kubelet: fix panic triggered when playing with a wip CRI

[bjorand]

I'm writing a custom container runtime and I encounter a kubelet panic:

I0325 22:39:20.613544    9913 kuberuntime_sandbox.go:296] "Pod Sandbox status doesn't have network information, cannot report IPs" pod="default/httpd-86d666c486-s58ls"
I0325 22:39:20.620552    9913 kubelet.go:2098] "SyncLoop (PLEG): event for pod" pod="default/httpd-86d666c486-s58ls" event=&{ID:7d04550d-2db8-4725-91d8-316f3fb95636 Type:ContainerStarted Data:7d04550d-2db8-4725-91d8-316f3fb95636}
E0325 22:39:20.622081    9913 runtime.go:79] Observed a panic: "invalid memory address or nil pointer dereference" (runtime error: invalid memory address or nil pointer dereference)
goroutine 344 [running]:
k8s.io/apimachinery/pkg/util/runtime.logPanic({0x438b5a0, 0x77750e0})
  /home/meister/go/src/github.com/kubernetes/kubernetes/vendor/k8s.io/apimachinery/pkg/util/runtime/runtime.go:75 +0xb4
k8s.io/apimachinery/pkg/util/runtime.HandleCrash({0x0, 0x0, 0x0})
  /home/meister/go/src/github.com/kubernetes/kubernetes/vendor/k8s.io/apimachinery/pkg/util/runtime/runtime.go:49 +0x8c
panic({0x438b5a0, 0x77750e0})
  /usr/local/go/src/runtime/panic.go:1038 +0x25b
k8s.io/kubernetes/pkg/kubelet/kuberuntime.(*kubeGenericRuntimeManager).podSandboxChanged(0xc0008c29a0, 0xc000eb7000, 0xc000ed4980)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/kuberuntime/kuberuntime_manager.go:500 +0x2b5
k8s.io/kubernetes/pkg/kubelet/kuberuntime.(*kubeGenericRuntimeManager).computePodActions(0xc0008c29a0, 0xc000eb7000, 0xc000ed4980)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/kuberuntime/kuberuntime_manager.go:529 +0x225
k8s.io/kubernetes/pkg/kubelet/kuberuntime.(*kubeGenericRuntimeManager).SyncPod(0xc0008c29a0, 0xc000eb7000, 0xc000ed4980, {0x77e7ed8, 0x0, 0x0}, 0xc00009da40)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/kuberuntime/kuberuntime_manager.go:714 +0x89
k8s.io/kubernetes/pkg/kubelet.(*Kubelet).syncPod(0xc000a68000, {0x53b6a50, 0xc000e73880}, 0x0, 0xc000eb7000, 0x0, 0xc000ed4980)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/kubelet.go:1718 +0x23c4
k8s.io/kubernetes/pkg/kubelet.(*podWorkers).managePodLoop.func1(0xc000b3dee0, 0xc0004c3680, 0xc000eb7000, 0xc000b3dea8)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/pod_workers.go:935 +0x333
k8s.io/kubernetes/pkg/kubelet.(*podWorkers).managePodLoop(0xc0004c3680, 0xc000e8e960)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/pod_workers.go:940 +0x469
k8s.io/kubernetes/pkg/kubelet.(*podWorkers).UpdatePod.func1(0xc0004c3680, 0xc000e8e960)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/pod_workers.go:736 +0x72
created by k8s.io/kubernetes/pkg/kubelet.(*podWorkers).UpdatePod
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/pod_workers.go:734 +0x2005
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
  panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x3b99615]

goroutine 344 [running]:
k8s.io/apimachinery/pkg/util/runtime.HandleCrash({0x0, 0x0, 0x0})
  /home/meister/go/src/github.com/kubernetes/kubernetes/vendor/k8s.io/apimachinery/pkg/util/runtime/runtime.go:56 +0x109
panic({0x438b5a0, 0x77750e0})
  /usr/local/go/src/runtime/panic.go:1038 +0x25b
k8s.io/kubernetes/pkg/kubelet/kuberuntime.(*kubeGenericRuntimeManager).podSandboxChanged(0xc0008c29a0, 0xc000eb7000, 0xc000ed4980)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/kuberuntime/kuberuntime_manager.go:500 +0x2b5
k8s.io/kubernetes/pkg/kubelet/kuberuntime.(*kubeGenericRuntimeManager).computePodActions(0xc0008c29a0, 0xc000eb7000, 0xc000ed4980)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/kuberuntime/kuberuntime_manager.go:529 +0x225
k8s.io/kubernetes/pkg/kubelet/kuberuntime.(*kubeGenericRuntimeManager).SyncPod(0xc0008c29a0, 0xc000eb7000, 0xc000ed4980, {0x77e7ed8, 0x0, 0x0}, 0xc00009da40)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/kuberuntime/kuberuntime_manager.go:714 +0x89
k8s.io/kubernetes/pkg/kubelet.(*Kubelet).syncPod(0xc000a68000, {0x53b6a50, 0xc000e73880}, 0x0, 0xc000eb7000, 0x0, 0xc000ed4980)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/kubelet.go:1718 +0x23c4
k8s.io/kubernetes/pkg/kubelet.(*podWorkers).managePodLoop.func1(0xc000b3dee0, 0xc0004c3680, 0xc000eb7000, 0xc000b3dea8)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/pod_workers.go:935 +0x333
k8s.io/kubernetes/pkg/kubelet.(*podWorkers).managePodLoop(0xc0004c3680, 0xc000e8e960)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/pod_workers.go:940 +0x469
k8s.io/kubernetes/pkg/kubelet.(*podWorkers).UpdatePod.func1(0xc0004c3680, 0xc000e8e960)
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/pod_workers.go:736 +0x72
created by k8s.io/kubernetes/pkg/kubelet.(*podWorkers).UpdatePod
  /home/meister/go/src/github.com/kubernetes/kubernetes/pkg/kubelet/pod_workers.go:734 +0x2005

/kind bug

NONE

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: bjorand / name: Benjamin Jorand (3c65728)

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[k8s-ci-robot]

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[ehashman]

/priority backlog
/triage accepted
/lgtm

[ehashman]

/ok-to-test

[bjorand]

/retest

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bjorand, mrunalp

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