dotnet-ado-patterns

Composable Azure DevOps YAML pipeline patterns for .NET projects: template references with extends, stages, jobs, and steps keywords for hierarchical pipeline composition, variable groups and variable templates for centralized configuration, pipeline decorators for organization-wide policy injection, conditional insertion with ${{ if }} and ${{ each }} expressions, multi-stage pipelines (build, test, deploy), and pipeline triggers for CI, PR, and scheduled runs.

Version assumptions: Azure Pipelines YAML schema. DotNetCoreCLI@2 task for .NET 8/9/10 builds. Template expressions syntax v2.

Scope boundary: This skill owns composable pipeline design patterns for Azure DevOps YAML. Starter CI templates (basic build/test/pack) are owned by [skill:dotnet-add-ci] -- this skill extends those templates with advanced composition. CLI-specific release pipelines (build-package-release for CLI binaries) are owned by [skill:dotnet-cli-release-pipeline] -- this skill covers general pipeline patterns that CLI pipelines consume. ADO-unique features (environments with approvals, service connections, classic releases) are in [skill:dotnet-ado-unique].

Out of scope: Starter CI templates -- see [skill:dotnet-add-ci]. CLI release pipelines (tag-triggered build-package-release for CLI tools) -- see [skill:dotnet-cli-release-pipeline]. ADO-unique features (environments, service connections, classic releases) -- see [skill:dotnet-ado-unique]. Build/test specifics -- see [skill:dotnet-ado-build-test]. Publishing pipelines -- see [skill:dotnet-ado-publish]. GitHub Actions workflow patterns -- see [skill:dotnet-gha-patterns].

Cross-references: [skill:dotnet-add-ci] for starter templates that these patterns extend, [skill:dotnet-cli-release-pipeline] for CLI-specific release automation.

---

Template References

Stage Templates

Stage templates define reusable pipeline stages that callers insert into their multi-stage pipeline:

# templates/stages/build-test.yml
parameters:
  - name: dotnetVersion
    type: string
    default: '8.0.x'
  - name: buildConfiguration
    type: string
    default: 'Release'
  - name: projects
    type: string
    default: '**/*.sln'

stages:
  - stage: Build
    displayName: 'Build and Test'
    jobs:
      - job: BuildJob
        pool:
          vmImage: 'ubuntu-latest'
        steps:
          - task: UseDotNet@2
            displayName: 'Install .NET SDK'
            inputs:
              packageType: 'sdk'
              version: ${{ parameters.dotnetVersion }}

          - task: DotNetCoreCLI@2
            displayName: 'Restore'
            inputs:
              command: 'restore'
              projects: ${{ parameters.projects }}

          - task: DotNetCoreCLI@2
            displayName: 'Build'
            inputs:
              command: 'build'
              projects: ${{ parameters.projects }}
              arguments: '-c ${{ parameters.buildConfiguration }} --no-restore'

Calling a Stage Template

# azure-pipelines.yml
trigger:
  branches:
    include:
      - main

stages:
  - template: templates/stages/build-test.yml
    parameters:
      dotnetVersion: '9.0.x'
      buildConfiguration: 'Release'
      projects: 'MyApp.sln'

  - template: templates/stages/deploy.yml
    parameters:
      environment: 'staging'

Job Templates

Job templates encapsulate a complete job with its pool and steps:

# templates/jobs/dotnet-build.yml
parameters:
  - name: dotnetVersion
    type: string
    default: '8.0.x'
  - name: projects
    type: string

jobs:
  - job: Build
    pool:
      vmImage: 'ubuntu-latest'
    steps:
      - task: UseDotNet@2
        inputs:
          packageType: 'sdk'
          version: ${{ parameters.dotnetVersion }}

      - task: DotNetCoreCLI@2
        displayName: 'Build'
        inputs:
          command: 'build'
          projects: ${{ parameters.projects }}
          arguments: '-c Release'

Step Templates

Step templates define reusable step sequences inserted into an existing job:

# templates/steps/dotnet-setup.yml
parameters:
  - name: dotnetVersion
    type: string
    default: '8.0.x'
  - name: nugetFeed
    type: string
    default: ''

steps:
  - task: UseDotNet@2
    displayName: 'Install .NET SDK ${{ parameters.dotnetVersion }}'
    inputs:
      packageType: 'sdk'
      version: ${{ parameters.dotnetVersion }}

