RHEL 8 fs.may_detach_mounts error

[crayroot]

RHEL 8.3 kernel 4.18.0-240.22.1.el8_3.x86_64

Ansible role adds fs.may_detach_mounts=1 to /etc/sysctl.conf

The following error is seen when executing sysctl -p:

sysctl: cannot stat /proc/sys/fs/may_detach_mounts: No such file or directory

Various Google searches indicate the version of runc included with the version of containerd may be related.

[alexsuppanz]

Hi

I can verify your issue

[ansible@vm-rhel-8-01 ~]$ sysctl -p
sysctl: cannot stat /proc/sys/fs/may_detach_mounts: No such file or directory

This is the second issue wich seems to be related to the current version of containerd.io (see #121 ). What I can see is that some of the issues introduced in runc-rc92 are resolved in current versions. The current version of containerd is already using runc 1.0-rc95

https://github.com/containerd/containerd/blob/a0efc5479553cf441600962aaa08580cd436d916/script/setup/runc-version#L1

But I think this issue should be raised directly at Elastic, since even the official documentation for CentOS/RHEL 8 mentions to install an older version of containderd.io, but I experience the same issue

containerd.io.x86_64                          1.3.7-3.1.el8                             @docker-ce-stable

Regards,
Alex

[m-a-leclercq]

Hi,
I still have the same issue on RHEL 8.4.

However, fs.may_detach_mounts is no longer required / part of the installation steps.
Do we still need this or can we just remove it from the role?
I can create the PR If needed.

Edit! From my understanding, sysctl -p not being able to stat may_detach_mounts just means the kernel does not have that option at all. If the option does not exist it should not be a problem?

[m-a-leclercq]

I found this source stating the following :

Newer kernels do not have this behavior and the mount goes away automatically.

I have verified that the behavior is also correct on RHEL 8 beta (4.18.0-32.el8.x86_64).

I believe RHEL8 does not need this flag at all and it can be safely removed for 4.18 Kernels.