Execute or not template in Azure Pipeline with runtime condition

user_4717188 0
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I have got an Azure Pipeline already running. Now I want to execute a sequence of steps only if a certain condition becomes true during runtime.

Example

steps:
  - template: steps_checkout.yml
  # some more steps here

  - bash: |
    if [ some condition ]; then 
      echo "##vso[task.setVariable variable=rebuild_lib]false"
      echo "Did set rebuild_lib to false"
     fi

  - if eq( variables.rebuild_lib, true) ):
    - template: steps_lib_build.yml

The line if eq( variables.rebuild_lib, true) ) does not work, because it is not a correct condition syntax. I could use

${{ if eq( parameters.something, true ) }}

but that needs to be known at runtime. Accodring to https://docs.microsoft.com/en-us/azure/devops/pipelines/process/expressions?view=azure-devops an expression can also be $[ if eq(variables.rebuild_lib), true] to be evaluated at runtime, but using this, I get

Unexpected value '$[ if eq( variables.rebuild_lib, true) ) ]'

Seems like the yml cannot be modified at runtime this way.

So how do I decide to use a template at runtime?

I could imagine giving the variable as parameter to the next template adapter.yml. This template adapter.yml gets then the variable as parameter and could use the ${{}} expression and again use the next template steps_lib_build.yml ... but creating templates only for that seems somehow ... workaroundish.

Also using something like

- template: steps_lib_build.yml
  condition: ...

does not work.

Is there a good way to do this?

azure-pipelines-yaml azure-pipelines
1 Answers

In your current yaml, you are trying to use the Parameters to select a template. But according the doc: Parameters to select a template at runtime, this is only used at runtime. So here, we can use the job conditions and output variables to help us separate the second the yaml temp.

Here is a demo yaml example to help you:

trigger: none

pool:
  vmImage: ubuntu-latest

jobs:
  - job: A
    steps:
    - task: Bash@3
      name: ProduceVar  # because we're going to depend on it, we need to name the step
      inputs:
        targetType: 'inline'
        script: 'echo "##vso[task.setVariable variable=rebuild_lib;isOutput=true]false"'
  - job: B
    condition: and(succeeded(), eq(dependencies.A.outputs['ProduceVar.rebuild_lib'], 'true'))
    dependsOn: A
    steps:
      # - script: echo Hello B
      - template: start.yaml

Please Note: We should use the task Bash to help us set the output variable, because we're going to depend on the task name.

user_153050380
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