Kubelet makes sure that /var/lib/kubelet is rshared when it starts.
If not, it bind-mounts it with rshared propagation to containers
that mount volumes to /var/lib/kubelet can benefit from mount propagation.
Automatic merge from submit-queue
Run mount in its own systemd scope.
Kubelet needs to run /bin/mount in its own cgroup.
- When kubelet runs as a systemd service, "systemctl restart kubelet" may kill all processes in the same cgroup and thus terminate fuse daemons that are needed for gluster and cephfs mounts.
- When kubelet runs in a docker container, restart of the container kills all fuse daemons started in the container.
Killing fuse daemons is bad, it basically unmounts volumes from running pods.
This patch runs mount via "systemd-run --scope /bin/mount ...", which makes sure that any fuse daemons are forked in its own systemd scope (= cgroup) and they will survive restart of kubelet's systemd service or docker container.
This helps with #34965
As a downside, each new fuse daemon will run in its own transient systemd service and systemctl output may be cluttered.
@kubernetes/sig-storage-pr-reviews
@kubernetes/sig-node-pr-reviews
```release-note
fuse daemons for GlusterFS and CephFS are now run in their own systemd scope when Kubernetes runs on a system with systemd.
```
Kubelet needs to run /bin/mount in its own cgroup.
- When kubelet runs as a systemd service, "systemctl restart kubelet" may kill
all processes in the same cgroup and thus terminate fuse daemons that are
needed for gluster and cephfs mounts.
- When kubelet runs in a docker container, restart of the container kills all
fuse daemons started in the container.
Killing fuse daemons is bad, it basically unmounts volumes from running pods.
This patch runs mount via "systemd-run --scope /bin/mount ...", which makes
sure that any fuse daemons are forked in its own systemd scope (= cgroup) and
they will survive restart of kubelet's systemd service or docker container.
As a downside, each new fuse daemon will run in its own transient systemd
service and systemctl output may be cluttered.
NsEnterMounter should not stop parsing findmnt output on the first space but
on the last one, just in case the mount point name itself contains a space.
Added IsNotMountPoint method to mount utils (pkg/util/mount/mount.go)
Added UnmountMountPoint method to volume utils (pkg/volume/util/util.go)
Call UnmountMountPoint method from local storage (pkg/volume/local/local.go)
IsLikelyNotMountPoint behavior was not modified, so the logic/behavior for UnmountPath is not modified
Currently kubelet volume management works on the concept of desired
and actual world of states. The volume manager periodically compares the
two worlds and perform volume mount/unmount and/or attach/detach
operations. When kubelet restarts, the cache of those two worlds are
gone. Although desired world can be recovered through apiserver, actual
world can not be recovered which may cause some volumes cannot be cleaned
up if their information is deleted by apiserver. This change adds the
reconstruction of the actual world by reading the pod directories from
disk. The reconstructed volume information is added to both desired
world and actual world if it cannot be found in either world. The rest
logic would be as same as before, desired world populator may clean up
the volume entry if it is no longer in apiserver, and then volume
manager should invoke unmount to clean it up.
In nsenter_mount.go/isLikelyNotMountPoint function, the returned output
from findmnt command misses the last letter. Modify the code to make sure
that output has the full target path. fix#26421#25056#22911
Kubelet was not able to mount volumes when running inside a container and
using nsenter mounter,
NsenterMounter.IsLikelyNotMountPoint() should return ErrNotExist when the
checked directory does not exists as the regular mounted does this and
some volume plugins depend on this behavior.
IsLikelyNotMountPoint determines if a directory is not a mountpoint.
It is fast but not necessarily ALWAYS correct. If the path is in fact
a bind mount from one part of a mount to another it will not be detected.
mkdir /tmp/a /tmp/b; mount --bin /tmp/a /tmp/b; IsLikelyNotMountPoint("/tmp/b")
will return true. When in fact /tmp/b is a mount point. So this patch
renames the function and switches it from a positive to a negative (I
could think of a good positive name). This should make future users of
this function aware that it isn't quite perfect, but probably good
enough.
Di Xu