Azure Devops build variables not updating during build

Question

I have the following variable:

Name: TestVar

Value: xxx

And the following script:

$testVar=$env:TestVar.ToLower()

if($testVar-eq 'xxx'){

$testVar= 'updated'

Write-Host "##vso[task.setvariable variable=TestVar;]$testVar"

The value after a run remains xxx instead of updated .

Answer 1

The syntax of "##vso[task.setvariable variable=TestVar;]$testVar" is to update the variable value only for this build running, not for future builds.

If you want to update the build variable list you need to update the build definition with Rest API .

An example of a PowerShell script that does it:

$head = @{Authorization = "Bearer $env:SYSTEM_ACCESSTOKEN" }
$url="$(System.TeamFoundationCollectionUri)$(System.TeamProject)/_apis/build/definitions/$(System.DefinitionId)?api-version=5.0"         
$build = Invoke-RestMethod -Uri $url -Method Get -Headers $head -ContentType application/json
$build.variables.TestVar.value = "updated"
$json = $build  | ConvertTo-Json -Depth 10
Invoke-RestMethod -Uri $url -Method Put -Headers $head -Body $json -ContentType application/json

Answer 2

If you want to make the change permanent you need to do it via the api as follows, otherwise its just for the duration of the run

$projecturi = "$env:SYSTEM_TEAMFOUNDATIONCOLLECTIONURI"
$project = "$env:SYSTEM_TEAMPROJECT"
$accessToken = $env:SYSTEM_ACCESSTOKEN
$buildID = "$env:BUILD_BUILDID"

$headers = @{ "Authorization" = "Bearer $accessToken" }

$buildurl= $projecturi + $project + "/_apis/build/builds/" + $buildID + "?api-version=2.0"

Write-Host $buildurl

$getbuild = Invoke-RestMethod -Uri $buildurl -headers $headers -Method Get |select definition

Write-Host $getbuild

$definitionid = $getbuild.definition.id

Write-Host $definitionid

$defurl = $projecturi + $project + "/_apis/build/definitions/" + $definitionid + "?api-version=2.0"

$definition = (Invoke-WebRequest $defurl -Headers $headers -Method GET -ContentType "application/json" -UseBasicParsing).Content | ConvertFrom-Json

$definition.variables.testvar.value = "Updated"

$json = @($definition) | ConvertTo-Json  -Depth 100


Try{
  $result = (Invoke-WebRequest $defurl -Method "Put" -Headers $headers -ContentType "application/json" -Body $json -UseBasicParsing).Content | ConvertFrom-Json
}
Catch{
  $errorMessage = $_.Exception.Message
  $errorDetail = $_
  $message = @"
$errorMessage
$errorDetail
"@

  Write-Error $message -ErrorAction Continue
  return 0
}