Add CodeCommit PR commenting to CloudFormation template

Author: clareliguori

cloudformation/continuous-integration-pull-request-checks.yml

@@ -1,4 +1,5 @@
 AWSTemplateFormatVersion: 2010-09-09
+Transform: 'AWS::Serverless-2016-10-31'
 
 Description: Perform continuous integration pull request checks on a CodeCommit repository with CodeBuild
 
@@ -196,3 +197,45 @@ Resources:
         - - !Ref 'AWS::StackName'
           - CodeBuild
     Type: AWS::IAM::Role
+
+  PullRequestBuildComments:
+    Type: 'AWS::Serverless::Function'
+    Properties:
+      Handler: codecommit_pr_notifications.handler
+      Runtime: nodejs8.10
+      CodeUri: ../ci_tools
+      Description: >-
+        Comment on the CodeCommit pull request when a build is triggered and when it completes
+      Policies:
+        - AWSLambdaBasicExecutionRole
+        - Version: '2012-10-17'
+          Statement:
+            - Effect: Allow
+              Action:
+                - codecommit:PostCommentForPullRequest
+              Resource:
+                - !Join
+                  - ':'
+                  - - arn
+                    - aws
+                    - codecommit
+                    - !Ref 'AWS::Region'
+                    - !Ref 'AWS::AccountId'
+                    - !Ref CodeCommitRepoName
+            - Effect: Allow
+              Action:
+                - logs:GetLogEvents
+              Resource: !Sub "arn:aws:logs:${AWS::Region}:${AWS::AccountId}:log-group:/aws/codebuild/*"
+      Events:
+        BuildTrigger:
+          Type: CloudWatchEvent
+          Properties:
+            Pattern:
+              source:
+                - aws.codebuild
+              detail-type:
+                - CodeBuild Build State Change
+              detail:
+                additional-information:
+                  initiator:
+                    - !Sub "rule/${SourceEvent}"