Make pid_exists() more robust against empty pid argument
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]
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
Let's make sure pid_exists() returns false when the pid is an empty
string.
- 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]
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
Fixes: 3028ce2595c8 ("ovs-lib: Allow "status" command to work as non-root.") Signed-off-by: Michele Baldessari <michele@acksyn.org> Signed-off-by: Ben Pfaff <blp@ovn.org>