How to switch namespace in kubernetes

问题

Say, I have two namespaces k8s-app1 and k8s-app2

I can list all pods from specific namespace using the below command

kubectl get pods -n <namespace>

We need to append namespace to all commands to list objects from the respective namespaces. Is there a way to set specific namespace and list objects without including the namespace explicitly?

回答1:

I like my answers short, to the point and with references to official documentation:

Answer:

kubectl config set-context --current --namespace=my-namespace

From:

https://kubernetes.io/docs/reference/kubectl/cheatsheet/

# permanently save the namespace for all subsequent kubectl commands in that context.
kubectl config set-context --current --namespace=ggckad-s2

回答2:

There are a few options:

Switch namespace only using the kubectl commands::

kubectl config set-context --current --namespace=<namespace>

Or, Create a new context with namespace defined:

kubectl config set-context gce-dev --user=cluster-admin --namespace=dev
kubectl config use-context gce-dev

Or, Use addons, like kubectx & kubens, the below command will switch the context to kube-system:

$ kubens kube-system

Or, Another easy alternative that I like without installing third party tools, is using bash alias(linux).

$ alias kubens='kubectl config set-context --current --namespace '
$ alias kubectx='kubectl config use-context '

// Usage
$ kubens kube-system    //Switch to a different namespace
$ kubectx docker        //Switch to separate context

回答3:

I was able to switch namespace using the below steps

kubectl config set-context $(kubectl config current-context) --namespace=<namespace>
kubectl config view | grep namespace
kubectl get pods

This is how i have tested

# Create namespaces k8s-app1, k8s-app2 and k8s-app3
master $ kubectl create ns k8s-app1
namespace/k8s-app1 created
master $ kubectl create ns k8s-app2
namespace/k8s-app2 created
master $ kubectl create ns k8s-app3
namespace/k8s-app3 created

# Create Service Account app1-sa in k8s-app1
# Service Account app2-sa in k8s-app2
# Service Account app3-sa in k8s-app3
master $ kubectl create sa app1-sa -n k8s-app1
serviceaccount/app1-sa created
master $ kubectl create sa app2-sa -n k8s-app2
serviceaccount/app2-sa created
master $ kubectl create sa app3-sa -n k8s-app3
serviceaccount/app3-sa created

# Switch namespace
master $ kubectl config set-context $(kubectl config current-context) --namespace=k8s-app1
Context "kubernetes-admin@kubernetes" modified.
master $ kubectl config view | grep namespace
    namespace: k8s-app1
master $ kubectl get sa
NAME      SECRETS   AGE
app1-sa   1         1m
default   1         6m
master $
master $ kubectl config set-context $(kubectl config current-context) --namespace=k8s-app2
Context "kubernetes-admin@kubernetes" modified.
master $ kubectl get sa
NAME      SECRETS   AGE
app2-sa   1         2m
default   1         7m
master $
master $ kubectl config set-context $(kubectl config current-context) --namespace=k8s-app3
Context "kubernetes-admin@kubernetes" modified.
master $ kubectl get sa
NAME      SECRETS   AGE
app3-sa   1         2m
default   1         7m

回答4:

You could use the following package called kubectx which make it very easy to switch between clusters using kubectx

and switching between namespaces using kubens

回答5:

I didn't like kubectx and kubens because they are adding one more letter for bash-complection to kubectl command.

So I just wrote tiny kubectl-use plugin:

# kubectl use prod
Switched to context "prod".

# kubectl use default
Switched to namespace "default".

# kubectl use stage kube-system
Switched to context "stage".
Switched to namespace "kube-system".

If you interesting to it, check https://github.com/kvaps/kubectl-use

回答6:

I created a function in .zshrc

ksns() { kubectl config set-context --current --namespace="$1" }

Then I call ksns default

回答7:

A Solution

npm install -g k8ss

k8ss switch --namespace=your_namespace
kubectl get pods

TLDR; Explanation as requested

There is a npm package called k8ss which stands for K8S Switching between clusters and namespaces.

The full usage is

k8ss switch --cluster=your_new_cluster --namespace=your_new_namespace

As in your case, you only need to switch namespace, so you can use the command without any configuration (as you already put a config file in the ~/.kube/config).

Advanced Usage

If you need to switch between different clusters then you need to put multiple config files in your home directory. In this case you can go to the package README to learn more.

来源：https://stackoverflow.com/questions/55373686/how-to-switch-namespace-in-kubernetes

标签

Kubernetes

namespaces