Re: [pve-devel] [PATCH v3 ceph master, ceph quincy-stable 8, pve-storage, pve-manager 00/13] Fix #4759: Configure Permissions for ceph-crash.service

[Max Carrara <m.carrara@proxmox.com>]

On 2/23/24 17:19, Friedrich Weber wrote:
> On 21/02/2024 14:15, Max Carrara wrote:
>> On 2/21/24 12:55, Friedrich Weber wrote:
>>> [...]
>>>
>>> - the `ceph-crash` service does not restart after installing the patched
>>> ceph-base package, so the reordering done by patches 02+04 does not take
>>> effect immediately: ceph-crash posts crash logs just fine, but logs to
>>> the journal that it can't find a keyring. After a restart of ceph-crash,
>>> the patch takes effect, so only a tiny inconvenience, but still: Not
>>> sure if restarting the service is something we'd want to do in a
>>> postinst -- is this an acceptable thing to do in a postinst?
>>
>> Initially the service was being restarted, but that's omitted in the new
>> hook, as Fabian and I had noticed that `ceph-crash` just checks for its
>> expected keys after its waiting period again anyways. I had unfortunately
>> forgotten to put that into the changelog of the postinst hook stuff -
>> mea culpa>
>> I think restarting the service would be necessary then in order to apply
>> the new sequence which keys are checked in, as that's hard-coded in
>> `ceph-crash`.
>>
>> It certainly should be acceptable (as we already do it in some instances),
>> as long as we restart it only if the service is enabled. That was part
>> of the old BASH function anyway - I don't think there's any harm in adding
>> it back (either in BASH or Perl).
> 
> If it's acceptable, I think it would be nice to restart ceph-crash (it
> doesn't seem to be restarted that often).

I agree!

> 
>>> - Might there be issues in a mixed-version cluster scenario, so if some
>>> node A already has an updated pve-storage package (patches 05-10), but
>>> node B doesn't yet? One thing I noticed is that node A will add the
>>> [client.crash] section, but node B may remove it again when it needs to
>>> rewrite the Ceph config (e.g. when creating a monitor). I don't find
>>> this particular issue too concerning, as hopefully node B will be
>>> updated eventually as well and reinstate the [client.crash] section. But
>>> I wonder if there could be other more serious issues?
>>
>> The scenario you mentioned might indeed happen somehow, but once all
>> nodes are updated - even if the config has been changed inbetween updates -
>> the '[client.crash]' section should definitely exist.
>>
>> One issue that's been fixed by moving things to the Perl helper is that
>> simultaneous updates could potentially modify 'ceph.conf' at the same time
>> - the Perl helper now locks the file on pmxcfs, so that cannot happen anymore.
> 
> Nice!
> 
>> I cannot think of any other scenario at the moment.
> 
> Yeah, me neither.
> 
>> In any case, even if *somehow* 'ceph.conf' ends up not containing the section
>> or the keyring file ends up missing, the helper script will be available
>> after the update has been performed, so it's possible to just run it again
>> manually to adapt the config.
>>
>> That being said, this reminds me that the '[ceph.crash]' section, the location
>> of the keyring file, etc. should probably be in our docs as well, so I will
>> send in a follow-up series for that (unless this series ends up needing a v4,
>> then I'll include it there).
>>
>> Thanks again for the feedback and the tests you ran!
> 
> Sure! I ran some more tests installing a fresh Reef cluster with the
> patched packages, and did not notice any major issues.
> 
> One minor thing I noticed: If a user has manually worked around the
> issue by generating a client.crash keyring, and adding a [client.crash]
> section, as described in [1]:
> 
> [client.crash]
>     key = <yourbase64key>
> 
> ... after the upgrade, this user will end up with the following
> [client.crash] section:
> 
> [client.crash]
> key = <yourbase64key>
> keyring = /etc/pve/ceph/$cluster.$name.keyring
> 
> and the same keyring <yourbase64key> in
> /etc/pve/ceph/ceph.client.crash.keyring.
> 
> In my test this is not a problem, though (probably since both keys are
> the same).
> 
> [1] https://bugzilla.proxmox.com/show_bug.cgi?id=4759#c7

Oh, good catch! I'll correct this in a v4, I think. We want to ensure we're
only setting the keyring, in our case.

Thanks again for all the tests, much appreciated!