OpenShift の様々な操作で使用する oc コマンドの Krew plugin をご紹介します。
Krew plugin は kubectl / oc コマンドに実装されている plugin 機能 ( kubectl plugin / oc plugin) に配布・管理機能を追加します。Krew plugin も plugin の1つとして実装されています。
執筆時点では、oc コマンドにおける Krew plugin の使用は Technology Preview となっています。
Install Krew plugin
上記ドキュメンから Link されている以下を参考に Krew plugin をインストールします。
$ (
> set -x; cd "$(mktemp -d)" &&
> OS="$(uname | tr '[:upper:]' '[:lower:]')" &&
> ARCH="$(uname -m | sed -e 's/x86_64/amd64/' -e 's/\(arm\)\(64\)\?.*/\1\2/' -e 's/aarch64$/arm64/')" &&
> KREW="krew-${OS}_${ARCH}" &&
> curl -fsSLO "https://github.com/kubernetes-sigs/krew/releases/latest/download/${KREW}.tar.gz" &&
> tar zxvf "${KREW}.tar.gz" &&
> ./"${KREW}" install krew
> )
++ mktemp -d
+ cd /tmp/tmp.RfH5SyD106
++ uname
++ tr '[:upper:]' '[:lower:]'
+ OS=linux
++ uname -m
++ sed -e s/x86_64/amd64/ -e 's/\(arm\)\(64\)\?.*/\1\2/' -e 's/aarch64$/arm64/'
+ ARCH=amd64
+ KREW=krew-linux_amd64
+ curl -fsSLO https://github.com/kubernetes-sigs/krew/releases/latest/download/krew-linux_amd64.tar.gz
+ tar zxvf krew-linux_amd64.tar.gz
./LICENSE
./krew-linux_amd64
+ ./krew-linux_amd64 install krew
Adding "default" plugin index from https://github.com/kubernetes-sigs/krew-index.git.
Updated the local copy of plugin index.
Installing plugin: krew
Installed plugin: krew
\
| Use this plugin:
| kubectl krew
| Documentation:
| https://krew.sigs.k8s.io/
| Caveats:
| \
| | krew is now installed! To start using kubectl plugins, you need to add
| | krew's installation directory to your PATH:
| |
| | * macOS/Linux:
| | - Add the following to your ~/.bashrc or ~/.zshrc:
| | export PATH="${KREW_ROOT:-$HOME/.krew}/bin:$PATH"
| | - Restart your shell.
| |
| | * Windows: Add %USERPROFILE%\.krew\bin to your PATH environment variable
| |
| | To list krew commands and to get help, run:
| | $ kubectl krew
| | For a full list of available plugins, run:
| | $ kubectl krew search
| |
| | You can find documentation at
| | https://krew.sigs.k8s.io/docs/user-guide/quickstart/.
| /
/
$ export PATH="${KREW_ROOT:-$HOME/.krew}/bin:$PATH"
$ echo $PATH
/root/.krew/bin:....
$ ls -l /root/.krew/bin
total 0
lrwxrwxrwx. 1 root root 34 Nov 13 10:15 kubectl-krew -> /root/.krew/store/krew/v0.4.4/krew
$ oc krew version
OPTION VALUE
GitTag v0.4.4
GitCommit 343e657
IndexURI https://github.com/kubernetes-sigs/krew-index.git
BasePath /root/.krew
IndexPath /root/.krew/index/default
InstallPath /root/.krew/store
BinPath /root/.krew/bin
DetectedPlatform linux/amd64
$ oc krew list
PLUGIN VERSION
krew v0.4.4
$ oc krew --help
krew is the kubectl plugin manager.
You can invoke krew through kubectl: "kubectl krew [command]..."
Usage:
kubectl krew [command]
Available Commands:
help Help about any command
index Manage custom plugin indexes
info Show information about an available plugin
install Install kubectl plugins
list List installed kubectl plugins
search Discover kubectl plugins
uninstall Uninstall plugins
update Update the local copy of the plugin index
upgrade Upgrade installed plugins to newer versions
version Show krew version and diagnostics
Flags:
-h, --help help for krew
-v, --v Level number for the log level verbosity
Use "kubectl krew [command] --help" for more information about a command.
Search plugin
oc krew search で plugin を検索する事ができます。
$ oc krew search
NAME DESCRIPTION INSTALLED
～中略～
validate Validation of resources for native Kubernetes t... no
vela Easily interact with KubeVela no
view-allocations List allocations per resources, nodes, pods. no
view-cert View certificate information stored in secrets no
view-quotas List resource quotas in colors no
view-secret Decode Kubernetes secrets no
view-serviceaccount-kubeconfig Show a kubeconfig setting to access the apiserv... no
view-utilization Shows cluster cpu and memory utilization no
view-webhook Visualize your webhook configurations no
viewnode Displays nodes with their pods and containers a... no
virt Control KubeVirt virtual machines using virtctl no
volsync Manage replication with the VolSync operator no
vpa-recommendation Compare VPA recommendations to actual resources... no
wait-job Waits for a Job to complete or fail no
warp Sync and execute local files in Pod no
whisper-secret Create secrets with improved privacy no
who-can Shows who has RBAC permissions to access Kubern... no
whoami Show the subject that's currently authenticated... no
windows-debug Windows node access via kubectl no
同様に、以下の URL からも確認することが出来ます。
一例として view-utilization の内容を確認してみます。
$ oc krew info view-utilization
NAME: view-utilization
INDEX: default
URI: https://github.com/etopeter/kubectl-view-utilization/releases/download/v0.3.3/kubectl-view-utilization-v0.3.3.tar.gz
SHA256: bcdd9925d13ff3837f61336269f9d45e338ca14df2f8174120bd571217d99918
VERSION: v0.3.3
HOMEPAGE: https://github.com/etopeter/kubectl-view-utilization
DESCRIPTION:
This plugin shows cluster resource utilization based on cpu and memory. It collects pod requests and node available resources to calculate metrics.
