Windows: subpath mount changes on a container restart if the environment variable changes

[claudiubelu]

What happened:

The test [k8s.io] Variable Expansion should not change the subpath mount on a container restart if the environment variable changes [sig-storage][Slow] [Conformance] fails on Windows. On container restart, the subpath mount changes.

The test does the following:

• spawns a Pod with an EmptyDir volume mounted in 2 locations: /volume_mount and subpath_mount (the 2nd one has a subpath expr set, taken from metadata.annotations['mysubpath'])
• the pod has a liveness probe that checks for the file /subpath_mount/test.log
• the test updates metadata.annotations['mysubpath'] to a different value.
• the test then deletes the file /subpath_mount/test.log and then waits for the container restart because of the liveness probe.
• the test recreates the /subpath_mount/test.log
• the test asserts that /volume_mount/foo/test.log exists, and that /volume_mount/newsubpath/test.log does not.

The test fails on the assertions on Windows.

What you expected to happen:

The container volume subpath should not change on container restart.

How to reproduce it (as minimally and precisely as possible):

kubectl create -f liveness.yaml

# check that test.log exists.
kubectl exec -n subpath-test-ns subpath-test -- ls /subpath_mount

# create /volume_mount/bar/test.log and /volume_mount/bar/tender
kubectl exec -n subpath-test-ns subpath-test -- /bin/bash -c "mkdir -p /volume_mount/bar && touch /volume_mount/bar/test.log && touch /volume_mount/bar/tender"

# update the pod volume subpath.
kubectl patch pod -n subpath-test-ns subpath-test -p '{"metadata":{"annotations":{"mysubpath":"bar"}}}'

# trigger the restart by deleting the file checked by the liveness probe.
kubectl exec -n subpath-test-ns subpath-test -- rm /subpath_mount/test.log

# check the /subpath_mount contents. It shouldn't contain test.log or tender.
kubectl exec -n subpath-test-ns subpath-test -- ls /subpath_mount

liveness.yaml:

apiVersion: v1
items:
- apiVersion: v1
  kind: Namespace
  metadata:
    name: subpath-test-ns
- apiVersion: v1
  kind: Pod
  metadata:
    annotations:
      kubernetes.io/psp: e2e-test-privileged-psp
      mysubpath: foo
    name: subpath-test
    namespace: subpath-test-ns
  spec:
    containers:
    - command:
      - /bin/sh
      - -ec
      - 'sleep 100000'
      env:
      - name: POD_NAME
        valueFrom:
          fieldRef:
            apiVersion: v1
            fieldPath: metadata.annotations['mysubpath']
      image: claudiubelu/busybox:1.29
      imagePullPolicy: Always
      livenessProbe:
        exec:
          command:
          - /bin/sh
          - -c
          - 'cat /subpath_mount/test.log'
        failureThreshold: 1
        initialDelaySeconds: 10
        periodSeconds: 2
        successThreshold: 1
        timeoutSeconds: 1
      name: dapi-container
      volumeMounts:
      - mountPath: /subpath_mount
        name: workdir1
        subPathExpr: $(POD_NAME)
      - mountPath: /volume_mount
        name: workdir1
    initContainers:
    - command:
      - sh
      - -c
      - mkdir -p /volume_mount/foo; touch /volume_mount/foo/test.log
      image: claudiubelu/busybox:1.29
      imagePullPolicy: Always
      name: init-volume-50ab29f4
      volumeMounts:
      - mountPath: /subpath_mount
        name: workdir1
      - mountPath: /volume_mount
        name: workdir1
    volumes:
    - emptyDir: {}
      name: workdir1
kind: List

Anything else we need to know?:

/sig windows

Environment:

• Kubernetes version (use kubectl version): v1.18
• Cloud provider or hardware configuration: N/A
• OS (e.g: cat /etc/os-release): Windows Server 2019
• Kernel (e.g. uname -a): N/A
• Install tools: N/A
• Network plugin and version (if this is a network-related bug): N/A
• Others: N/A

[claudiubelu]

/sig windows

[marosset]

/priority critical-urgent
/kind failing-test
/milestone v1.19

[craiglpeters]

Due to the discussion in #89629 this is no longer a priority