[ovs-dev] [PATCH] Make pidfile_is_running more robust against empty pidfiles

Numan Siddique nusiddiq at redhat.com
Tue Aug 20 11:36:12 UTC 2019


On Tue, Aug 20, 2019 at 2:52 PM Ilya Maximets <i.maximets at samsung.com>
wrote:

> On 20.08.2019 12:16, Ilya Maximets wrote:
> > On 20.08.2019 11:48, Numan Siddique wrote:
> >>
> >>
> >> On Wed, Aug 14, 2019 at 9:21 PM Michele Baldessari <michele at acksyn.org
> <mailto:michele at acksyn.org>> wrote:
> >>
> >>     On Wed, Aug 14, 2019 at 02:28:13PM +0300, Ilya Maximets wrote:
> >>     > On 14.08.2019 11:39, Michele Baldessari wrote:
> >>     > > In some of our destructive testing of ovn-dbs inside containers
> managed
> >>     > > by pacemaker we reached a situation where /var/run/openvswitch
> had
> >>     > > empty .pid files. The current code does not deal well with them
> >>     > > and pidfile_is_running() returns true in such a case and this
> confuses
> >>     > > the OCF resource agent.
> >>     > >
> >>     > > - Before this change:
> >>     > > Inside a container run:
> >>     > >   killall ovsdb-server;
> >>     > >   echo -n '' > /var/run/openvswitch/ovnnb_db.pid; echo -n '' >
> /var/run/openvswitch/ovnsb_db.pid
> >>     > >
> >>     > > We will observe that the cluster is unable to ever recover
> because
> >>     > > it believes the ovn processes to be running when they really
> aren't and
> >>     > > eventually just fails:
> >>     > >  podman container set: ovn-dbs-bundle [
> 192.168.24.1:8787/rhosp15/openstack-ovn-northd:pcmklatest <
> http://192.168.24.1:8787/rhosp15/openstack-ovn-northd:pcmklatest>]
> >>     > >    ovn-dbs-bundle-0     (ocf::ovn:ovndb-servers):       Master
> controller-0
> >>     > >    ovn-dbs-bundle-1     (ocf::ovn:ovndb-servers):       Stopped
> controller-1
> >>     > >    ovn-dbs-bundle-2     (ocf::ovn:ovndb-servers):       Slave
> controller-2
> >>     > >
> >>     > > - After this change the cluster is able to recover from this
> state and
> >>     > > correctly start the resource:
> >>     > >  podman container set: ovn-dbs-bundle [
> 192.168.24.1:8787/rhosp15/openstack-ovn-northd:pcmklatest <
> http://192.168.24.1:8787/rhosp15/openstack-ovn-northd:pcmklatest>]
> >>     > >    ovn-dbs-bundle-0     (ocf::ovn:ovndb-servers):       Master
> controller-0
> >>     > >    ovn-dbs-bundle-1     (ocf::ovn:ovndb-servers):       Slave
> controller-1
> >>     > >    ovn-dbs-bundle-2     (ocf::ovn:ovndb-servers):       Slave
> controller-2
> >>     > >
> >>     > > Signed-off-by: Michele Baldessari <michele at acksyn.org <mailto:
> michele at acksyn.org>>
> >>     > > ---
> >>     > >  ovn/utilities/ovn-ctl | 2 +-
> >>     > >  1 file changed, 1 insertion(+), 1 deletion(-)
> >>     > >
> >>     > > diff --git a/ovn/utilities/ovn-ctl b/ovn/utilities/ovn-ctl
> >>     > > index 7e5cd469c83c..65f03e28ddba 100755
> >>     > > --- a/ovn/utilities/ovn-ctl
> >>     > > +++ b/ovn/utilities/ovn-ctl
> >>     > > @@ -35,7 +35,7 @@
> ovn_northd_db_conf_file="$etcdir/ovn-northd-db-params.conf"
> >>     > >
> >>     > >  pidfile_is_running () {
> >>     > >      pidfile=$1
> >>     > > -    test -e "$pidfile" && pid=`cat "$pidfile"` && pid_exists
> "$pid"
> >>     > > +    test -e "$pidfile" && [ -s "$pidfile" ] && pid=`cat
> "$pidfile"` && pid_exists "$pid"
> >>     >
> >>     > Hi. Thanks for the fix!
> >>     >
> >>     > Maybe it's better to add additional check for an empty argument to
> >>     > 'pid_exists' function instead? This will cover more cases like
> invocations
> >>     > from the utilities/ovs-lib.in <
> https://protect2.fireeye.com/url?k=64579ecddf75e065.64561582-0f6314ee43bf7086&u=http://ovs-lib.in
> >.
> >>     >
> >>     > I think, you may also add following tag to commit-message in this
> case:
> >>     > Fixes: 3028ce2595c8 ("ovs-lib: Allow "status" command to work as
> non-root.")
> >>     >
> >>     > This patch also will be needed in ovn-org/ovn repository too.
> >>     > (Use 'PATCH ovn' subject prefix while sending patches targeted
> for ovn repo.)
> >>     >
> >>     > Best regards, Ilya Maximets.
> >>
> >>     Thanks for the feedback Ilya, I have amended things (hopefully
> correctly) in
> >>     http://patchwork.ozlabs.org/patch/1147111/ (I could not figure out
> how
> >>     to update an existing patch in patchwork, I hope this is okay)
> >>
> >>
> >> Hi Michele and Ilya,
> >>
> >> I applied this fix to the OVN repo. It's possible that the fix to
> address this issue in ovs-lib.in <
> https://protect2.fireeye.com/url?k=64579ecddf75e065.64561582-0f6314ee43bf7086&u=http://ovs-lib.in>
> could
> >> be missing in some deployments if older ovs version is used. I thought
> its no harm in having
> >> the fixes in both ovn-ctl and ovs-lib.in <
> https://protect2.fireeye.com/url?k=64579ecddf75e065.64561582-0f6314ee43bf7086&u=http://ovs-lib.in
> >.
> >>
> >
> > Hi Numan,
> >
> > There was already v2 for this patch (a bit renamed):
> > OVS:
> https://mail.openvswitch.org/pipermail/ovs-dev/2019-August/361678.html
> > OVN:
> https://mail.openvswitch.org/pipermail/ovs-dev/2019-August/361679.html
>
> Sorry, maybe I misunderstood what you wanted to do.
> Do you suggest to apply v1 to OVN repo and v2 to OVS repo?
> What about applying v2 to OVN repo?
>
>
Yes.  v1 to OVN repo and v2 to OVS repo.
OVN repo doesn't have the ovs-lib.in file. So v2 won't apply there.

We could apply v1 to OVS repo too, but that wouldn't make sense as we may
delete the ovn folder once
this patch is accepted - https://patchwork.ozlabs.org/patch/1147617/

Thanks
Numan


> >
> > Best regards, Ilya Maximets.
> >
> >
>


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