StepFunctionsで承認ジョブを作成する

AWSTemplateFormatVersion: "2010-09-09"
Description: "AWS Step Functions Human based task example. It sends an email with an HTTP URL for approval."
Parameters:
  Email:
    Type: String
    AllowedPattern: "^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+$"
    ConstraintDescription: Must be a valid email address.
Resources:
  # Begin API Gateway Resources
  ExecutionApi:
    Type: "AWS::ApiGateway::RestApi"
    Properties:
      Name: "Human approval endpoint"
      Description: "HTTP Endpoint backed by API Gateway and Lambda"
      FailOnWarnings: true

  ExecutionResource:
    Type: 'AWS::ApiGateway::Resource'
    Properties:
      RestApiId: !Ref ExecutionApi
      ParentId: !GetAtt "ExecutionApi.RootResourceId"
      PathPart: execution

  ExecutionMethod:
    Type: "AWS::ApiGateway::Method"
    Properties:
      AuthorizationType: NONE
      HttpMethod: GET
      Integration:
        Type: AWS
        IntegrationHttpMethod: POST
        Uri: !Sub "arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${LambdaApprovalFunction.Arn}/invocations"
        IntegrationResponses:
          - StatusCode: 302
            ResponseParameters:
              method.response.header.Location: "integration.response.body.headers.Location"
        RequestTemplates:
          application/json: |
            {
              "body" : $input.json('$'),
              "headers": {
                #foreach($header in $input.params().header.keySet())
                "$header": "$util.escapeJavaScript($input.params().header.get($header))" #if($foreach.hasNext),#end

                #end
              },
              "method": "$context.httpMethod",
              "params": {
                #foreach($param in $input.params().path.keySet())
                "$param": "$util.escapeJavaScript($input.params().path.get($param))" #if($foreach.hasNext),#end

                #end
              },
              "query": {
                #foreach($queryParam in $input.params().querystring.keySet())
                "$queryParam": "$util.escapeJavaScript($input.params().querystring.get($queryParam))" #if($foreach.hasNext),#end

                #end
              }  
            }
      ResourceId: !Ref ExecutionResource
      RestApiId: !Ref ExecutionApi
      MethodResponses:
        - StatusCode: 302
          ResponseParameters:
            method.response.header.Location: true

  ApiGatewayAccount:
    Type: 'AWS::ApiGateway::Account'
    Properties:
      CloudWatchRoleArn: !GetAtt "ApiGatewayCloudWatchLogsRole.Arn"
  
  ApiGatewayCloudWatchLogsRole:
    Type: 'AWS::IAM::Role'
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - apigateway.amazonaws.com
            Action:
              - 'sts:AssumeRole'
      Policies:
        - PolicyName: ApiGatewayLogsPolicy
          PolicyDocument:
            Version: 2012-10-17
            Statement:
              - Effect: Allow
                Action:
                  - "logs:*"
                Resource: !Sub "arn:${AWS::Partition}:logs:*:*:*"

  ExecutionApiStage:
    DependsOn:
      - ApiGatewayAccount
    Type: 'AWS::ApiGateway::Stage'
    Properties:
      DeploymentId: !Ref ApiDeployment
      MethodSettings:
        - DataTraceEnabled: true
          HttpMethod: '*'
          LoggingLevel: INFO
          ResourcePath: /*
      RestApiId: !Ref ExecutionApi
      StageName: states

  ApiDeployment:
    Type: "AWS::ApiGateway::Deployment"
    DependsOn:
      - ExecutionMethod
    Properties:
      RestApiId: !Ref ExecutionApi
      StageName: DummyStage
  # End API Gateway Resources

  # Begin
  # Lambda that will be invoked by API Gateway
  LambdaApprovalFunction:
    Type: 'AWS::Lambda::Function'
    Properties:
      Code:
        ZipFile:
          Fn::Sub: |
            const { SFN: StepFunctions } = require("@aws-sdk/client-sfn");
            var redirectToStepFunctions = function(lambdaArn, statemachineName, executionName, callback) {
              const lambdaArnTokens = lambdaArn.split(":");
              const partition = lambdaArnTokens[1];
              const region = lambdaArnTokens[3];
              const accountId = lambdaArnTokens[4];

              console.log("partition=" + partition);
              console.log("region=" + region);
              console.log("accountId=" + accountId);

