Create & Deploy an AWS State Machine with a .NET Core Lambda using AWS SAM

by Harish KM

This article explains how to create & deploy an AWS State Machine with a .NET Core Lambda using AWS SAM.

Prerequisites

  • Latest AWS CLI. This guide uses v2.0.19.
  • Latest SAM CLI. This guide uses v0.39.0.
  • VS Code with AWS Toolkit. This guide uses VS Code v1.45.1 with AWS Toolkit v1.10.0.
  • Latest .NET Core SDK. This guide uses v3.1.300.

Step 1 — Create SAM App

In VS Code:

Select .NET Core:

Select Hello World:

Select a folder:

Name the app:

The app is created & the template is displayed:

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  Sample SAM Template for sam-app

# More info about Globals: https://github.com/awslabs/serverless-application-model/blob/master/docs/globals.rst
Globals:
  Function:
    Timeout: 10

Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    Properties:
      CodeUri: ./src/HelloWorld/
      Handler: HelloWorld::HelloWorld.Function::FunctionHandler
      Runtime: dotnetcore2.1
      Environment: # More info about Env Vars: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#environment-object
        Variables:
          PARAM1: VALUE
      Events:
        HelloWorld:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /hello
            Method: get

Outputs:
  # ServerlessRestApi is an implicit API created out of Events key under Serverless::Function
  # Find out more about other implicit resources you can reference within SAM
  # https://github.com/awslabs/serverless-application-model/blob/master/docs/internals/generated_resources.rst#api
  HelloWorldApi:
    Description: "API Gateway endpoint URL for Prod stage for Hello World function"
    Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/hello/"
  HelloWorldFunction:
    Description: "Hello World Lambda Function ARN"
    Value: !GetAtt HelloWorldFunction.Arn
  HelloWorldFunctionIamRole:
    Description: "Implicit IAM Role created for Hello World function"
    Value: !GetAtt HelloWorldFunctionRole.Arn

Delete the highlighted lines above.

Step 2 — Add State Machine

Add the following between lines 11 & 12 in the template:

  StateMachine:
    Type: AWS::Serverless::StateMachine
    Properties:
      Definition:
        StartAt: HelloWorldLambdaState
        States:
          HelloWorldLambdaState:
            Type: Task
            Resource: !GetAtt HelloWorldFunction.Arn
            End: true
      Policies:
      - LambdaInvokePolicy:
          FunctionName: !Ref HelloWorldFunction

Step 3 — Deploy SAM App

In VS Code:

Select template:

Select region:

Provide an S3 bucket:

Name the CloudFormation stack:

Wait for deployment:

Starting SAM Application deployment...
Building SAM Application...
Packaging SAM Application to S3 Bucket: sam-app-code-c6ba893e
Deploying SAM Application to CloudFormation Stack: sam-app-stack
Successfully deployed SAM Application to CloudFormation Stack: sam-app-stack

Step 4 — Test State Machine

Open the state machine in AWS console & start execution:

In a few seconds, the execution completes & output is displayed: