Needs extension for Centos/RHEL distros

[rsohn]

The use of a file such as /var/run/reboot-required is specific to Ubuntu family distros, but such a flag does not get set for RHEL/Centos distros using Yum/RPM for package management. In those environments, the yum-utils package is installed, then the needs-restarting -r command can run to detect the need for a reboot when its exit code is 1.

Suggest adding an optional argument to kured that provides a command to be executed, If the command exists and the exit code from that command is non-zero, then trigger a reboot the same as if the sentinel file exists. The default value for the option, if provided, would be needs-restarting -r.

Reference: How can I check from the command line if a reboot is required on rhel or centos

An alternative approach would be include a short script along the lines of the following that runs when installed on a RHEL/Centos system:

[[ -x /bin/needs-restarting ]] && needs-restarting -r >/dev/null || touch /var/run/reboot-required

[awh]

Thanks for the report @rsohn. I like your idea of specifying a command, but sadly kured is running inside a container - it has neither access to arbitrary executables in the host filesystem, nor the sources of information such an executable might be using to determine if a reboot is required. You'll note that for the Debian/Ubuntu case the daemonset bind mounts /var/run into the container so that it can detect the presence of the sentinel file in the host - we would have to do something similar here after working out where needs-restarting is getting its information from. We may also have to include a copy of needs-restarting in the kured container image. In the meantime your workaround is sound, I will update the docs until we can do better.

[Matty9191]

@rsohn I cobbled together a restart script for my Fedora and CentOS lab systems. I'm installing and activating it with ansible and its working like a champ. Not sure if this will be of any value to you but thought I would pass it on.

[awh]

Some progress on this - #39 moves us towards supporting CentOS/RHEL without external scripts...

[davidkarlsen]

With #39 on board - what more is needed?

[rsohn]

It appears to me to be complete.

[davidkarlsen]

So . basically this issue should be closed as fixed?

[etiennetremel]

Maybe I'm missing something but if I look at the changes introduced by #39, it doesn't let you execute a binary.
@awh, should we introduce a new flag for this purpose? I can help if needed

[lumi017]

Some progress on this - #39 moves us towards supporting CentOS/RHEL without external scripts...

@awh can you please elaborate? We still cannot use needs-restarting -r as sentinel.
The current implementation is using sentinelCmd := newCommand("/usr/bin/nsenter", "-m/proc/1/ns/mnt", "--", "/usr/bin/test", "-f", rebootSentinel)

Some tests to confirm it doesn't work with a command:

[root@host ~]# needs-restarting -r
No core libraries or services have been updated.
Reboot is probably not necessary.
[root@host ~]# echo $?
0
[root@host ~]# test -f 'needs-restarting -r'
[root@host ~]# echo $?
1
[root@host ~]# test -f '! needs-restarting -r'
[root@host ~]# echo $?
1

[root@host ~]# needs-restarting -r
Core libraries or services have been updated:
  systemd -> 219-62.el7_6.6

Reboot is required to ensure that your system benefits from these updates.

More information:
https://access.redhat.com/solutions/27943
[root@host ~]# echo $?
1
[root@host ~]# test -f '! needs-restarting -r'
[root@host ~]# echo $?
1
[root@host ~]# test -f 'needs-restarting -r'
[root@host ~]# echo $?
1

Can we have a successful implementation to depend on a return code of needs-restarting -r or you cannot bypass some limitation(s)?

[rsohn]

It seems like "test" might not be the right mechanism to use here. Certainly, the -f option is a problem, as that checks for the existence of a file, rather than a return code.

Perhaps eval 'needs-restarting -r >/dev/null' is closer to what is needed here?

[winjer]

PR #77 Seems to work ok and it would be great if someone is able to review it and merge it. Is that possible? @awh?

[github-actions]

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