              const executionArn = "arn:" + partition + ":states:" + region + ":" + accountId + ":execution:" + statemachineName + ":" + executionName;
              console.log("executionArn=" + executionArn);

              const url = "https://console.aws.amazon.com/states/home?region=" + region + "#/executions/details/" + executionArn;
              callback(null, {
                  statusCode: 302,
                  headers: {
                    Location: url
                  }
              });
            };

            exports.handler = (event, context, callback) => {
              console.log('Event= ' + JSON.stringify(event));
              const action = event.query.action;
              const taskToken = event.query.taskToken;
              const statemachineName = event.query.sm;
              const executionName = event.query.ex;

              const stepfunctions = new StepFunctions();

              var message = "";

              if (action === "approve") {
                message = { "Status": "Approved! Task approved by ${Email}" };
              } else if (action === "reject") {
                message = { "Status": "Rejected! Task rejected by ${Email}" };
              } else {
                console.error("Unrecognized action. Expected: approve, reject.");
                callback({"Status": "Failed to process the request. Unrecognized Action."});
              }

              stepfunctions.sendTaskSuccess({
                output: JSON.stringify(message),
                taskToken: event.query.taskToken
              })
              .then(function(data) {
                redirectToStepFunctions(context.invokedFunctionArn, statemachineName, executionName, callback);
              }).catch(function(err) {
                console.error(err, err.stack);
                callback(err);
              });
            }
      Description: Lambda function that callback to AWS Step Functions
      FunctionName: LambdaApprovalFunction
      Handler: index.handler
      Role: !GetAtt "LambdaApiGatewayIAMRole.Arn"
      Runtime: nodejs18.x

  LambdaApiGatewayInvoke:
    Type: "AWS::Lambda::Permission"
    Properties:
      Action: "lambda:InvokeFunction"
      FunctionName: !GetAtt "LambdaApprovalFunction.Arn"
      Principal: "apigateway.amazonaws.com"
      SourceArn: !Sub "arn:aws:execute-api:${AWS::Region}:${AWS::AccountId}:${ExecutionApi}/*"

  LambdaApiGatewayIAMRole:
    Type: "AWS::IAM::Role"
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Action:
              - "sts:AssumeRole"
            Effect: "Allow"
            Principal:
              Service:
                - "lambda.amazonaws.com"
      Policies:
        - PolicyName: CloudWatchLogsPolicy
          PolicyDocument:
            Statement:
              - Effect: Allow
                Action:
                  - "logs:*"
                Resource: !Sub "arn:${AWS::Partition}:logs:*:*:*"
        - PolicyName: StepFunctionsPolicy
          PolicyDocument:
            Statement:
              - Effect: Allow
                Action:
                  - "states:SendTaskFailure"
                  - "states:SendTaskSuccess"
                Resource: "*"
  # End Lambda that will be invoked by API Gateway

  # Begin state machine that publishes to Lambda and sends an email with the link for approval
  HumanApprovalLambdaStateMachine:
    Type: AWS::StepFunctions::StateMachine
    Properties:
      RoleArn: !GetAtt LambdaStateMachineExecutionRole.Arn
      DefinitionString:
        Fn::Sub: |
          {
              "StartAt": "Lambda Callback",
              "TimeoutSeconds": 3600,
              "States": {
                  "Lambda Callback": {
                      "Type": "Task",
                      "Resource": "arn:${AWS::Partition}:states:::lambda:invoke.waitForTaskToken",
                      "Parameters": {
                        "FunctionName": "${LambdaHumanApprovalSendEmailFunction.Arn}",
                        "Payload": {
                          "ExecutionContext.$": "$$",
                          "APIGatewayEndpoint": "https://${ExecutionApi}.execute-api.${AWS::Region}.amazonaws.com/states"
                        }
                      },
                      "Next": "ManualApprovalChoiceState"
                  },
                  "ManualApprovalChoiceState": {
                    "Type": "Choice",
                    "Choices": [
                      {
                        "Variable": "$.Status",
                        "StringEquals": "Approved! Task approved by ${Email}",
                        "Next": "ApprovedPassState"
                      },
                      {
                        "Variable": "$.Status",
                        "StringEquals": "Rejected! Task rejected by ${Email}",
                        "Next": "RejectedPassState"
                      }
                    ]
                  },
                  "ApprovedPassState": {
                    "Type": "Pass",
                    "End": true
                  },
                  "RejectedPassState": {
                    "Type": "Pass",
                    "End": true
                  }
              }
          }

