[ClusterLabs] resource agent OCF_HEARTBEAT_GALERA issue/broken - ?

[Reid Wahl]

On Wed, Jul 27, 2022 at 2:08 AM lejeczek via Users
<users at clusterlabs.org> wrote:
>
>
>
> On 26/07/2022 20:56, Reid Wahl wrote:
> > On Tue, Jul 26, 2022 at 4:21 AM lejeczek via Users
> > <users at clusterlabs.org> wrote:
> >> Hi guys
> >>
> >> I set up a clone of a new instance of mariadb galera - which otherwise,
> >> outside of pcs works - but I see something weird.
> >>
> >> Firstly cluster claims it's all good:
> >>
> >> -> $ pcs status --full
> >> ...
> >>
> >>     * Clone Set: mariadb-apps-clone [mariadb-apps] (promotable):
> >>       * mariadb-apps    (ocf::heartbeat:galera):     Master
> >> sucker.internal.ccn
> >>       * mariadb-apps    (ocf::heartbeat:galera):     Master
> >> drunk.internal.ccn
> > Clearly the problem is that your server is drunk.
> >
> >> but that mariadb is _not_ started actually.
> >>
> >> In clone's attr I set:
> >>
> >> config=/apps/etc/mariadb-server.cnf
> >>
> >> I also for peace of mind set:
> >>
> >> datadir=/apps/mysql/data
> >>
> >> even tough '/apps/etc/mariadb-server.cnf' declares that & other bits -
> >> again, works outside of pcs.
> >>
> >> Then I see in pacemaker logs:
> >>
> >> notice: mariadb-apps_start_0 at drunk.internal.ccn output [ 220726 11:56:13
> >> mysqld_safe Logging to '/tmp/tmp.On5VnzOyaF'.\n220726 11:56:13
> >> mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql\n ]
> >>
> >> .. and I think what the F?
> >>
> >> resource-agents-4.9.0-22.el8.x86_64
> >>
> >> All thoughts share are much appreciated.
> >>
> >> many thanks, L.
> >>
> > How do you start mariadb outside of pacemaker's control?
> simply by:
> -> $ sudo -u mysql /usr/libexec/mysqld
> --defaults-file=/apps/etc/mariadb-server.cnf
> --wsrep-new-clusterrep

Got it. FWIW, `--wsrep-new-clusterrep` doesn't appear to be a valid
option (no search results and nothing in the help output). Maybe this
is a typo in the email; `--wsrep-new-cluster` is valid.

> >
> > It seems that *something* is running, based on the "Starting" message
> > and the fact that the resources are still in Started state...
> Yes, a "regular" instance of galera (which outside of
> pacemaker works with "regular" systemd) is running as ofc
> one resource already.
>
> >
> > The logic to start and promote the galera resource is contained within
> > /usr/lib/ocf/resource.d/heartbeat/galera and
> > /usr/lib/ocf/lib/heartbeat/mysql-common.sh. I encourage you to inspect
> > those for any relevant differences between your own startup method and
> > that of the resource agent.
> >
> > As one example, note that the resource agent uses mysqld_safe by
> > default. This is configurable via the `binary` option for the
> > resource. Be sure that you've looked at all the available options
> > (`pcs resource describe ocf:heartbeat:galera`) and configured any of
> > them that you need. You've definitely at least started that process
> > with config and datadir.
> log snippet I pasted was not to emphasize 'mysqld_safe' but
> the fact that resource does:
> ...
> Starting mysqld daemon with databases from /var/lib/mysql
> ...
>
> Yes, I did check man pages for options and if if you suggest
> checking source code then I say that's  case for a bug report.

For something like pacemaker, I wouldn't point a user to the code.
galera and mysql-common.sh are shell scripts, so they're easier to
interpret. The idea was "maybe you can find a discrepancy between how
the scripts are starting mysql, and how you're manually starting
mysql."

Filing a bug might be reasonable. I don't have much hands-on
experience with mysql or with this resource agent.

> I tried my best to make it clear, doubt can do that better
> but I'll re-try:
> a) bits needed to run a "new/second" instance are all in
> 'mariadb-server.cnf' and galera works outside of pacemaker
> (cmd above)
> b) if I use attrs: 'datadir' & 'config' yet resource tells
> me "..daemon with databases from /var/lib/mysql..." then..
> people looking into the code should perhaps be you (as
> Redhat employee) and/or other authors/developers - if I
> filed it as BZ - no?
>
> It should be easily reproducible, have:
> 1) a galera (as a 2nd/3rd/etc. instance, outside & with
> different settings from "standard" OS's rpm installation)
> work & tested
> 2) set up a resource:
> -> $ pcs resource create mariadb-apps ocf:heartbeat:galera
> cluster_host_map="drunk.internal.ccn:10.0.1.6;sucker.internal.ccn:10.0.1.7"
> config="/apps/etc/mariadb-server.cnf"
> wsrep_cluster_address="gcomm://10.0.1.6:5567,10.0.1.7:5567"
> user=mysql group=mysql check_user="pacemaker"
> check_passwd="pacemaker#9897" op monitor OCF_CHECK_LEVEL="0"
> timeout="30s" interval="20s" op monitor role="Master"
> OCF_CHECK_LEVEL="0" timeout="30s" interval="10s" op monitor
> role="Slave" OCF_CHECK_LEVEL="0" timeout="30s"
> interval="30s" promotable promoted-max=2 meta
> failure-timeout=30s

The datadir option isn't specified in the resource create command
above. If datadir not explicitly set, then the resource agent uses
/var/lib/mysql by default:
```
mysql_common_start()
{
    local mysql_extra_params="$1"
    local pid

    $SU - $OCF_RESKEY_user -s /bin/sh -c \
    "${OCF_RESKEY_binary} --defaults-file=$OCF_RESKEY_config \
    --pid-file=$OCF_RESKEY_pid \
    --socket=$OCF_RESKEY_socket \
    --datadir=$OCF_RESKEY_datadir \
    --log-error=$OCF_RESKEY_log \
    $OCF_RESKEY_additional_parameters \
    $mysql_extra_params >/dev/null 2>&1" &
    pid=$!
```

where OCF_RESKEY_datadir is set to /var/lib/mysql if you don't set it yourself.

As mentioned above, I'm not very familiar with mysql, but I would
expect the CLI --datadir=/var/lib/mysql option to override anything in
the defaults-file.

>
> and you should get (give version & evn is the same) see what
> I see - weird "misbehavior"
>
> many thanks, L.
>
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-- 
Regards,

Reid Wahl (He/Him)
Senior Software Engineer, Red Hat
RHEL High Availability - Pacemaker