Can Conditional Variable Assignment be Done in Azure Pipelines?

Question

Azure Pipelines has Expressions and Conditions, but I can find no way to assign one of two values to a variable, based on a condition.

Is there any way to accomplish what this pseudo-code would?

    ${{ if endsWith( variables['Build.SourceBranchName'], '/master' ) }}: 
      buildVersion: variables['mavenVersion']
    ${{ else }}: 
      buildVersion: variables['Build.SourceBranchName']

Answer 1

I was closer than I thought. This is not pretty, but it worked. (with more yaml context)

variables:
  ${{ if eq( variables['Build.SourceBranchName'], 'master' ) }}: 
    buildVersion: ${{ variables['mavenVersion'] }}
  ${{ if ne( variables['Build.SourceBranchName'], 'master' ) }}: 
    buildVersion: ${{ variables['Build.SourceBranchName'] }}

  buildKey: ${{ format('{0}_{1}', variables['supportReleaseNumber'], variables['buildVersion']) }}
  buildNum: $[counter(variables['buildKey'], 1)]  # same as $(Rev:r), but more widely usable 

name: $(buildKey)_$(buildNum)  # build run name

Answer 2

As an extension to @Mike Murray's answer, if you are using variable groups you must define additional variables as name value pairs. To use conditional variable assignment in this case would be as follows:

variables:
- group: 'my-variable-group'
- name: myfirstadditionalvariable
  value: 100
- name: myconditionalvariable
  ${{ if eq( variables['Build.SourceBranchName'], 'master' ) }}: 
    value: masterBranchValue
  ${{ if ne( variables['Build.SourceBranchName'], 'master' ) }}: 
    value: featureBranchValue

Answer 3

This should do the trick....

BuildVersion is initialised as $(Build.SourceBranch) if it's the master branch you change that to the $(mavenVersion) else no change.

variables:
  mavenVersion: '1.0'
  buildVersion: $(Build.SourceBranch)

pool:
  vmImage: 'ubuntu-latest'

steps:

- script: echo '##vso[task.setvariable variable=buildVersion]$(mavenVersion)'
  displayName: "Set the buildVersion as mavenVersion if the Build.SourceBranch = 'refs/heads/master' "
  condition: eq(variables['Build.SourceBranch'], 'refs/heads/master')

- script: echo $(buildVersion)
  displayName: 'Printing the variable'

non-master branches prints 'refs/heads/branch_name' which is mavenVersion

master branch prints 1.0 which is mavenVersion

Answer 4

@Mike Murray, thank you for this! I have been trying to solve this for ages. When builds are triggered from pull requests the SourceBranchName is always 'merge'. Your answer helped me come up with this solution for getting the target branch name for both scenarios, manual builds and builds triggered by pull-requests:

${{ if ne( variables['Build.SourceBranchName'], 'merge' ) }}: 
    environment: ${{ variables['Build.SourceBranchName'] }}
  ${{ if endsWith( variables['System.PullRequest.TargetBranch'], 'dev' ) }}: 
    environment: dev
  ${{ if endsWith( variables['System.PullRequest.TargetBranch'], 'staging' ) }}: 
    environment: staging
  ${{ if endsWith( variables['System.PullRequest.TargetBranch'], 'master' ) }}: 
    environment: prod

Not very pretty, but finally works.

Answer 5

With this update your YAML is valid:

    ${{ if endsWith( variables['Build.SourceBranchName'], '/master' ) }}: 
      buildVersion: variables['mavenVersion']
    ${{ else }}: 
      buildVersion: variables['Build.SourceBranchName']