Specify source channel for asset validation

[garath]

Resolves dotnet/dnceng#1964.

The validation checks get confused if an asset with the same name and version is published more than once. This is rare, but can happen. This change adds the source-channel flag where appropriate for calls to darc.

[garath]

I'm not sure how to test this. The code is all mixed in with actual asset promotion, so it's not really safe to make "simple" cuts to the pipeline. I could add a whole "dry-run" flag that does everything except the permanent changes, but that seems like more work than worth. Though I'll certainly consider reviewer pushback if folks disagree.

[riarenas]

I believe disabling this job: https://github.com/dotnet/arcade-validation/blob/main/azure-pipelines.yml#L299-L321 would let you run a validation build without the build being promoted.

EDIT: Or the entire stage 😛

[garath]

I believe disabling this job

The test-publishing script in the Validate_Publishing job also makes Actual Changes in a few spots like these:

arcade-validation/eng/validation/test-publishing.ps1

Line 69 in a2dc021

Git-Command $global:azdoRepoName push origin HEAD

arcade-validation/eng/validation/test-publishing.ps1

Line 80 in a2dc021

& $darc add-build-to-channel --id $global:buildId --channel $global:targetChannel --source-branch $global:targetBranch --github-pat $global:githubPAT --azdev-pat $global:azdoToken --password $global:barToken --publishing-infra-version 3

[missymessa]

LGTM

[riarenas]

I believe disabling this job

The test-publishing script in the Validate_Publishing job also makes Actual Changes in a few spots like these:

arcade-validation/eng/validation/test-publishing.ps1

Line 69 in a2dc021

Git-Command $global:azdoRepoName push origin HEAD

arcade-validation/eng/validation/test-publishing.ps1

Line 80 in a2dc021

& $darc add-build-to-channel --id $global:buildId --channel $global:targetChannel --source-branch $global:targetBranch --github-pat $global:githubPAT --azdev-pat $global:azdoToken --password $global:barToken --publishing-infra-version 3

These are fine. They just cause the arcade-validation build to get put in the general testing channel, and it pushes a branch to the internal repo that gets cleaned up when everything works.

I'm also pretty OK with you checking this in and fixing afterwards if something is off.