Azure Pipelines: CI/CD

Azure Pipelines is the CI/CD engine within Azure DevOps. It automates the process of building, testing, and deploying your applications to any platform, cloud, or on-premises environment. With YAML-based pipeline definitions, your CI/CD configuration lives alongside your code, making it version-controlled, reviewable, and repeatable.

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Continuous Integration (CI)

CI is the practice of automatically building and testing code every time a developer pushes changes. The goal is to catch issues early and maintain a deployable codebase.

What CI Does

1. Trigger — a developer pushes code or opens a pull request
2. Build — the pipeline compiles the code and resolves dependencies
3. Test — automated tests run (unit, integration, linting)
4. Publish — build artifacts are stored for deployment

Basic CI Pipeline

# azure-pipelines.yml
trigger:
  branches:
    include:
      - main
      - feature/*

pool:
  vmImage: 'ubuntu-latest'

steps:
  - task: NodeTool@0
    inputs:
      versionSpec: '20.x'
    displayName: 'Install Node.js'

  - script: npm ci
    displayName: 'Install dependencies'

  - script: npm run lint
    displayName: 'Run linter'

  - script: npm test -- --coverage
    displayName: 'Run tests'

  - task: PublishTestResults@2
    inputs:
      testResultsFormat: 'JUnit'
      testResultsFiles: '**/junit.xml'
    displayName: 'Publish test results'

  - task: PublishCodeCoverageResults@2
    inputs:
      summaryFileLocation: '**/coverage/cobertura-coverage.xml'
    displayName: 'Publish code coverage'

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Continuous Deployment (CD)

CD extends CI by automatically deploying the build artifacts to one or more environments:

Code Push → Build → Test → Deploy to Staging → Approval → Deploy to Production

Multi-Stage Pipeline

trigger:
  branches:
    include:
      - main

stages:
  - stage: Build
    jobs:
      - job: BuildApp
        pool:
          vmImage: 'ubuntu-latest'
        steps:
          - script: npm ci && npm run build
            displayName: 'Build application'
          - publish: $(System.DefaultWorkingDirectory)/dist
            artifact: app-build

  - stage: DeployStaging
    dependsOn: Build
    jobs:
      - deployment: DeployToStaging
        environment: staging
        strategy:
          runOnce:
            deploy:
              steps:
                - download: current
                  artifact: app-build
                - task: AzureWebApp@1
                  inputs:
                    azureSubscription: 'my-service-connection'
                    appName: 'webapp-staging'
                    package: '$(Pipeline.Workspace)/app-build'

  - stage: DeployProduction
    dependsOn: DeployStaging
    jobs:
      - deployment: DeployToProduction
        environment: production
        strategy:
          runOnce:
            deploy:
              steps:
                - download: current
                  artifact: app-build
                - task: AzureWebApp@1
                  inputs:
                    azureSubscription: 'my-service-connection'
                    appName: 'webapp-production'
                    package: '$(Pipeline.Workspace)/app-build'

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Pipeline Triggers

Trigger Type	Description
CI trigger	Runs on push to specified branches
PR trigger	Runs when a pull request is opened or updated
Scheduled	Runs on a cron schedule
Pipeline trigger	Runs when another pipeline completes
Manual	Triggered manually from the Azure DevOps UI

# Scheduled trigger — nightly build
schedules:
  - cron: '0 2 * * *'
    displayName: 'Nightly build'
    branches:
      include:
        - main
    always: true

# PR trigger
pr:
  branches:
    include:
      - main
  paths:
    exclude:
      - docs/*
      - '*.md'

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Agents

Agents are the machines that execute your pipeline:

Agent Type	Description	Best For
Microsoft-hosted	Pre-configured VMs managed by Microsoft (Ubuntu, Windows, macOS)	Standard builds, no maintenance
Self-hosted	Your own machines (physical, VM, or container)	Custom tooling, compliance, network access

Microsoft-Hosted Agent Images

Image	OS
ubuntu-latest	Ubuntu 22.04 LTS
windows-latest	Windows Server 2022
macos-latest	macOS 14 (Sonoma)

Self-Hosted Agent Pools

# Register a self-hosted agent
./config.sh --unattended \
  --url https://dev.azure.com/myorg \
  --auth pat \
  --token <PAT> \
  --pool "Linux Agents" \
  --agent "agent-01"

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Variables and Secrets