Krew is a kubectl command-line tool used to discover, manage and install kubectl plugins. It works in a similar way like yum, brew and apt. There are over 100 kubectl plugins supported by Krew.
For developers, you can use Krew to package and distribute your plugins on different platforms and make them available to users through a centralized repository.
In this post, we’ll cover how to install and use Krew to install kubectl plugins for your Kubernetes cluster. But you first need to have a running Kubernetes cluster with kubectl installed.
Krew can work across platforms, i.e, Windows, Linux and Mac and supports a v1.12 and above of kubectl. We shall cover installation on Linux, Mac and Windows.
Installation of krew
In this section we discuss krew installation steps on Linux, macOS and Windows systems.
Install krew on Linux/Mac
- Install Git
## macOS
$ brew install git
## Debian/Ubuntu
sudo apt install git-all
## RHEL/CentOS
sudo dnf install git-all2. Install Krew with the command below on your terminal:
(
set -x; cd "$(mktemp -d)" &&
curl -fsSLO "https://github.com/kubernetes-sigs/krew/releases/latest/download/krew.tar.gz" &&
tar zxvf krew.tar.gz &&
KREW=./krew-"$(uname | tr '[:upper:]' '[:lower:]')_$(uname -m | sed -e 's/x86_64/amd64/' -e 's/arm.*$/arm/')" &&
"$KREW" install krew
)
3. After a successful installation, you will see an output similar to the sample below:
......
Installing plugin: krew
Installed plugin: krew
\
| Use this plugin:
| kubectl krew
| Documentation:
| https://krew.sigs.k8s.io/
| Caveats:
| \
| | krew is now installed! To start using kubectl plugins, you need to add
| | krew's installation directory to your PATH:
| |
| | * macOS/Linux:
| | - Add the following to your ~/.bashrc or ~/.zshrc:
| | export PATH="$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/.
| /
/
4. Include $HOME/ .krew/bin to your PATH environment with the following command:
export PATH="$KREW_ROOT:-$HOME/.krew/bin:$PATH"Install krew on Windows
- Install Git
- Download git from here and install.
2. Download and install krew.exe here to a directory
3. Launch cmd as administrator and navigate to the directory you downloaded krew.exe
4. Install krew using the command below:
krew install krew5. Include %USERPROFILE%\.krew\bin dir to your PATH environment variable using the method on this link
How to Use Krew
Now that we have installed Krew, let us now explore how to use it.
Below are some of the commands that we will use to get started with Krew.
- To download Krew plugin list, which can be compared to updating repo cache using apt or yum:
$ kubectl krew update2. Discover available Krew plugins:
$ kubectl krew search
NAME DESCRIPTION INSTALLED
access-matrix Show an RBAC access matrix for server resources yes
advise-psp Suggests PodSecurityPolicies for cluster. no
allctx Run commands on contexts in your kubeconfig no
apparmor-manager Manage AppArmor profiles for cluster. no
auth-proxy Authentication proxy to a pod or service no
bd-xray Run Black Duck Image Scans no
bulk-action Do bulk actions on Kubernetes resources. no
ca-cert Print the PEM CA certificate of the current clu... no
capture Triggers a Sysdig capture to troubleshoot the r... no
cert-manager Manage cert-manager resources inside your cluster no
change-ns View or change the current namespace via kubectl. no
cilium Easily interact with Cilium agents. no
cluster-group Exec commands across a group of contexts. no
config-cleanup Automatically clean up your kubeconfig no
config-registry Switch between registered kubeconfigs no
creyaml Generate custom resource YAML manifest no
......3. Install plugin from Krew
$ kubectl krew install pod-logs
Updated the local copy of plugin index.
Installing plugin: pod-logs
Installed plugin: pod-logs
\
| Use this plugin:
| kubectl pod-logs
| Documentation:
| https://github.com/danisla/kubefunc
/
WARNING: You installed plugin "pod-logs" from the krew-index plugin repository.
These plugins are not audited for security by the Krew maintainers.
Run them at your own risk.
4. Use the plugin you have installed – you can now execute the plugin using kubectl
$ kubectl pod-logs
1) nginx-ingress-1605802027-controller-ch6ct default Running
2) dashboard-metrics-scraper-79c5968bdc-6p4fv kubernetes-dashboard Running
3) kubernetes-dashboard-665f4c5ff-bgrm2 kubernetes-dashboard Running
4) faas-idler-674fd4544c-tz72x openfaas Running
5) gateway-689746ff97-jqrst openfaas Running
6) nats-cdc589ff7-z8zf2 openfaas Running
Select a Pod: 1
I1119 16:09:26.542094 6 flags.go:205] Watching for Ingress class: nginx
-------------------------------------------------------------------------------
NGINX Ingress controller
Release: v0.34.1
Build: v20200715-ingress-nginx-2.11.0-8-gda5fa45e2
Repository: https://github.com/kubernetes/ingress-nginx
nginx version: nginx/1.19.1
-------------------------------------------------------------------------------
W1119 16:09:26.544149 6 flags.go:250] SSL certificate chain completion is disabled (--enable-ssl-chain-completion=false)
W1119 16:09:26.544237 6 client_config.go:552] Neither --kubeconfig nor --master was specified. Using the inClusterConfig. This might not work.
I1119 16:09:26.544553 6 main.go:231] Creating API client for https://10.96.0.1:443
I1119 16:09:26.554426 6 main.go:275] Running in Kubernetes cluster version v1.19 (v1.19.4) - git (clean) commit d360454c9bcd1634cf4cc52d1867af5491dc9c5f - platform linux/amd64
I1119 16:09:26.609756 6 main.go:87] Validated default/nginx-ingress-1605802027-default-backend as the default backend.
....5. To update plugins use the command below:
[email protected]:~# kubectl krew upgrade
Updated the local copy of plugin index.
Upgrading plugin: access-matrix
Skipping plugin access-matrix, it is already on the newest version
Upgrading plugin: krew
Skipping plugin krew, it is already on the newest version
Upgrading plugin: ns
Skipping plugin ns, it is already on the newest version
Upgrading plugin: pod-logs
Skipping plugin pod-logs, it is already on the newest version
6. List installed plugins
$ kubectl krew list
PLUGIN VERSION
access-matrix v0.4.5
krew v0.4.0
ns v0.9.1
pod-logs v1.0.17. To remove a plugin using Krew:
$ kubectl krew remove pod-logs
Uninstalled plugin pod-logsConclusion
Krew can be very handy for management of kubernetes clusters using kubectl. It makes is way easy to get packaged plugins in a centralized place.
Feel free to try to set it up on your cluster as it also has very simple steps.