  - ${{ if ne(parameters.nugetFeed, '') }}:
    - task: NuGetAuthenticate@1
      displayName: 'Authenticate NuGet feed'

  - task: DotNetCoreCLI@2
    displayName: 'Restore packages'
    inputs:
      command: 'restore'
      projects: '**/*.sln'
      ${{ if ne(parameters.nugetFeed, '') }}:
        feedsToUse: 'select'
        vstsFeed: ${{ parameters.nugetFeed }}

Using Step Templates in a Pipeline

jobs:
  - job: Build
    pool:
      vmImage: 'ubuntu-latest'
    steps:
      - checkout: self

      - template: templates/steps/dotnet-setup.yml
        parameters:
          dotnetVersion: '9.0.x'
          nugetFeed: 'MyOrg/MyFeed'

      - task: DotNetCoreCLI@2
        displayName: 'Build'
        inputs:
          command: 'build'
          arguments: '-c Release --no-restore'

Extends Templates (Enforced Pipeline Structure)

The extends keyword enforces a required pipeline structure defined by an organization template. Callers cannot bypass the structure:

# templates/pipeline-policy.yml
parameters:
  - name: stages
    type: stageList
    default: []

stages:
  - stage: SecurityScan
    displayName: 'Security Scan (Required)'
    jobs:
      - job: Scan
        pool:
          vmImage: 'ubuntu-latest'
        steps:
          - script: echo "Running mandatory security scan"

  - ${{ each stage in parameters.stages }}:
    - ${{ stage }}

  - stage: Compliance
    displayName: 'Compliance Check (Required)'
    dependsOn:
      - ${{ each stage in parameters.stages }}:
        - ${{ stage.stage }}
    jobs:
      - job: Check
        pool:
          vmImage: 'ubuntu-latest'
        steps:
          - script: echo "Running compliance checks"

# azure-pipelines.yml (caller)
extends:
  template: templates/pipeline-policy.yml
  parameters:
    stages:
      - stage: Build
        jobs:
          - job: BuildApp
            pool:
              vmImage: 'ubuntu-latest'
            steps:
              - script: dotnet build -c Release

The extends template wraps caller-defined stages with mandatory security and compliance stages that cannot be removed.

---

Variable Groups and Variable Templates

Variable Groups

Variable groups centralize configuration shared across multiple pipelines. Link them from Azure Pipelines Library:

variables:
  - group: 'dotnet-build-settings'
  - group: 'nuget-feed-credentials'
  - name: buildConfiguration
    value: 'Release'

Variable Templates

Variable templates define reusable variable sets in YAML files:

# templates/variables/dotnet-defaults.yml
variables:
  dotnetVersion: '8.0.x'
  buildConfiguration: 'Release'
  testResultsDirectory: '$(Build.ArtifactStagingDirectory)/test-results'
  coverageDirectory: '$(Build.ArtifactStagingDirectory)/coverage'

# azure-pipelines.yml
variables:
  - template: templates/variables/dotnet-defaults.yml
  - name: projectPath
    value: 'MyApp.sln'

Variable Group with Key Vault Integration

Link variable groups to Azure Key Vault for secret management. Secrets are fetched at pipeline runtime:

# Reference in pipeline
variables:
  - group: 'kv-production-secrets'  # linked to Azure Key Vault
  - name: nonSecretVar
    value: 'some-value'

steps:
  - script: |
      echo "Using secret from Key Vault"
      # $(sql-connection-string) resolves at runtime from Key Vault
    env:
      CONNECTION_STRING: $(sql-connection-string)

Key Vault-linked variable groups require a service connection with Key Vault access. Secret names in Key Vault map to variable names (hyphens become valid variable characters).

---

Pipeline Decorators

Pipeline decorators inject steps into every pipeline in an organization or project, enforcing policies without modifying individual pipeline files. Decorators are an ADO-exclusive feature with no GitHub Actions equivalent -- see [skill:dotnet-ado-unique] for implementation details including extension manifests, deployment guidance, and use case examples.

