Microsoft.TeamFoundation.Build.WebApi Get Build Status Launched by PR policy - azure

Question

In our pipeline we programmatically create a pull request (PR). The branch being merged into has a policy on it that launches a build. This build takes a variable amount of time. I need to query the build status until it is complete (or long timeout) so that I can complete the PR, and clean up the temp branch.
I am trying to figure out how to get the build that was kicked off by the PR so that I can inspect the status by using Microsoft.TeamFoundation.Build.WebApi, but all overloads of BuildHttpClientBase.GetBuildAsync require a build Id which I don't have. I would like to avoid using the Azure Build REST API. Does anyone know how I might get the Build kicked off by the PR without the build ID using BuildHttpClientBase?
Unfortunately the documentation doesn't offer a lot of detail about functionality.

Answer 1

Answering the question you asked:
Finding a call that provides the single deterministic build id for a pull request doesn't seem to be very readily available.
As mentioned, you can use BuldHttpClient.GetBuildsAsync() to filter builds based on branch, repository, requesting user and reason.
Adding the BuildReason.PullRequest value in the request is probably redundant according to the branch you will need to pass.
var pr = new GitPullRequest(); // the PR you've received after creation
var requestedFor = pr.CreatedBy.DisplayName;
var repo = pr.Repository.Id.ToString();
var branch = $"refs/pull/{pr.PullRequestId}/merge";
var reason = BuildReason.PullRequest;
var buildClient = c.GetClient<BuildHttpClient>();
var blds = await buildClient.GetBuildsAsync("myProject",
branchName: branch,
repositoryId: repo,
requestedFor: requestedFor,
reasonFilter: reason,
repositoryType: "TfsGit");
In your question you mentioned wanting the build (singular) for the pull request, which implies that you only have one build definition acting as the policy gate. This method can return multiple Builds based on the policy configurations on your target branch. However, if that were your setup, it would seem logical that your question would then be asking for all those related builds for which you would wait to complete the PR.
I was looking into Policy Evaluations to see if there was a more straight forward way to get the id of the build being run via policy, but I haven't been able to format the request properly as per:
Evaluations are retrieved using an artifact ID which uniquely identifies the pull request. To generate an artifact ID for a pull request, use this template:
vstfs:///CodeReview/CodeReviewId/{projectId}/{pullRequestId}
Even using the value that is returned in the artifactId field on the PR using the GetById method results in a Doesn't exist or Don't have access response, so if someone else knows how to use this method and if it gives exact build ids being evaluated for the policy configurations, I'd be glad to hear it.
An alternative to get what you actually desire
It sounds like the only use you have for the branch policy is to run a "gate build" before completing the merge.
Why not create the PR with autocomplete.
Name - autoCompleteSetBy
Type - IdentityRef
Description - If set, auto-complete is enabled for this pull request and this is the identity that enabled it.
var me = new IdentityRef(); // you obviously need to populate this with real values
var prClient = connection.GetClient<GitHttpClient>();
await prClient.CreatePullRequestAsync(new GitPullRequest()
{
CreatedBy = me,
AutoCompleteSetBy = me,
Commits = new GitCommitRef[0],
SourceRefName = "feature/myFeature",
TargetRefName = "master",
Title = "Some good title for my PR"
},
"myBestRepository",
true);