CAVEATS:
\
| This plugin needs the following programs:
| * bash
| * awk (gawk,mawk,awk)
/
Install plugin
oc krew install で plugin をインストールしてみます。
$ oc krew install view-allocations
Updated the local copy of plugin index.
Installing plugin: view-allocations
Installed plugin: view-allocations
\
| Use this plugin:
| kubectl view-allocations
| Documentation:
| https://github.com/davidB/kubectl-view-allocations
/
WARNING: You installed plugin "view-allocations" from the krew-index plugin repository.
These plugins are not audited for security by the Krew maintainers.
Run them at your own risk.
インストール時に WARNING 表示される通り、セキュリティー上のリスクがある点には注意が必要です。
$ oc krew list
PLUGIN VERSION
krew v0.4.4
view-allocations v0.20.1
view-allocations plugin はリソースの状況を分かりやすく確認することが出来ます。
$ oc view-allocations --help
kubectl plugin to list allocations (cpu, memory, gpu,... X utilization, requested, limit, allocatable,...)
Usage: kubectl-view_allocations [OPTIONS]
Options:
--context <CONTEXT> The name of the kubeconfig context to use
-n, --namespace <NAMESPACE> Show only pods from this namespace
-l, --selector <SELECTOR> Show only resource match this label selector
-u, --utilization Force to retrieve utilization (for cpu and memory), require to have metrics-server https://github.com/kubernetes-sigs/metrics-server
-z, --show-zero Show lines with zero requested and zero limit and zero allocatable
--precheck pre-check access and refersh token on kubeconfig by running `kubectl cluster-info`
--accept-invalid-certs accept invalid certificats (dangerous)
-r, --resource-name <RESOURCE_NAME> Filter resources shown by name(s), by default all resources are listed
-g, --group-by <GROUP_BY> Group information hierarchically (default: -g resource -g node -g pod) [possible values: resource, node, pod, namespace]
-o, --output <OUTPUT> Output format [default: table] [possible values: table, csv]
-h, --help Print help
-V, --version Print version
https://github.com/davidB/kubectl-view-allocations
$ oc view-allocations -n openshift-image-registry
Resource Requested Limit Allocatable Free
cpu (0%) 180.0m __ 87.2 87.0
99.888.7.17 (0%) 10.0m __ 15.9 15.9
node-ca-h6l5t 10.0m __ __ __
99.888.7.4 (0%) 10.0m __ 7.9 7.9
node-ca-fp4mp 10.0m __ __ __
99.888.7.5 (0%) 10.0m __ 7.9 7.9
node-ca-lbgbm 10.0m __ __ __
99.888.7.6 (0%) 20.0m __ 7.9 7.9
cluster-image-registry-operator-588f48965-8mqfc 10.0m __ __ __
node-ca-cdrl6 10.0m __ __ __
33.444.666.4 (0%) 10.0m __ 15.9 15.9
node-ca-njqcw 10.0m __ __ __
33.444.666.5 (0%) 10.0m __ 15.9 15.9
node-ca-k478v 10.0m __ __ __
33.444.55.5 (1%) 110.0m __ 15.9 15.8
image-registry-86c77dbfc4-9zz48 100.0m __ __ __
node-ca-v2nfp 10.0m __ __ __
ephemeral-storage __ __ 878.4G __
99.888.7.17 __ __ 99.3G __
99.888.7.4 __ __ 99.3G __
99.888.7.5 __ __ 99.3G __
99.888.7.6 __ __ 99.3G __
33.444.666.4 __ __ 282.4G __
33.444.666.5 __ __ 99.3G __
33.444.55.5 __ __ 99.3G __
memory (0%) 376.0Mi __ 327.6Gi 327.2Gi
99.888.7.17 (0%) 10.0Mi __ 27.8Gi 27.8Gi
node-ca-h6l5t 10.0Mi __ __ __
99.888.7.4 (0%) 10.0Mi __ 57.4Gi 57.4Gi
node-ca-fp4mp 10.0Mi __ __ __
99.888.7.5 (0%) 10.0Mi __ 57.4Gi 57.4Gi
node-ca-lbgbm 10.0Mi __ __ __
99.888.7.6 (0%) 60.0Mi __ 57.4Gi 57.3Gi
cluster-image-registry-operator-588f48965-8mqfc 50.0Mi __ __ __
