azure-pipelines-cleanup-acr.yaml

stages:
- stage: cleanupAcr
  displayName: Cleanup ACR Images for PR
  pool:
    vmImage: ubuntu-latest

  jobs:
  - job: cleanupAcr
    variables:      
      prMergeMessage: 'Merged PR '
      serviceConnection: myAzureServiceConnection
      containerRegistry: myacr
      imageRepository: testservice

    steps:
    - task: AzureCLI@1
      # Build.SourceVersionMessage is only available on step level and not on job or stage level. 
      # The message is not extracted until the job has started and checked out the code
      condition: and(succeeded(), startsWith(variables['Build.SourceVersionMessage'], variables.prMergeMessage))
      inputs:
        azureSubscription: $(serviceConnection)
        scriptLocation: inlineScript
        inlineScript: |
          # Parse PR ID from merge commit message e.g. 'Merged PR 66'
          PR_ID=$(echo "$(Build.SourceVersionMessage)" | grep -Eo "$(prMergeMessage)[0-9]+" | awk '{print $3}')

          if [ -z "$PR_ID" ]; then
            echo "Couldn't parse PR ID from commit message: '$(Build.SourceVersionMessage)'"
          else
            PR_URL="$(System.TeamFoundationCollectionUri)$(System.TeamProject)/_apis/git/pullrequests/$PR_ID?api-version=5.1"
            PR_RESPONSE=$(curl -s -H "Authorization:Bearer $(System.AccessToken)" $PR_URL)

            # Parse PR branch name, e.g. 'feature/my-pr-branch' should be parsed as 'my-pr-branch'
            PR_BRANCH=$(basename $(echo $PR_RESPONSE | jq -r ".sourceRefName"))
            MERGE_STATUS=$(echo $PR_RESPONSE | jq -r ".mergeStatus")

            if [ "$MERGE_STATUS" == "succeeded" ]; then
              # Container image tags are assumed to be in format <REPOSITORY>:<BUILD_ID>-<PR_BRANCH_NAME>
              # If your format is different, please modify the regex below in acr purge filter
              az acr run --registry $(containerRegistry) --timeout 3600 --cmd "acr purge --filter '$(imageRepository):.*-$PR_BRANCH' --ago 1m" /dev/null
            else
              echo "PR is not merged, status: '$MERGE_STATUS'"
            fi            
          fi