Fix pods stuck terminating.

If the kubelet container is restarted on a host (during upgrades, or manually)
the bind mounts duplicate into /rootfs and kubelet cannot unmount these.

This leads to stuck terminating pods that must be resolved with either --force
or restart of kubelet container.

Adding 'rslave' means that when the kubelet unmounts volumes at /var/lib/kubelet/pods
this propogates to the host (using 'rshared'), and back into the container in /rootfs.

This bug was likely introduced when mounting of /rootfs was added[0].

[0] https://opendev.org/openstack/magnum/commit/1994e9448a4d131e6305b68e49f1fdcdb5420cef

Change-Id: I44f80ccc97c0eeab98f1edbe4a22763732b7f4da
(cherry picked from commit b318560)
(cherry picked from commit ed63a0d626b030f7d5fa81fe3341b7e8d8ef4a2b)

Author: dalees

magnum/drivers/common/templates/kubernetes/fragments/configure-kubernetes-master.sh

@@ -187,7 +187,7 @@ ExecStart=/bin/bash -c '/usr/bin/podman run --name kubelet \\
     --pid host \\
     --network host \\
     --entrypoint /hyperkube \\
-    --volume /:/rootfs:ro \\
+    --volume /:/rootfs:rslave,ro \\
     --volume /etc/cni/net.d:/etc/cni/net.d:ro,z \\
     --volume /etc/kubernetes:/etc/kubernetes:ro,z \\
     --volume /usr/lib/os-release:/usr/lib/os-release:ro \\

magnum/drivers/common/templates/kubernetes/fragments/configure-kubernetes-minion.sh

@@ -85,7 +85,7 @@ ExecStart=/bin/bash -c '/usr/bin/podman run --name kubelet \\
     --pid host \\
     --network host \\
     --entrypoint /hyperkube \\
-    --volume /:/rootfs:ro \\
+    --volume /:/rootfs:rslave,ro \\
     --volume /etc/cni/net.d:/etc/cni/net.d:ro,z \\
     --volume /etc/kubernetes:/etc/kubernetes:ro,z \\
     --volume /usr/lib/os-release:/usr/lib/os-release:ro \\