Selectively triggering a GitHub sourced CodePipeline (only for one file)

pipeline.yaml

# CodePipeline by default runs an execution whenever any change is detected in the configured source repository
# We can use a CodePipeline Webhook resource to filter such executions.
#
# This is a snippet that would be part of a CloudFormation template containing
# a CodePipeline resource (AWS::CodePipeline::Pipeline), named CodePipeline in this case, and 
# assumes the GutHub OAuth token is available in the parameter GitHubOAuthToken.
# Typically a CodePipeline Webhook only contains the $.ref filter to check for 
# the desired branch.
# However we can add up to 4 more filters, each of which can query the incoming webhook payload from Github.
# Such payloads are of the form:
# {
#   ...
#   "commits": [
#     {
#       ...
#       "added": [
#         "addedfile1.txt",
#         ...
#       ],
#       "removed": [
# 
#       ],
#       "modified": [
#         "README.md",
#         "modifiedfile2.txt"
#       ]
#     }
#   ],
#   ...
# }
# ... and so we can query the commits object in a JSON Path expression.
# The example here will therefore only trigger a pipeline if the README.md file is updated
# References:
# https://docs.aws.amazon.com/codepipeline/latest/APIReference/API_WebhookDefinition.html
# https://docs.aws.amazon.com/codepipeline/latest/APIReference/API_WebhookFilterRule.html

  GithubWebhook:
    Type: 'AWS::CodePipeline::Webhook'
    Properties:
      RegisterWithThirdParty: 'true'
      Authentication: GITHUB_HMAC
      AuthenticationConfiguration:
        SecretToken: !Ref GitHubOAuthToken
      Filters:
      - JsonPath: "$.ref"
        MatchEquals: refs/heads/{Branch}
      # Only trigger pipeline if README is updated
      Filters:
      - JsonPath: "$.commits[*].*[?(@ == 'README.md')]"
        MatchEquals: README.md
      TargetPipeline: !Ref CodePipeline
      TargetAction: Source
      TargetPipelineVersion: !GetAtt CodePipeline.Version