Pipeline A: The "Factory" (image-builder-pipeline.yml)

This pipeline's only job is to build, compress, and publish your Docker image artifact. You create this pipeline once in the Azure DevOps UI and link it to this file.

Key Features:

• trigger: paths:: This is critical. The pipeline only runs if the Dockerfile itself changes.
• docker save | gzip -c > ...: We pipe the output of docker save directly into gzip. This is a key optimization. It creates a compressed .tar.gz file, which is much faster to upload and download than an uncompressed .tar.

# image-builder-pipeline.yml
# Use a dynamic build number
name: $(Date:yyyyMMdd)$(Rev:.r)

# Trigger ONLY when the Dockerfile changes
trigger:
  paths:
    include:
      - 'ci/docker/Dockerfile'

pool:
  vmImage: 'aws-ubuntu-latest'

parameters:
- name: phpImageName
  displayName: '[PROJECT-NAME] Docker Image'
  type: string
  default: 'php-build-[PROJECT-NAME]'

stages:
- stage: BuildImage
  displayName: 'Build and Publish Docker Image'
  jobs:
  - job: Build
    displayName: 'Build Docker Image'
    steps:
      - checkout: self

      - script: |
          docker build --pull -t ${{ parameters.phpImageName }} -f ci/docker/Dockerfile .
        displayName: 'Build PHP Docker image'

      # === OPTIMIZATION ===
      # Compress the image with gzip on-the-fly
      - script: |
          mkdir -p $(Build.ArtifactStagingDirectory)
          docker save ${{ parameters.phpImageName }} | gzip -c > $(Build.ArtifactStagingDirectory)/${{ parameters.phpImageName }}.tar.gz
        displayName: 'Export and gzip docker image'

      # Publish the gzipped artifact
      - task: PublishBuildArtifacts@1
        displayName: 'Publish Docker Image Artifact'
        inputs:
          PathtoPublish: '$(Build.ArtifactStagingDirectory)'
          ArtifactName: '${{ parameters.phpImageName }}'