Fedora wants Podman users to try conmon v3 from October 12 to 18. The announcement appeared on October 7, ahead of the Fedora Podman test week. Its request is fairly specific: use the new Rust-based monitor in workflows the developers’ automated tests might not cover.
What happens after Podman starts a container?
A container can outlive the Podman command that started it. That leaves work for its monitor: following the process, handling input and output, keeping logs and collecting the exit status. The OCI runtime, usually crun or runc, is the part that starts the container. Conmon has a different job.
Consider an interactive shell. Getting a prompt is only the beginning. You may resize the terminal, detach, attach again or run another command through podman exec. Those are useful comparisons because a monitor problem need not appear at startup. Fedora specifically asks testers to try these operations.
The implementation changes from C to Rust. Fedora also describes a common interface for logging backends. The authors point to memory-safety benefits from Rust, while still asking people to look for bugs. A new language is a reason to test this component, not a substitute for that testing.
Choose a disposable test environment
For the test host, Fedora lists two routes: Fedora 44 with Podman from updates-testing, or a fully updated Fedora 45/Rawhide installation. Neither requires risking a work machine. A virtual machine without important data is enough to exercise many of the terminal and logging cases.
The installer checks we covered in the Fedora 45 installer test-week report ended on October 2. This is a separate exercise. Passing an installation test says little about how a container handles a detached terminal or a stream of logs. The new week gives those runtime tasks their own attention.
Enable conmon v3 and confirm the path
- In the test system, run sudo dnf install conmon-v3. Wait for the installation to finish.
- Create the file /etc/containers/containers.conf.d/99-conmon-v3.conf. Put [engine] on one line and conmon_path = ["/usr/bin/conmon-v3"] on the next.
- Run podman info. Look for /usr/bin/conmon-v3 and version 3 in its output. Check sudo podman info as well if you use rootful containers. If the path is wrong, review any user configuration that could override the system file.
- Launch a new container. The change does not replace the monitor for containers you already have running.
Compare behavior you can reproduce
Use a shell image you know. Resize its terminal, detach, then attach again. Try podman exec in another session. For logging, include a long line and a line without a final newline. Quadlet users should try their service’s restart path. Note whether each case used rootless or rootful Podman and crun or runc.
Keep the example small when something fails. Record the command, container image and package versions, then collect relevant logs and podman info –debug. Someone else needs enough detail to reproduce it. Use the linked results page for successful cases too; an empty results table cannot tell the team which configurations worked.
Leave a way back
To undo this selection, remove the drop-in file. Newly started containers should then use the previous monitor configuration. Containers already running do not exchange their monitor in place. Check the path again before repeating a comparison; otherwise you may spend time testing the old monitor without realizing it.