How can we run multiple test containers that use mongodb at the same time?

[PatrickGhosn]

Currently, if more than one of our pipelines run on the same machine, they will run into the issue of both trying to use port 27017 to run a mongodb container for the integration tests. Is there a way to get around that limitation and be able to run two or more instances of the same integration tests at the same time? Perhaps by being able to dynamically assign the container port through a shell variable.

[HofmeisterAn]

Is there a way to get around that limitation and be able to run two or more instances of the same integration tests at the same time?

Yes, Testcontainers maps the container port (in your case 27017) automatic to a random host port. This allows running multiple instances at the same time. It is the default behaviour.

I assume you bind a fix host port. Can you share your configuration?

[HofmeisterAn]

You are using a private registry, right? Does it contain or proxy the resource reaper image?

[PatrickGhosn]

The mongo and reaper images are the default ones, so I think from the public docker registiry. And there are no proxies, outgoing access is direct.

I saw the following suggested to be added in another thread:

            await ResourceReaper.GetAndStartDefaultAsync()
                .ConfigureAwait(false);

Do you think it might resolve the issue?

[HofmeisterAn]

Do you think it might resolve the issue?

No. I would not recommend it as a final solution. Does it happens frequently? Can you start the default resource reaper standalone? Is Testcontainers able to initialize it?

[PatrickGhosn]

It happens around 1-2 times every 5 runs. Usually restarting the pipeline after a fail has it run normally. Usually it happens if there's another pipeline running and is using up the CPU.

Is it possible to keep a resource reaper running constantly on the machine?

[HofmeisterAn]

Oh wow, that is way too much and very unusual. If the issue relates to the load, try following:

var resourceReaperSessionId = Guid.NewGuid();

_ = await ResourceReaper.GetAndStartNewAsync(resourceReaperSessionId, initTimeout: TimeSpan.FromMinutes(5))
  .ConfigureAwait(false);

_ = new TestcontainersBuilder<TestcontainersContainer>()
  .WithResourceReaperSessionId(resourceReaperSessionId)
  .WithImage(...)
  .Build();

Make sure you run GetAndStartNewAsync only once and use the session id everywhere.

Is it possible to keep a resource reaper running constantly on the machine?

No