[jira] [Commented] (MESOS-6541) Mesos test should mount cgroups_root

["Jason Lai (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MESOS-6541?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15634334#comment-15634334 ] 

Jason Lai commented on MESOS-6541:
----------------------------------

It would be good to call `unshare(2)` with `CLONE_NEWNS` to fork a new mount namespace for the test suite process. In this case, you can do whatever you want with the process' mount table without affecting other processes' view of their root FS.

However, during the test runs, it is important to make sure that minimum changes are made to cgroup hierarchies or the changes should be idempotent, since such changes do have side effects across mount namespaces.

> Mesos test should mount cgroups_root
> ------------------------------------
>
>                 Key: MESOS-6541
>                 URL: https://issues.apache.org/jira/browse/MESOS-6541
>             Project: Mesos
>          Issue Type: Bug
>          Components: cgroups, test
>            Reporter: Yan Xu
>
> Currently on hosts without prior cgroups setup and sysfs is mounted at /sys, mesos tests would fail like this:
> {noformat:title=}
> [ RUN      ] HTTPCommandExecutorTest.TerminateWithACK
> F1103 19:54:40.807538 439804 command_executor_tests.cpp:236] CHECK_SOME(_containerizer): Failed to create launcher: Failed to create Linux launcher: Failed to mount cgroups hierarchy at '/sys/fs/cgroup/fr
> eezer': Failed to create directory '/sys/fs/cgroup/freezer': No such file or directory
> {noformat}
> This is because the agent chooses to use {{LinuxLauncher}} based on availability of the {{freezer}} subsystem alone. However for it to work, one needs to do the following
> {noformat:title=}
> mount -t tmpfs cgroup_root /sys/fs/cgroup
> {noformat}
> in order to make  {{/sys/fs/cgroup}} writable. 
> I have always run the command manually in the past when this failure happens but this could be baffling especially to new developers. Mesos tests should just mount it if it's not already done.



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