`termination-log` is not available when mounting `/dev` in containers

[maybe-sybr]

I've found that the kubernetes-sigs/sig-storage-local-static-provisioner attempts to mount /dev from the host in its provisioner container, which causes issues when running the daemonset under u7s. Given that there are no reports of this being broken on their issue tracker, I presumed it was an unexpected failure case for u7s rather than them doing the wrong thing (feel free to correct me on this).

It's fairly trivial to work around the issue by setting the terminationMessagePath for the container, although it's not clear to me if this would result in termination messages being lost. See the badness.yaml snippet below and its failure events in describe pod badness:

$ cat badness.yaml
apiVersion: v1
kind: Pod
metadata:
  name: badness
  labels:
    app: badness
spec:
  containers:
  - image: busybox
    name: badness
    command: ["sleep", "infinity"]
    volumeMounts:
      - name: shared-dev
        mountPath: /dev
    #terminationMessagePath: /var/run/termination-log
  volumes:
    - name: shared-dev
      hostPath:
        path: /dev/
$ kubectl apply -f badness.yaml
pod/badness created
$ kubectl describe pod badness
...
Events:
  Type     Reason     Age              From          Message
  ----     ------     ----             ----          -------
  Normal   Scheduled  <unknown>                      Successfully assigned default/user-storage-provisioner-7sn8s to host
  Normal   Pulled     2s (x2 over 2s)  kubelet, host Container image "quay.io/external_storage/local-volume-provisioner:v2.3.4" already present on machine
  Warning  Failed     2s               kubelet, host Error: container create failed: open `/home/user/.local/share/usernetes/containers/storage/overlay/6d3e5e577d2174a25f2947faa0af0b5e68af13bedb662eaaf59068f173640091/merged/termination-log`: No such file or directory
  Warning  Failed     2s               kubelet, host Error: container create failed: open `/home/user/.local/share/usernetes/containers/storage/overlay/273772f44ad6a6e0d55af8b2d3dadb154c734084d4bc82b7f7e4f0cd7e8bda8e/merged/termination-log`: No such file or directory

Uncommenting the terminationMessagePath in badness.yaml makes the pod start happily.

[AkihiroSuda]

Is this only for crio? Does it work with containerd?

[maybe-sybr]

I've not been able to try with containerd yet. I'll try it when I have a bit of free time and get back to you.

[maybe-sybr]

@AkihiroSuda - appears to break under containerd as well.

$ kubectl describe pod
Name:         badness
Namespace:    default
Priority:     0
Node:         host/10.0.42.100
Start Time:   Wed, 16 Sep 2020 10:06:53 +1000
Labels:       app=badness
Annotations:  kubectl.kubernetes.io/last-applied-configuration:
                {"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"labels":{"app":"badness"},"name":"badness","namespace":"default"},"spec":{"c...
Status:       Running
IP:           10.88.1.23
Containers:
  badness:
    Container ID:  containerd://23de93c3fb8413c3ed9bf7ae6026962982038cad7288d046c488efd9bd016379
    Image:         busybox
    Image ID:      docker.io/library/busybox@sha256:d366a4665ab44f0648d7a00ae3fae139d55e32f9712c67accd604bb55df9d05a
    Port:          <none>
    Host Port:     <none>
    Command:
      sleep
      infinity
    State:          Waiting
      Reason:       CrashLoopBackOff
    Last State:     Terminated
      Reason:       StartError
      Message:      failed to create containerd task: OCI runtime create failed: open `/run/.ro966304741/user/1000/usernetes/containerd/io.containerd.runtime.v2.task/k8s.io/23de93c3fb8413c3ed9bf7ae6026962982038cad7288d046c488efd9bd016379/rootfs/termination-log`: No such file or directory: unknown
      Exit Code:    128
      Started:      Thu, 01 Jan 1970 10:00:00 +1000
      Finished:     Wed, 16 Sep 2020 10:07:21 +1000
    Ready:          False
    Restart Count:  2
    Environment:    <none>
    Mounts:
      /dev from shared-dev (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-dgbbv (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             False
  ContainersReady   False
  PodScheduled      True
Volumes:
  shared-dev:
    Type:          HostPath (bare host directory volume)
    Path:          /dev/
    HostPathType:
  default-token-dgbbv:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-dgbbv
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type     Reason     Age                From          Message
  ----     ------     ----               ----          -------
  Normal   Scheduled  <unknown>                        Successfully assigned default/badness to host
  Normal   Pulled     34s                kubelet, host Successfully pulled image "busybox" in 7.553314539s
  Normal   Pulled     30s                kubelet, host Successfully pulled image "busybox" in 2.673382993s
  Normal   Pulling    16s (x3 over 41s)  kubelet, host Pulling image "busybox"
  Normal   Created    14s (x3 over 33s)  kubelet, host Created container badness
  Warning  Failed     14s (x3 over 33s)  kubelet, host Error: failed to create containerd task: OCI runtime create failed: open `/run/.ro966304741/user/1000/usernetes/containerd/io.containerd.runtime.v2.task/k8s.io/badness/rootfs/termination-log`: No such file or directory: unknown
  Normal   Pulled     14s                kubelet, host Successfully pulled image "busybox" in 2.409908214s
  Warning  BackOff    2s (x4 over 29s)   kubelet, host Back-off restarting failed container