How to update Azure build definition agent from vs2017-win2016 to windows-2019 programmatically

Question

I am trying to programatically update all my build pipeline agents from vs2017-win2016 to windows-2019. I have access to AZ CLI, PowerShell and REST API but I haven't found the magic incantation to make it work. Specifically I would like to update the Azure Pipeline agent for a specific project and build definition name.

Answer 1

How to update Azure build definition agent from vs2017-win2016 to windows-2019 programmatically

We could use the REST API Definitions - Get to get all the info about this definition in the body, then we could update the body and use the Definitions - Update to update the value of the release definition variable from a build pipeline:

PUT https://dev.azure.com/{organization}/{project}/_apis/build/definitions/{definitionId}?api-version=5.0

Following is my test inline powershell scripts:

$url = "https://dev.azure.com/{organization}/{project}/_apis/build/definitions/57?api-version=5.0"

Write-Host "URL: $url"
$pipeline = Invoke-RestMethod -Uri $url -Headers @{
    Authorization = "Bearer $env:SYSTEM_ACCESSTOKEN"
}
Write-Host "Pipeline = $($pipeline | ConvertTo-Json -Depth 100)"

# Update an existing build definition named and build definition agent to its new value 2
$pipeline.process.target.agentSpecification.identifier= "windows-2019"
$pipeline.name= "UpdateVariabletest"

####****************** update the modified object **************************
$json = @($pipeline) | ConvertTo-Json -Depth 99


$updatedef = Invoke-RestMethod -Uri $url -Method Put -Body $json -ContentType "application/json" -Headers @{Authorization = "Bearer $env:SYSTEM_ACCESSTOKEN"}

write-host "==========================================================" 
Write-host "The value of build definition named and build definition agent is updated to" 

$updatedef.process.target.agentSpecification.identifier
$updatedef.name

You could check the similar thread for some more details.