MACHINE (BY API GATEWAY CONSOLE)

(A) CREATE IAM ROLE FOR EXECUTION ROLE

• Go to IAM
• Go to Roles
• Create a new role
• Choose AWS service
• Under Lambda, choose API Gateway
• Choose Next: Permissions
• Choose AmazonAPIGatewayPushToCloudWatchLogs policy
• Choose Next: Review
• Enter the following data:

Role name => "APIGatewayStepFunctions"
Role description => "Allows API Gateway to push logs to CloudWatch Logs."

• Choose Create role

(B) ATTACH POLICIES TO THE IAM ROLE CREATED

• Enter the role APIGatewayStepFunctions
• Choose Attach policies
• Filter policy step
• Enable AWSStepFunctionsFullAccess
• Choose Attach policy
• Copy Role ARN identification

(C) ADD HTTP POST METHOD

• Go to API Gateway console

• Enter the Hello World API

• Choose the /math resource

• Add new method (HTTP POST)

• Setup the new method | Field | Value | | :---: | :---: | | Integration type | AWS Service | | AWS Region | us-west-2 | | AWS Service | Step Functions | | HTTP method | POST | | Action Type | Use action name | | Action | StartExecution | | Execution role | Paste the IAM role ARN copied previously | | Content Handling | Passthrough | | Use Default Timeout | Enable |

• Choose Save

• Choose Stages

• Enter the test stage

• Choose the method created

• Copy the Invoke URL

• Deploy the API

3. TEST WITH POSTMAN

(A) REQUEST

• Enter the request URL (HTTP method = POST)
• Under Headers, enter the following

Key = Content-Type
Value = application/json

• Under Body, choose raw (JSON (application/json))
• Enter the following:

{
  "input": "{\"Comment\": \"Invoked from API Gateway\",\"number\": 5}", // input data for the state machine
  "name": "api_gateway_test_1", // unique name for the state machine execution
  "stateMachineArn": "arn:aws:states:us-west-2:0123456789:stateMachine:Helloworld" // ARN for desired state machine
}

• Choose Save
• Send the request

(B) RESPONSE

• Execution has started successfully

{
  "executionArn": "arn:aws:states:us-west-2:0123456789:execution:Helloworld:api_gateway_test_1",
  "startDate": 1537116811.05
}

4. BIBLIOGRAPHICAL REFERENCES

• [1] Creating a Step Functions API using API Gateway