Is it possible to set an VSTS Build variable in a Build Step so that the value can be used in a subsequent Build Step?

Question

I'm currently using Build in Visual Studio Team Services (was Visual Studio Online), and would like to be able to set a Build Variable in a Build Step so that the new value can be used in a subsequent Build Step.

Obviously you can set it before the Build starts but I'm looking to late bind the variable during a subsequent Build Step.

Is this possible?

Answer 1

When inside of a script you can update a variable by emitting the following in your ps1

"##vso[task.setvariable variable=testvar;]testvalue"

You can then pass the variable into the next script using $(testvar)

Answer 2

This doc from the API talks about what ##vso commands you can use.

Don't forget to set system.debug to true. It seems there is a bug that muted stdout and thus, all ##vso are not working.

https://github.com/Microsoft/vso-agent-tasks/blob/master/docs/authoring/commands.md

Answer 3

You can create a powershell script an reference it as a build task. Then inside your powershell scripts add this:

"##vso[task.setvariable variable=key]value"

After that on all your tasks you can read the variable as $(key). If you want to protect your variable, use:

"##vso[task.setvariable variable=secretVar;issecret=true]value"

And then use it as $(secretVar) in your next tasks.

Answer 4

I found this link helpful: https://docs.microsoft.com/en-us/azure/devops/pipelines/scripts/logging-commands?view=azure-devops&tabs=powershell

This has the complete options of what you can do: https://docs.microsoft.com/en-us/azure/devops/pipelines/process/variables?view=azure-devops&tabs=yaml%2Cbatch

You can reuse set variable from task to task, and also job to job. I couldn't find anything on stage to stage.

In summary:

jobs:

# Set an output variable from job A
- job: A
  pool:
    vmImage: 'vs2017-win2016'
  steps:
  - powershell: echo "##vso[task.setvariable variable=myOutputVar;isOutput=true]this is the value"
    name: setvarStep
  - script: echo $(setvarStep.myOutputVar)
    name: echovar

# Map the variable into job B
- job: B
  dependsOn: A
  pool:
    vmImage: 'ubuntu-16.04'
  variables:
    myVarFromJobA: $[ dependencies.A.outputs['setvarStep.myOutputVar'] ]  # map in the variable
                                                                          # remember, expressions require single quotes
  steps:
  - script: echo $(myVarFromJobA)
    name: echovar