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MongoDB integration tests fail on newer GitHub Actions runner kernels

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#626 2 comments 0 reactions 0 assignees View on GitHub

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@nmummau is already working on this.

Since Oct 20, 2026.

  • #625 by @nmummau — open

Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
74/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
csharp, docker, github-actions
Domain
ci-cd, testing

Research direction

Read .github/workflows/tests.yml and find the Mongo integration job that runs Eventuous.Tests.Projections.MongoDB.csproj; check how its runner is selected and how the other suites select theirs. Update the Mongo suite runner as described in the issue and document the upstream compatibility issue beside the override. Done when the Mongo suite passes on GitHub Actions and the other suites retain their runner selection.

Written by the indexing model from the issue text.

Description

Describe the bug

The Tests / Build and test mongo job fails while starting its MongoDB container. MongoDB exits with code 1 because its startup check rejects the runner's Linux kernel, preventing the projection tests from executing.

Observed in this failing GitHub Actions job on October 19, 2026

To reproduce

  1. Run the Mongo integration suite through .github/workflows/tests.yml on an ubuntu-latest runner with an affected kernel.

  2. The workflow executes:

    dotnet test src/Mongo/test/Eventuous.Tests.Projections.MongoDB/Eventuous.Tests.Projections.MongoDB.csproj -c "Debug CI" -f net10.0

  3. The integration fixture starts the mongo:8 image through Testcontainers.

  4. MongoDB rejects the kernel during startup, and fixture initialization fails.

Reproduction depends on the runner assigned to the job and the image resolved by the floating mongo:8 tag.

Expected behavior

The MongoDB container starts successfully, and the Mongo projection integration suite runs and passes in CI.

Actual behavior

The job reports the following failure for ShouldProjectImported (container ID and repeated stack trace omitted):

failed ShouldProjectImported(MongoProjectionOptions { CollectionName = test }) (0ms)
[Test Failure] ContainerNotRunningException: Container ... exited with code 1.

MongoDB cannot start: Linux kernel versions 6.19 and newer has a known incompatibility with this version of MongoDB. See https://jira.mongodb.org/browse/SERVER-121912 for more information.

Environment

  • Workflow: .github/workflows/tests.yml, called by the PR and preview workflows.
  • Runner label: ubuntu-latest.
  • Test target: net10.0, x64, Debug CI configuration.
  • Container image configured by the fixture: mongo:8.
  • The failure excerpt does not identify the exact host kernel release or resolved MongoDB patch version.

Additional context

GitHub began migrating ubuntu-latest to Ubuntu 26.04 on October 19, 2026. The timing is consistent with a runner change exposing the MongoDB compatibility problem, although the excerpt alone does not establish which runner image was assigned.

MongoDB tracks the underlying kernel incompatibility in SERVER-121912. It also tracks a startup-check issue that rejects Ubuntu kernels containing the upstream fix in SERVER-136848. Docker containers share the host kernel, so changing only the container's base distribution does not address the host-kernel check.

Proposed workaround

Pin only the Mongo integration suite to ubuntu-24.04, retaining ubuntu-latest for the other suites. GitHub's Ubuntu 24.04 runner manifest lists kernel 6.17.0-1022-azure for image 20261012.334.1, below MongoDB's affected range.

Document the upstream issue beside the runner override so the workaround can be revisited when a compatible MongoDB image is available. The runner label does not permanently pin a kernel version.

A local workflow change passes Actionlint and git diff --check; confirmation in GitHub Actions is still pending.

Acceptance criteria

  • The Mongo integration suite passes on GitHub Actions with the selected runner.
  • Other integration suites retain their existing runner selection.
  • The runner override documents the upstream compatibility issue.
Dominant language
C#
Stars
512
Forks
99
Avg merge
5d 6h
Merged PRs (30d)
5

Getting set up

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

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