template.yaml

# Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: MIT-0

---
AWSTemplateFormatVersion: '2010-09-09'

Transform: 'AWS::Serverless-2016-10-31'

Description: AWS AppSync Long Running Query

Resources:
  ## AppSync ##
  SearchApi:
    Type: AWS::AppSync::GraphQLApi
    Properties:
      AuthenticationType: API_KEY
      Name: SearchApi

  SearchApiKey:
    Type: AWS::AppSync::ApiKey
    Properties:
      ApiId: !GetAtt SearchApi.ApiId
      Description: API Key for Search API

  MessagesSchema:
    Type: AWS::AppSync::GraphQLSchema
    Properties:
      ApiId: !GetAtt SearchApi.ApiId
      DefinitionS3Location: schema.graphql


  SearchQueryResolver:
    Type: AWS::AppSync::Resolver
    Properties:
      ApiId: !GetAtt SearchApi.ApiId
      TypeName: Query
      FieldName: search
      DataSourceName: !GetAtt StepFunctionsHttpDataSource.Name
      # Generate a unique execution id for the step function execution so
      # that it can be passed through to Lambda on Step Function start.
      # Use context stash so it is also available in response mapping.
      RequestMappingTemplate: !Sub |
        $util.qr($ctx.stash.put("executionId", $util.autoId()))

        {
          "version": "2018-05-29",
          "method": "POST",
          "resourcePath": "/",
          "params": {
            "headers": {
              "content-type": "application/x-amz-json-1.0",
              "x-amz-target":"AWSStepFunctions.StartExecution"
            },
            "body": {
              "stateMachineArn": "${SearchStateMachine}",
              "input": "{ \"name\": \"$ctx.stash.executionId\" }"
            }
          }
        }
      # Return the execution id from Step Functions for client to subscribe.
      ResponseMappingTemplate: |
        {
          "id": "${ctx.stash.executionId}",
          "status": "PENDING"
        }

  PublishResultMutationResolver:
    Type: AWS::AppSync::Resolver
    Properties:
      ApiId: !GetAtt SearchApi.ApiId
      TypeName: Mutation
      FieldName: publishResult
      DataSourceName: !GetAtt PublishResultDataSource.Name
      RequestMappingTemplate: |
        {
          "version": "2017-02-28",
          "payload": {
            "id": "${ctx.arguments.result.id}",
            "status": "${ctx.arguments.result.status}",
            "listings": "${ctx.arguments.result.listings}"
          }
        }
      ResponseMappingTemplate: |
        $util.toJson($ctx.arguments.result)

  StepFunctionsHttpDataSource:
    Type: AWS::AppSync::DataSource
    Properties:
      ApiId: !GetAtt SearchApi.ApiId
      Name: StepFunctionsHttpDataSource
      Description: Step Functions HTTP
      Type: HTTP
      ServiceRoleArn: !GetAtt AppSyncServiceRole.Arn
      HttpConfig:
        Endpoint: !Sub https://states.${AWS::Region}.amazonaws.com/
        AuthorizationConfig:
          AuthorizationType: AWS_IAM
          AwsIamConfig:
            SigningRegion: !Ref AWS::Region
            SigningServiceName: states

  PublishResultDataSource:
    Type: AWS::AppSync::DataSource
    Properties:
      ApiId: !GetAtt SearchApi.ApiId
      Name: PublishResultDataSource
      Description: Local data source to publish results
      Type: NONE
  
  SearchStateMachine:
    Type: AWS::StepFunctions::StateMachine
    Properties:
      StateMachineName: aws-appsync-long-query-search
      RoleArn: !GetAtt SearchStateMachineRole.Arn
      DefinitionString: !Sub |
        {
          "Comment": "Wait and return a result",
          "StartAt": "Wait For One Minute",
          "States": {
            "Wait For One Minute": {
              "Type": "Wait",
              "Seconds": 60,
              "Next": "Return Result"
            },
            "Return Result": {
              "Type": "Task",
              "Resource": "${ReturnResultFunction.Arn}",
              "ResultPath": "$",
              "TimeoutSeconds": 10,
              "Catch": [{
                "ErrorEquals": [ "States.ALL" ],
                "ResultPath": "$.error",
                "Next": "HandleError"
              }],
              "End": true
            },
            "HandleError": {
              "Type": "Fail",
              "Cause": "$.error"
            }
          }
        }
    
  ReturnResultFunction:
    Type: AWS::Serverless::Function
    Properties:
      Description: Returns a result by calling AppSync mutation, triggering subscription
      CodeUri: result/
      Runtime: nodejs10.x
      Handler: index.handler
      Timeout: 10
      Environment:
        Variables:
          APPSYNC_API_KEY: !GetAtt SearchApiKey.ApiKey
          APPSYNC_ENDPOINT: !GetAtt SearchApi.GraphQLUrl
          

  #
  # IAM
  #
  SearchStateMachineRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service: !Sub states.${AWS::Region}.amazonaws.com
            Action: sts:AssumeRole
      Path: /long-query/
      Policies:
        - PolicyName: StatesExecutionPolicy
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Action:
                  - lambda:InvokeFunction
                Resource:
                  - !GetAtt ReturnResultFunction.Arn

  AppSyncServiceRole:
    Type: AWS::IAM::Role
    Properties:
      Path: /long-query/
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSAppSyncPushToCloudWatchLogs
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Action:
              - sts:AssumeRole
            Principal:
              Service:
                - appsync.amazonaws.com
      Policies:
        - PolicyName: appsync-long-query-service-policy
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Action:
                  - states:StartExecution
                Resource:
                  - !Ref SearchStateMachine

Outputs:
  ApiEndpoint:
    Description: AppSync Endpoint
    Value: !GetAtt SearchApi.GraphQLUrl
  
  ApiId:
    Description: AppSync API ID
    Value: !GetAtt SearchApi.ApiId

  ApiKey:
    Description: AppSync API Key
    Value: !GetAtt SearchApiKey.ApiKey