  SNSHumanApprovalEmailTopic:
    Type: AWS::SNS::Topic
    Properties:
      Subscription:
        -
           Endpoint: !Sub ${Email}
           Protocol: email
  
  LambdaHumanApprovalSendEmailFunction:
    Type: "AWS::Lambda::Function"
    Properties:
      Handler: "index.lambda_handler"
      Role: !GetAtt LambdaSendEmailExecutionRole.Arn
      Runtime: "nodejs18.x"
      Timeout: "25"
      Code:
        ZipFile:
          Fn::Sub: |
            console.log('Loading function');
            const { SNS } = require("@aws-sdk/client-sns");
            exports.lambda_handler = (event, context, callback) => {
                console.log('event= ' + JSON.stringify(event));
                console.log('context= ' + JSON.stringify(context));

                const executionContext = event.ExecutionContext;
                console.log('executionContext= ' + executionContext);

                const executionName = executionContext.Execution.Name;
                console.log('executionName= ' + executionName);

                const statemachineName = executionContext.StateMachine.Name;
                console.log('statemachineName= ' + statemachineName);

                const taskToken = executionContext.Task.Token;
                console.log('taskToken= ' + taskToken);

                const apigwEndpint = event.APIGatewayEndpoint;
                console.log('apigwEndpint = ' + apigwEndpint)

                const approveEndpoint = apigwEndpint + "/execution?action=approve&ex=" + executionName + "&sm=" + statemachineName + "&taskToken=" + encodeURIComponent(taskToken);
                console.log('approveEndpoint= ' + approveEndpoint);

                const rejectEndpoint = apigwEndpint + "/execution?action=reject&ex=" + executionName + "&sm=" + statemachineName + "&taskToken=" + encodeURIComponent(taskToken);
                console.log('rejectEndpoint= ' + rejectEndpoint);

                const emailSnsTopic = "${SNSHumanApprovalEmailTopic}";
                console.log('emailSnsTopic= ' + emailSnsTopic);

                var emailMessage = 'Welcome! \n\n';
                emailMessage += 'This is an email requiring an approval for a step functions execution. \n\n'
                emailMessage += 'Please check the following information and click "Approve" link if you want to approve. \n\n'
                emailMessage += 'Execution Name -> ' + executionName + '\n\n'
                emailMessage += 'Approve ' + approveEndpoint + '\n\n'
                emailMessage += 'Reject ' + rejectEndpoint + '\n\n'
                emailMessage += 'Thanks for using Step functions!'
                
                const sns = new SNS();
                var params = {
                  Message: emailMessage,
                  Subject: "Required approval from AWS Step Functions",
                  TopicArn: emailSnsTopic
                };

                sns.publish(params)
                  .then(function(data) {
                    console.log("MessageID is " + data.MessageId);
                    callback(null);
                  }).catch(
                    function(err) {
                    console.error(err, err.stack);
                    callback(err);
                  });
            }

  LambdaStateMachineExecutionRole:
    Type: "AWS::IAM::Role"
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service: states.amazonaws.com
            Action: "sts:AssumeRole"
      Policies:
        - PolicyName: InvokeCallbackLambda
          PolicyDocument:
            Statement:
              - Effect: Allow
                Action:
                  - "lambda:InvokeFunction"
                Resource:
                  - !Sub "${LambdaHumanApprovalSendEmailFunction.Arn}"

  LambdaSendEmailExecutionRole:
    Type: "AWS::IAM::Role"
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: "sts:AssumeRole"
      Policies:
        - PolicyName: CloudWatchLogsPolicy
          PolicyDocument:
            Statement:
              - Effect: Allow
                Action:
                  - "logs:CreateLogGroup"
                  - "logs:CreateLogStream"
                  - "logs:PutLogEvents"
                Resource: !Sub "arn:${AWS::Partition}:logs:*:*:*"
        - PolicyName: SNSSendEmailPolicy
          PolicyDocument:
            Statement:
              - Effect: Allow
                Action:
                  - "SNS:Publish"
                Resource:
                  - !Sub "${SNSHumanApprovalEmailTopic}"

# End state machine that publishes to Lambda and sends an email with the link for approval
Outputs:
  ApiGatewayInvokeURL:
    Value: !Sub "https://${ExecutionApi}.execute-api.${AWS::Region}.amazonaws.com/states"
  StateMachineHumanApprovalArn:
    Value: !Ref HumanApprovalLambdaStateMachine