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?
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
There are a few options:
kubectl config set-context --current --namespace=<namespace>
kubectl config set-context gce-dev --user=cluster-admin --namespace=dev
kubectl config use-context gce-dev
kube-system:$ kubens kube-system
$ 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
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
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
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
I created a function in .zshrc
ksns() { kubectl config set-context --current --namespace="$1" }
Then I call ksns default
Check out https://krew.sigs.k8s.io/ They have plenty of plugins for different use cases.
For installation https://krew.sigs.k8s.io/docs/user-guide/setup/install/
kubectl krew install kubens
then after running the following command will set the current context for you
kubens <namespace>
kubectx - for swtiching contexts/clusters. Can be installed with "brew install kubectx"
kubens- for switching between namespaces in a cluster. Can also be installed with "brew install kubens"
kubie can switch context and namespaces. if you have fzf installed, the experience will be greatly improved.
kubie ctx show the list of available contexts (if fzf is installed, display a selectable menu of contexts)kubie ctx <context> switch the current shell to the given context (spawns a shell if not a kubie shell)kubie ctx - switch back to the previous contextkubie ctx <context> -r spawn a recursive shell in the given contextkubie ctx <context> -n <namespace> spawn a shell in the given context and namespacekubie ns show the list of available namespaces (if fzf is installed, display a selectable menu of namespaces)kubie ns <namespace> switch the current shell to the given namespacekubie ns - switch back to the previous namespacekubie ns <namespace> -r spawn a recursive shell in the given namespace
A kubectl replacement maintained by Red Hat for their OCP / OKD will get this done with less typing (as many other things).
So after downloading oc Client Tools from Github (link), change namespace (yes, in a standard k8s cluster, not just in OKD) by typing:
oc project <my_ns>
And to validate:
oc project
Note that project and namespace are not fully interchangeable, so in a k8s cluster you cannot list all projects by oc get projects (this works only in OKD/OCP), you need this command to list all namespaces:
oc get ns
npm install -g k8ss
k8ss switch --namespace=your_namespace
kubectl get pods
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).
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.
