Kubectl is a command line utility used to control and manage Kubernetes clusters and objects running it them. Kubectl enables you to create, modify and delete various Kubernetes resources such as Deployments, Pods, Services, switching contexts and even to access container shell.
We’ll start with the installation of kubectl then move ahead to the configurations required to be more efficient when managing Kubernetes clusters from the CLI with kubectl. Note that you should have a working Kubernetes cluster before using this guide. Check any of our guides below.
- Deploy Production Kubernetes Cluster with RKE
- How To Deploy Lightweight Kubernetes Cluster in 5 minutes with K3s
- Deploy Production Ready Kubernetes Cluster with Ansible & Kubespray
- How To run Local Kubernetes Cluster in Docker Containers
- How to setup 3 node Kubernetes Cluster on Ubuntu with Weave Net CNI
Install Kubectl on Linux and macOS
Through installation of Kubernetes cluster, you must have installed kubectl as a basic requirement. But this means you need to login to your Master node to run kubectl commands. You can install kubectl on your local Linux or macOS machine.
Install kubectl on Linux
curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl
chmod +x ./kubectl
sudo mv ./kubectl /usr/local/bin/kubectlConfirm your installation of kubectl.
$ kubectl version
Client Version: version.InfoMajor:"1", Minor:"24", GitVersion:"v1.24.3", GitCommit:"aef86a93758dc3cb2c658dd9657ab4ad4afc21cb", GitTreeState:"clean", BuildDate:"2022-07-13T14:30:46Z", GoVersion:"go1.18.3", Compiler:"gc", Platform:"linux/amd64"
Kustomize Version: v4.5.4
Server Version: version.InfoMajor:"1", Minor:"24", GitVersion:"v1.24.3", GitCommit:"aef86a93758dc3cb2c658dd9657ab4ad4afc21cb", GitTreeState:"clean", BuildDate:"2022-07-13T14:23:26Z", GoVersion:"go1.18.3", Compiler:"gc", Platform:"linux/amd64"Install kubectl on macOS
For macOS, run the following commands.
curl -LO "https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/darwin/amd64/kubectl"
chmod +x ./kubectl
sudo mv ./kubectl /usr/local/bin/kubectl
kubectl versionConfigure Kubectl
The kubectl tool looks for a file named config in the $HOME/.kube directory, but a separate file can be specified using --kubeconfig option. The kubeconfig files helps you to organize information about clusters, users, namespaces, and authentication mechanisms.
$ ls $HOME/.kube/config
/home/jmutai/.kube/configIn this configuration you need to set the following elements:
- clusters – To configure access to a cluster, you need to know the location of the cluster and have credentials to access it. In the cluster section, you’ll set certificate-authority-data, access URL and the name for your cluster.
- context: A context element is used to group access parameters under a convenient name. Each context in the configuration file should have hree parameters: cluster, namespace, and user.
- users: Specify used to access and its credentials.
For a single cluster, your configuration file will look similar to below.
cat .kube/config
apiVersion: v1
clusters:
- cluster:
certificate-authority-data: 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
server: https://127.0.0.1:6443
name: default
contexts:
- context:
cluster: default
user: default
name: default
current-context: default
kind: Config
preferences:
users:
- name: default
user:
password: 76dd75552cb14f3085445277a2091c6c
username: adminGet the Cluster URL, CA data, and user credentials then substitute in the file.
Kubectl configuration for multiple clusters
Below is a template configuration file for four Kubernetes clusters, namely:
- k8s-dev – context is k8s-dev, user is k8s-dev-admin.
- k8s-staging – context is k8s-staging, user is k8s-staging-admin.
- k8s-qa – context is k8s-qa, user is k8s-qa-admin.
- k8s-prod – context is k8s-prod, user is k8s-prod-admin.
Each cluster has a unique name, associated context and user.
apiVersion: v1
kind: Config
preferences:
clusters:
- cluster:
certificate-authority-data:
server:
name: k8s-dev
- cluster:
certificate-authority-data:
server:
name: k8s-staging
- cluster:
certificate-authority-data:
server:
name: k8s-qa
- cluster:
certificate-authority-data:
server:
name: k8s-prod
contexts:
- context:
cluster: k8s-dev
user: k8s-dev-admin
name: k8s-dev
- context:
cluster: k8s-staging
user: k8s-staging-admin
name: k8s-staging
- context:
cluster: k8s-qa
user: k8s-qa-admin
name: k8s-qa
- context:
cluster: k8s-prod
user: k8s-prod-admin
name: k8s-prod
users:
- name: k8s-dev-admin
user:
password:
username:
- name: k8s-staging-admin
user:
client-certificate-data:
client-key-data:
- name: k8s-qa-admin
user:
client-certificate-data:
client-key-data:
- name: k8s-prod-admin
user:
client-certificate-data:
client-key-data:Modify the template to fit your use case and paste the contents inside $HOME/.kube/config.
Switching between contexts with kubectl
View current contexts:
$ kubectl config get-contexts
CURRENT NAME CLUSTER AUTHINFO NAMESPACE
* k8s-dev k8s-dev k8s-dev-admin kube-system
k8s-staging k8s-staging k8s-staging-admin kube-system
k8s-qa k8s-qa k8s-qa-admin kube-system
k8s-prod k8s-prod k8s-prod-admin kube-systemTo switch to a different context, use:
$ kubectl config use-context k8s-prod
Switched to context "k8s-prod".
$ kubectl config use-context k8s-staging
Switched to context "k8s-staging".Test:
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
k3s-master01 Ready master 10d v1.22.2-k3s.2
k3s-worker01 Ready 9d v1.22.2-k3s.2
k3s-worker02 Ready 9d v1.22.2-k3s.2 Easy Context and Namespace switching with kubectx and kubens
kubectx helps you switch between clusters back and forth and and kubens helps you switch between Kubernetes namespaces smoothly:
Install kubectx and kubens
wget https://raw.githubusercontent.com/ahmetb/kubectx/master/kubectx
wget https://raw.githubusercontent.com/ahmetb/kubectx/master/kubens
chmod +x kubectx kubens
sudo mv kubens kubectx /usr/local/binUsage pages:
$ kubectx --help
USAGE:
kubectx : list the contexts
kubectx : switch to context
kubectx - : switch to the previous context
kubectx -c, --current : show the current context name
kubectx = : rename context to
kubectx =. : rename current-context to
kubectx -d [] : delete context ('.' for current-context)
(this command won't delete the user/cluster entry
that is used by the context)
$ kubens --help
USAGE:
kubens : list the namespaces in the current context
kubens : change the active namespace of current context
kubens - : switch to the previous namespace in this context
kubens -c, --current : show the current namespace
kubens -h,--help : show this message
Examples:
# Get all contexts
$ kubectx
k8s-dev
k8s-staging
k8s-qa
k8s-prod
# Switch to prod context
$ kubectx k8s-prod
# Get all namespaces in k8s-prod context
$ kubens
# Switch to a namespace
$ kubens See below gifs for demo:
I hope our guide was helpful in your journey to Kubernetes management with kubectl and other tools like kubectx and kubens.
