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72 lines
2.6 KiB
Plaintext
72 lines
2.6 KiB
Plaintext
// Module included in the following assemblies:
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//
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// * scalability_and_performance/optimization/optimizing-cpu-usage.adoc
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:_mod-docs-content-type: PROCEDURE
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[id="supporting-encapsulation_{context}"]
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= Inspecting encapsulated namespaces
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You can inspect Kubernetes-specific mount points in the cluster host operating system for debugging or auditing purposes by using the `kubensenter` script that is available in {op-system-first}.
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SSH shell sessions to the cluster host are in the default namespace.
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To inspect Kubernetes-specific mount points in an SSH shell prompt, you need to run the `kubensenter` script as root.
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The `kubensenter` script is aware of the state of the mount encapsulation, and is safe to run even if encapsulation is not enabled.
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[NOTE]
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====
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`oc debug` remote shell sessions start inside the Kubernetes namespace by default.
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You do not need to run `kubensenter` to inspect mount points when you use `oc debug`.
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====
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If the encapsulation feature is not enabled, the `kubensenter findmnt` and `findmnt` commands return the same output, regardless of whether they are run in an `oc debug` session or in an SSH shell prompt.
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.Prerequisites
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* You have installed the OpenShift CLI (`oc`).
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* You have logged in as a user with `cluster-admin` privileges.
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* You have configured SSH access to the cluster host.
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.Procedure
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. Open a remote SSH shell to the cluster host. For example:
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+
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[source,terminal]
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----
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$ ssh core@<node_name>
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----
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. Run commands using the provided `kubensenter` script as the root user.
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To run a single command inside the Kubernetes namespace, provide the command and any arguments to the `kubensenter` script.
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For example, to run the `findmnt` command inside the Kubernetes namespace, run the following command:
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+
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[source,terminal]
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----
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[core@control-plane-1 ~]$ sudo kubensenter findmnt
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----
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+
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.Example output
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[source,terminal]
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----
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kubensenter: Autodetect: kubens.service namespace found at /run/kubens/mnt
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TARGET SOURCE FSTYPE OPTIONS
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/ /dev/sda4[/ostree/deploy/rhcos/deploy/32074f0e8e5ec453e56f5a8a7bc9347eaa4172349ceab9c22b709d9d71a3f4b0.0]
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| xfs rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota
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shm tmpfs
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...
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----
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. To start a new interactive shell inside the Kubernetes namespace, run the `kubensenter` script without any arguments:
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+
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[source,terminal]
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----
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[core@control-plane-1 ~]$ sudo kubensenter
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----
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+
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.Example output
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[source,terminal]
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----
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kubensenter: Autodetect: kubens.service namespace found at /run/kubens/mnt
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----
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