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kubelet: ignore /dev/kmsg error when running in userns

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oomwatcher.NewWatcher returns "open /dev/kmsg: operation not permitted" error,
when running with sysctl value `kernel.dmesg_restrict=1`.

The error is negligible for KubeletInUserNamespace.

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
This commit is contained in:
Akihiro Suda 2021-05-24 23:35:22 +09:00
parent 192790c52f
commit 26e83ac4d4
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GPG Key ID: 49524C6F9F638F1A
1 changed files with 18 additions and 3 deletions
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21
pkg/kubelet/kubelet.go
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@ -34,6 +34,7 @@ import (
"k8s.io/client-go/informers"
cadvisorapi "github.com/google/cadvisor/info/v1"
libcontaineruserns "github.com/opencontainers/runc/libcontainer/userns"
"k8s.io/mount-utils"
"k8s.io/utils/integer"
@ -481,7 +482,19 @@ func NewMainKubelet(kubeCfg *kubeletconfiginternal.KubeletConfiguration,
oomWatcher, err := oomwatcher.NewWatcher(kubeDeps.Recorder)
if err != nil {
return nil, err
if libcontaineruserns.RunningInUserNS() {
if utilfeature.DefaultFeatureGate.Enabled(features.KubeletInUserNamespace) {
// oomwatcher.NewWatcher returns "open /dev/kmsg: operation not permitted" error,
// when running in a user namespace with sysctl value `kernel.dmesg_restrict=1`.
klog.V(2).InfoS("Failed to create an oomWatcher (running in UserNS, ignoring)", "err", err)
oomWatcher = nil
} else {
klog.ErrorS(err, "Failed to create an oomWatcher (running in UserNS, Hint: enable KubeletInUserNamespace feature flag to ignore the error)")
return nil, err
}
} else {
return nil, err
}
}
clusterDNS := make([]net.IP, 0, len(kubeCfg.ClusterDNS))
@ -1360,8 +1373,10 @@ func (kl *Kubelet) initializeModules() error {
}
// Start out of memory watcher.
if err := kl.oomWatcher.Start(kl.nodeRef); err != nil {
return fmt.Errorf("failed to start OOM watcher %v", err)
if kl.oomWatcher != nil {
if err := kl.oomWatcher.Start(kl.nodeRef); err != nil {
return fmt.Errorf("failed to start OOM watcher: %w", err)
}
}
// Start resource analyzer