---

Conditional Insertion

${{ if }} Expressions

parameters:
  - name: runIntegrationTests
    type: boolean
    default: false
  - name: targetEnvironment
    type: string
    default: 'development'
    values:
      - development
      - staging
      - production

stages:
  - stage: Build
    jobs:
      - job: BuildJob
        steps:
          - script: dotnet build -c Release

  - ${{ if eq(parameters.runIntegrationTests, true) }}:
    - stage: IntegrationTests
      dependsOn: Build
      jobs:
        - job: IntegrationTestJob
          steps:
            - script: dotnet test --filter Category=Integration

  - ${{ if eq(parameters.targetEnvironment, 'production') }}:
    - stage: ApprovalGate
      dependsOn: Build
      jobs:
        - job: WaitForApproval
          pool: server
          steps:
            - task: ManualValidation@0
              inputs:
                notifyUsers: 'release-managers@example.com'
                instructions: 'Approve production deployment'

${{ each }} Iteration

parameters:
  - name: environments
    type: object
    default:
      - name: development
        pool: 'ubuntu-latest'
        approvals: false
      - name: staging
        pool: 'ubuntu-latest'
        approvals: true
      - name: production
        pool: 'ubuntu-latest'
        approvals: true

stages:
  - stage: Build
    jobs:
      - job: BuildJob
        steps:
          - script: dotnet build -c Release

  - ${{ each env in parameters.environments }}:
    - stage: Deploy_${{ env.name }}
      displayName: 'Deploy to ${{ env.name }}'
      dependsOn: Build
      jobs:
        - ${{ if eq(env.approvals, true) }}:
          - job: Approve
            pool: server
            steps:
              - task: ManualValidation@0
                inputs:
                  instructions: 'Approve deployment to ${{ env.name }}'

        - deployment: DeployApp
          pool:
            vmImage: ${{ env.pool }}
          environment: ${{ env.name }}
          strategy:
            runOnce:
              deploy:
                steps:
                  - script: echo "Deploying to ${{ env.name }}"

Conditional Step Insertion Within Templates

# templates/steps/dotnet-test.yml
parameters:
  - name: collectCoverage
    type: boolean
    default: false

steps:
  - task: DotNetCoreCLI@2
    displayName: 'Run tests'
    inputs:
      command: 'test'
      projects: '**/*Tests.csproj'
      ${{ if eq(parameters.collectCoverage, true) }}:
        arguments: '-c Release --collect:"XPlat Code Coverage"'
      ${{ else }}:
        arguments: '-c Release'

  - ${{ if eq(parameters.collectCoverage, true) }}:
    - task: PublishCodeCoverageResults@2
      displayName: 'Publish coverage'
      inputs:
        summaryFileLocation: '$(Agent.TempDirectory)/**/coverage.cobertura.xml'

---

Multi-Stage Pipelines

Build, Test, Deploy Pattern

trigger:
  branches:
    include:
      - main
      - release/*

stages:
  - stage: Build
    displayName: 'Build'
    jobs:
      - job: BuildJob
        pool:
          vmImage: 'ubuntu-latest'
        steps:
          - task: UseDotNet@2
            inputs:
              packageType: 'sdk'
              version: '8.0.x'

          - task: DotNetCoreCLI@2
            displayName: 'Build'
            inputs:
              command: 'build'
              projects: 'MyApp.sln'
              arguments: '-c Release'

          - task: DotNetCoreCLI@2
            displayName: 'Publish'
            inputs:
              command: 'publish'
              projects: 'src/MyApp/MyApp.csproj'
              arguments: '-c Release -o $(Build.ArtifactStagingDirectory)/app'

          - task: PublishPipelineArtifact@1
            displayName: 'Upload artifact'
            inputs:
              targetPath: '$(Build.ArtifactStagingDirectory)/app'
              artifactName: 'app'

  - stage: Test
    displayName: 'Test'
    dependsOn: Build
    jobs:
      - job: UnitTests
        pool:
          vmImage: 'ubuntu-latest'
        steps:
          - task: UseDotNet@2
            inputs:
              packageType: 'sdk'
              version: '8.0.x'

          - task: DotNetCoreCLI@2
            displayName: 'Run tests'
            inputs:
              command: 'test'
              projects: '**/*Tests.csproj'
              arguments: '-c Release --logger "trx;LogFileName=results.trx"'

          - task: PublishTestResults@2
            displayName: 'Publish test results'
            condition: always()
            inputs:
              testResultsFormat: 'VSTest'
              testResultsFiles: '**/results.trx'

