Exploring the anatomy of Pipeline in Azure DevOps

Exploring the anatomy of Pipeline in Azure DevOps

A pipeline in Azure DevOps consists of multiple components that define its structure and behavior. Each component plays a role in orchestrating builds, tests, and deployments.

Here’s a detailed breakdown.

1. Name

The pipeline’s name is an identifier that appears in the Azure DevOps UI to help users distinguish between pipeline runs.

Usage

• Define a name to provide context (e.g., include the branch, build number, or timestamp).

• Can be set dynamically using variables.

  Example

  xxxxxxxxxx
  1
  1
  name: 'MyPipeline-$(Build.BuildId)'
  

• $(Build.BuildId) is a system variable representing the unique build ID.

2. Trigger

Defines when the pipeline should start. Azure Pipelines supports multiple types of triggers.

Types

• Continuous Integration (CI): Triggers on code changes.

• Pull Request (PR): Triggers for PR validation.

• Scheduled: Runs pipelines at specific times.

• Manual: Starts pipelines only on demand.

  Example

  xxxxxxxxxx
  5
  1
  trigger:
  2
  - main
  3
  - develop
  4
  pr:
  5
  - feature/
  

  • CI Trigger: Runs on changes to main and develop.

  • PR Trigger: Runs for PRs targeting branches matching feature/.

3. Variables

Variables store values that can be reused throughout the pipeline.

They can be:

• Static: Hardcoded values.

• Dynamic: System or custom variables generated at runtime.

• Secure: Stored securely in Azure DevOps as secrets.

  Example

  xxxxxxxxxx
  3
  1
  variables:
  2
  buildConfiguration: 'Release'
  3
  isProduction: false
  

  • $(buildConfiguration) is used in steps for configuration settings.

  • $(isProduction) can control conditional logic.

4. Job

A job is a collection of steps that execute on an agent. Pipelines can have multiple jobs running sequentially or in parallel.

Key Features

• Display Name: Human-readable name for the job.

• Dependencies: Specify dependencies between jobs.

• Conditionals: Execute jobs conditionally based on variables.

  Example

  xxxxxxxxxx
  5
  1
  jobs:
  2
  - job: BuildJob
  3
  displayName: 'Build the application'
  4
  steps:
  5
    - script: echo Building...
  

5. Pool

The pool specifies the agent (VM) to execute the job.

Azure DevOps offers:

• Microsoft-Hosted Agents: Preconfigured with tools.

• Self-Hosted Agents: Custom-configured machines.

  Example

  xxxxxxxxxx
  2
  1
  pool:
  2
  vmImage: 'ubuntu-latest'
  

  • ubuntu-latest: A Microsoft-hosted agent running Ubuntu.

  • For a self-hosted agent:

    xxxxxxxxxx
    2
    1
    pool:
    2
    name: 'MySelfHostedPool'
    

6. Checkout

The checkout step determines the code repository and branch to be fetched for the pipeline.

Usage

• Checkout the repository containing the pipeline definition.

• Use custom repositories for additional resources.

  Example

  xxxxxxxxxx
  3
  1
  steps:
  2
  - checkout: self
  3
  clean: true
  

  • self: Refers to the pipeline’s main repository.

  • clean: true: Ensures a clean slate by deleting untracked files.

7. Steps

Steps are the smallest executable units in a pipeline. They define specific tasks or commands.

Types

1. Script Steps: Run shell or PowerShell commands.

2. Task Steps: Use predefined tasks (e.g., build, test, deploy).

3. Manual/Approval Steps: Require manual intervention (in deployment pipelines).

   Example: Script Step

   xxxxxxxxxx
   3
   1
   steps:
   2
   - script: echo "Building the project..."
   3
   displayName: 'Run Build Command'
   

   Example: Task Step

   xxxxxxxxxx
   5
   1
   steps:
   2
   - task: UseDotNet@2
   3
   inputs:
   4
      packageType: 'sdk'
   5
      version: '6.x'
   

Putting It All Together

Here’s a complete YAML pipeline example for a .NET project:

xxxxxxxxxx
23
1
name: 'MyPipeline-$(Build.BuildId)'
2
trigger:
3
- main
4
variables:
5
  buildConfiguration: 'Release'
6
jobs:
7
- job: BuildJob
8
  displayName: 'Build and Test'
9
  pool:
10
    vmImage: 'windows-latest'
11
  steps:
12
   - checkout: self
13
    clean: true
14
   - task: UseDotNet@2
15
    inputs:
16
      packageType: 'sdk'
17
      version: '6.x'
18
   - script: dotnet restore
19
    displayName: 'Restore Dependencies'
20
   - script: dotnet build --configuration $(buildConfiguration)
21
    displayName: 'Build Solution'
22
   - script: dotnet test --configuration $(buildConfiguration) --collect:"Code Coverage"
23
    displayName: 'Run Tests'

Summary