Variables in Azure DevOps Pipelines

• Azure DevOps Pipeline has variables, we can assign values to be used within pipeline across stages, jobs or steps.
• Variables values can be changed during the pipeline execution
• Pipeline execution has 3 phases
  • Queue time phase
  • Compile phase
  • Runtime phase
• Variables can be used by 3 different expressions Refer Here
  • macro $(var)
  • template ${{ variables.var }}
  • runtime expression $[variables.var]
• Syntax to be used in pipelines Refer Here
• Script variables can be set from scripts "##vso[task.setvariable variable=myVar;]foo"
• Variables can be created at
  • pipeline level
  • stages level
  • jobs level
• Try this pipeline

---
trigger:
  - main

pool: 
  vmImage: ubuntu-22.04

variables:
  - name: var1
    value: value1

stages:
  - stage: stage1
    displayName: 'Stage 1'
    variables:
      - name: var2
        value: value2
    jobs:
      - job: job1
        displayName: Job 1
        variables:
          - name: var3
            value: value3
        steps:
          - bash: echo "##vso[task.setvariable variable=var1;]newvalue"
          - script: "echo $(var1)"
          - script: "echo $(var2)"
          - script: "echo $(var3)"

• I have 10 variables and i want to use them in multiple pipelines these values can be secrets or text values, in these kind of cases we use variable groups. To create a variable group
• Lets create a variable group
  
  
• Now look at below pipeline

---
trigger:
  - main

pool: 
  vmImage: ubuntu-22.04

variables:
  - name: var1
    value: value1
  - group: group1

stages:
  - stage: stage1
    displayName: 'Stage 1'
    variables:
      - name: var2
        value: value2
    jobs:
      - job: job1
        displayName: Job 1
        variables:
          - name: var3
            value: value3
        steps:
          - bash: echo "##vso[task.setvariable variable=var1;]newvalue"
          - script: "echo $(var1)"
          - script: "echo $(var2)"
          - script: "echo $(var3)"
          - script: "echo java_version $(java_version) password = $(password)"
            displayName: "Displaying values from group"

Lets try writing a pipeline for the following

• The application which we need to work
• manual steps

git clone https://github.com/DevProjectsForDevOps/StudentCoursesRestAPI.git
cd StudentCoursesRestAPI
docker image build -t shaikkhajaibrahim/studentcoursescd:(Build-ID) .
docker image push shaikkhajaibrahim/studentcoursescd:(Build-ID)

• Azure DevOps when it needs to connect to something external uses Service Connections.
• Lets create a service connection to docker hub
  • Navigate to Project Settings => Service Connections => New service connection and follow the screenshots below
    
    
    
    
• We have created a pipeline with following content

---

trigger:
  - master

pool: 
  vmImage: ubuntu-22.04

steps:
  - task: Docker@2
    displayName: build and push docker image
    inputs:
      containerRegistry: 'DockerHubConnection'
      command: buildAndPush
      repository: 'shaikkhajaibrahim/studentcoursescd'
      tags: '$(Build.BuildId)'

• Run the pipeline
  
  

Azure DevOps Extensions

• Azure DevOPs Extensions provide extra set of tasks to Azure Pipelines. Refer Here
• Refer Here for notifications on teams channel
• Examples from Microsoft Refer Here