  - stage: DeployStaging
    displayName: 'Deploy to Staging'
    dependsOn: Test
    jobs:
      - deployment: DeployStaging
        pool:
          vmImage: 'ubuntu-latest'
        environment: 'staging'
        strategy:
          runOnce:
            deploy:
              steps:
                - download: current
                  artifact: app
                - script: echo "Deploying to staging"

  - stage: DeployProduction
    displayName: 'Deploy to Production'
    dependsOn: DeployStaging
    condition: and(succeeded(), eq(variables['Build.SourceBranch'], 'refs/heads/main'))
    jobs:
      - deployment: DeployProduction
        pool:
          vmImage: 'ubuntu-latest'
        environment: 'production'
        strategy:
          runOnce:
            deploy:
              steps:
                - download: current
                  artifact: app
                - script: echo "Deploying to production"

Stage Dependencies and Conditions

stages:
  - stage: Build
    jobs:
      - job: BuildJob
        steps:
          - script: dotnet build -c Release

  - stage: UnitTests
    dependsOn: Build
    jobs:
      - job: UnitTestJob
        steps:
          - script: dotnet test --filter Category!=Integration

  - stage: IntegrationTests
    dependsOn: Build
    jobs:
      - job: IntegrationTestJob
        steps:
          - script: dotnet test --filter Category=Integration

  # Deploy only if BOTH test stages succeed
  - stage: Deploy
    dependsOn:
      - UnitTests
      - IntegrationTests
    condition: and(succeeded('UnitTests'), succeeded('IntegrationTests'))
    jobs:
      - deployment: DeployApp
        environment: 'production'
        strategy:
          runOnce:
            deploy:
              steps:
                - script: echo "Deploying"

---

Pipeline Triggers

CI Triggers

trigger:
  branches:
    include:
      - main
      - release/*
    exclude:
      - feature/experimental/*
  paths:
    include:
      - src/**
      - tests/**
      - '*.sln'
      - Directory.Build.props
      - Directory.Packages.props
    exclude:
      - docs/**
      - '*.md'
  tags:
    include:
      - 'v*'

PR Triggers

pr:
  branches:
    include:
      - main
      - release/*
  paths:
    include:
      - src/**
      - tests/**
    exclude:
      - docs/**
  drafts: false  # do not trigger on draft PRs

Scheduled Triggers

schedules:
  - cron: '0 6 * * 1-5'
    displayName: 'Weekday nightly build'
    branches:
      include:
        - main
    always: false  # only run if there are changes since last run

  - cron: '0 0 * * 0'
    displayName: 'Weekly full validation'
    branches:
      include:
        - main
    always: true  # run even without changes

Pipeline Resource Triggers

Trigger a pipeline when another pipeline completes:

resources:
  pipelines:
    - pipeline: buildPipeline
      source: 'MyApp-Build'
      trigger:
        branches:
          include:
            - main

stages:
  - stage: DeployAfterBuild
    jobs:
      - deployment: Deploy
        environment: 'staging'
        strategy:
          runOnce:
            deploy:
              steps:
                - download: buildPipeline
                  artifact: app
                - script: echo "Deploying build from upstream pipeline"

---

Agent Gotchas

1. Template parameter types are enforced at compile time -- passing a string where type: boolean is expected causes a validation error before the pipeline runs; always match types exactly.
2. extends templates cannot be overridden -- callers cannot inject steps before or after the mandatory stages; this is by design for policy enforcement.
3. Variable group secrets are not available in template expressions -- ${{ variables.mySecret }} resolves at compile time when secrets are not yet available; use $(mySecret) runtime syntax instead.
4. ${{ each }} iterates at compile time -- the loop generates YAML before the pipeline runs; runtime variables cannot be used as the iteration source.
5. CI and PR triggers are mutually exclusive with trigger: none and pr: none -- omitting both trigger and pr sections enables default CI triggering on all branches; explicitly set trigger: none to disable.
6. Path filters in triggers use repository root-relative paths -- do not prefix paths with / or ./; use src/** not ./src/**.
7. Scheduled triggers always run on the default branch first -- the branches.include filter applies after the schedule fires; the schedule itself is only evaluated from the default branch YAML.
8. Pipeline resource triggers require the source pipeline name, not the YAML file path -- use the pipeline name as shown in ADO, not the azure-pipelines.yml file path.