I’m not sure exactly what you mean by “name or id of the pull request” and I don’t think there’s a pipeline variable that represents that. You can check the variable references here: https://docs.microsoft.com/en-us/azure/devops/pipelines/build/variables?view=azure-devops&tabs=yaml#build-variables

But you could for example use the

Build.SourceVersion

variable which represents the Git commit ID.

So you could do something like this in your YAML:

- task: Pulumi@1
    inputs:
      ...
    env:
      COMMIT_ID: $(Build.SourceVersion)

And then in your Pulumi program, just read the environment variable

COMMIT_ID

and concatenate that to your resource names.