[Bug]: When stopping a Linux container in a unit test (running in Azure Pipeline), I get exception

[StefH]

Testcontainers version

4.5.0

Using the latest Testcontainers version?

Yes

Host OS

Linux

Host arch

x86

.NET version

8

Docker version

-

Docker info

-

What happened?

System.NullReferenceException : Object reference not set to an instance of an object.

Relevant log output

Failed WireMock.Net.Tests.Testcontainers.TestcontainersTests.WireMockContainer_Build_WithImageAsText_And_StartAsync_and_StopAsync [9 s]
   Error Message:
    System.NullReferenceException : Object reference not set to an instance of an object.
   Stack Trace:
      at DotNet.Testcontainers.Containers.DockerContainer.UnsafeStopAsync(CancellationToken ct) in /_/src/Testcontainers/Containers/DockerContainer.cs:line 567
    at DotNet.Testcontainers.Containers.DockerContainer.StopAsync(CancellationToken ct) in /_/src/Testcontainers/Containers/DockerContainer.cs:line 319

Additional information

• Fix TestcontainersTests to ignore exception when stopping wiremock/WireMock.Net#1314
• Bump Testcontainers version to 4.5.0 wiremock/WireMock.Net#1311

[HofmeisterAn]

Relates to: #1458.

[HofmeisterAn]

Or did I misunderstand the issue? Is WireMock already on version 4.5.0?

Edit: I haven't looked closely at the issue, but I saw that the tests are using WithAutoRemove(true). Please note that this removes the container when the entry process exits (the container runtime engine removes it). In that case, receiving a null pointer is expected.

[StefH]

Or did I misunderstand the issue? Is WireMock already on version 4.5.0?

Edit: I haven't looked closely at the issue, but I saw that the tests are using WithAutoRemove(true). Please note that this removes the container when the entry process exits (the container runtime engine removes it). In that case, receiving a null pointer is expected.

• WireMock.Net has just moved to 4.5.0
• Thanks for the heads-up for WithAutoRemove(true), in that case I do not need to stop it manually anymore. (Which was required for the older Testcontainers version)

[StefH]

@HofmeisterAn
Although, I was wondering if the StopAsync should be more robust to handle this scenario?

[HofmeisterAn]

Just to avoid any confusion and make it easier to understand how TC works:

• WithAutoRemove(bool) tells the container runtime to automatically remove the container when its entry process exits. It's usually not needed and not recommended unless you're doing something like one-shot setups.
• WithCleanUp(bool) sets up Ryuk (the resource reaper), which is a separate container that watches your resources and cleans them up after the test session (even when the test host crash). This is the recommended and default approach.

[...] I do not need to stop it manually anymore.

Ideally, you should let Ryuk handle the cleanup.

Although, I was wondering if the StopAsync should be more robust to handle this scenario?

I'm not totally sure about this, but with WithAutoRemove(true), the container runtime deletes the container in the background. TC isn't aware of it and can't manage it properly.

Hope that helps.