fix: don't mount D-Bus socket via mount under recursive bind mount

`/var/run` was mounted from `/run`, and D-Bus socket to `/var/run/dbus/`
path, so when the container is stopped, container mounts are removed,
but on the host side mount propagates back, so D-Bus socket gets
propagated back to the host `/run`, and on the next kubelet restart
process continues adding even more mount levels exponentially.
Eventually on kubelet restart kernel resources are exhausted and the
node freezes.

Signed-off-by: Andrey Smirnov <[email protected]>

internal/app/machined/pkg/system/services/kubelet.go

@@ -120,7 +120,6 @@ func (k *Kubelet) Runner(r runtime.Runtime) (runner.Runner, error) {
 		{Type: "bind", Destination: "/etc/cni", Source: "/etc/cni", Options: []string{"rbind", "rshared", "rw"}},
 		{Type: "bind", Destination: "/usr/libexec/kubernetes", Source: "/usr/libexec/kubernetes", Options: []string{"rbind", "rshared", "rw"}},
 		{Type: "bind", Destination: "/var/run", Source: "/run", Options: []string{"rbind", "rshared", "rw"}},
-		{Type: "bind", Destination: "/var/run/dbus/system_bus_socket", Source: constants.DBusClientSocketPath, Options: []string{"bind", "rw"}},
 		{Type: "bind", Destination: "/var/lib/containerd", Source: "/var/lib/containerd", Options: []string{"rbind", "rshared", "rw"}},
 		{Type: "bind", Destination: "/var/lib/kubelet", Source: "/var/lib/kubelet", Options: []string{"rbind", "rshared", "rw"}},
 		{Type: "bind", Destination: "/var/log/containers", Source: "/var/log/containers", Options: []string{"rbind", "rshared", "rw"}},

pkg/machinery/constants/constants.go

@@ -658,7 +658,7 @@ const (
 	DBusServiceSocketPath = SystemRunPath + "/dbus/service.socket"
 
 	// DBusClientSocketPath is the path to the D-Bus socket for the kubelet to connect to.
-	DBusClientSocketPath = SystemRunPath + "/dbus/client.socket"
+	DBusClientSocketPath = "/run/dbus/system_bus_socket"
 )
 
 // See https://linux.die.net/man/3/klogctl