node-ca-cdrl6 10.0Mi __ __ __
33.444.666.4 (0%) 10.0Mi __ 72.2Gi 72.2Gi
node-ca-njqcw 10.0Mi __ __ __
33.444.666.5 (0%) 10.0Mi __ 27.8Gi 27.8Gi
node-ca-k478v 10.0Mi __ __ __
33.444.55.5 (1%) 266.0Mi __ 27.8Gi 27.5Gi
image-registry-86c77dbfc4-9zz48 256.0Mi __ __ __
node-ca-v2nfp 10.0Mi __ __ __
nvidia.com/gpu __ __ 1.0 __
33.444.666.4 __ __ 1.0 __
pods (1%) 9.0 (1%) 9.0 970.0 961.0
99.888.7.17 (1%) 1.0 (1%) 1.0 160.0 159.0
99.888.7.4 (1%) 1.0 (1%) 1.0 110.0 109.0
99.888.7.5 (1%) 1.0 (1%) 1.0 110.0 109.0
99.888.7.6 (2%) 2.0 (2%) 2.0 110.0 108.0
33.444.666.4 (1%) 1.0 (1%) 1.0 160.0 159.0
33.444.666.5 (1%) 1.0 (1%) 1.0 160.0 159.0
33.444.55.5 (1%) 2.0 (1%) 2.0 160.0 158.0
Create plugin
独自の plugin を作成することもできます。
ここでは、以下のような簡単な Bash Script を plugin として使用してみます。
$ cat sample.sh
#!/bin/bash -x
echo "$(basename $0)"
oc get pod -A | egrep -v "Running|Completed"
$ ./sample.sh
++ basename ./sample.sh
+ echo sample.sh
sample.sh
+ oc get pod -A
+ egrep -v 'Running|Completed'
NAMESPACE NAME READY STATUS RESTARTS AGE
test-namespace-001 test-pod-deployment-usecase01-0001-5cd65c899d-8n4rf 0/3 Pending 0 22d
PATH 環境変数スコープ内のいずれかの Directory に Bash Script を配置します。ここでは、/usr/local/bin を使用してみます。
ファイル名を kubectl- で始まるものに変更します。ファイル名の - と _ によって plugin の呼び出し方が変わる事を確認するために、以下の2ファイルを配置してみます。
$ ls -1 /usr/local/bin/kubectl-*
/usr/local/bin/kubectl-list-error-pod
/usr/local/bin/kubectl-list_error_pod
plugin の呼び出し方によって、Bash Script が異なる事が確認できます。
$ oc list-error-pod
++ basename /usr/local/bin/kubectl-list_error_pod
+ echo kubectl-list_error_pod
kubectl-list_error_pod
+ oc get pod -A
+ egrep -v 'Running|Completed'
NAMESPACE NAME READY STATUS RESTARTS AGE
test-namespace-001 test-pod-deployment-usecase01-0001-5cd65c899d-8n4rf 0/3 Pending 0 22d
$ oc list error pod
++ basename /usr/local/bin/kubectl-list-error-pod
+ echo kubectl-list-error-pod
kubectl-list-error-pod
+ oc get pod -A
+ egrep -v 'Running|Completed'
NAMESPACE NAME READY STATUS RESTARTS AGE
test-namespace-001 test-pod-deployment-usecase01-0001-5cd65c899d-8n4rf 0/3 Pending 0 22d
なお、これらの plugin は Krew plugin による管理を行っていないため、oc krew list には表示されません。管理を行う場合は、以下の作業が必要です。
同様のネーミング・ルールは oc コマンドでも使用されており、oc-mirror plugin も、これによって実装されています。
$ ls -1 /usr/local/bin/oc-*
/usr/local/bin/oc-kubectl_list_error_pod
/usr/local/bin/oc-mirror
$ oc kubectl-list-error-pod
++ basename /usr/local/bin/oc-kubectl_list_error_pod
+ echo oc-kubectl_list_error_pod
oc-kubectl_list_error_pod
+ oc get pod -A
+ egrep -v 'Running|Completed'
NAMESPACE NAME READY STATUS RESTARTS AGE
test-namespace-001 test-pod-deployment-usecase01-0001-5cd65c899d-8n4rf 0/3 Pending 0 22d
$ oc mirror version
Client Version: version.Info{Major:"", Minor:"", GitVersion:"4.16.0-202409032335.p0.g819f011.assembly.stream.el9-819f011", GitCommit:"819f0115e4be3f55ed7d4edae1c38035811771ae", GitTreeState:"clean", BuildDate:"2024-09-04T05:16:07Z", GoVersion:"go1.21.11 (Red Hat 1.21.11-1.module+el8.10.0+21986+2112108a) X:strictfipsruntime", Compiler:"gc", Platform:"linux/amd64"}
$ oc plugin list
The following compatible plugins are available:
/root/.krew/bin/kubectl-krew
/root/.krew/bin/kubectl-view_allocations
/usr/local/bin/kubectl-list-error-pod
/usr/local/bin/kubectl-list_error_pod
/usr/local/bin/oc-kubectl_list_error_pod
/usr/local/bin/oc-mirror