我可以在 Kube.netes 中设置默认命名空间吗？

Question

Can I set the default namespace? That is:

$ kubectl get pods -n NAMESPACE

It saves me having to type it in each time especially when I'm on the one namespace for most of the day.

Answer 1

Yes, you can set the namespace as per the docs like so:

$ kubectl config set-context --current --namespace=NAMESPACE

Alternatively, you can use kubectx for this.

Answer 2

You can also use a temporary linux alias:

alias k='kubectl -n kube-system '

Then use it like

k get pods

That's it ;)

Answer 3

I used to use the aliases shown below and set the variable N to the namespace to use.

# Set N=-nNamespace  if N isn't set then no harm, no namespace will be used
alias k='kubectl $N'
alias kg='kubectl get $N'
alias ka='kubectl apply $N'
alias kl='kubectl logs $N'

To switch to the my-apps namespace; I'd use:

N=-nmy-apps

After this the commands:

kg pods

actually runs kubectl get -nmy-apps pods .

NOTE: If the bash variable N is not set, the command still works and runs as kubectl would by default.

To override the namespace set in N variable simply add the --namespace option like -nAnotherNamespace and the last namespace defined will be used.

Of course to more permanently (in the current shell) switch, I'd simply set the N variable as shown:

N=-nAnotherNamespace
kg pods

While the above works, I learned about kubens (bundled with kubectx , See github ) which works more permanently because it updates my $HOME/.kube/config file with a line that specifies the namespace to use for the current k8s cluster I'm using (dev in the example below)

contexts:
  - context:
        cluster: dev
        namespace: AnotherNamesapce  <<< THIS LINE IS ADDED by kubens
        user: user1
    name: dev
current-context: dev

But all kubeens does is what is already built into kubectl using:

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

So really a simple alias that is easier to type works just as well, so I picked ksn for (kubectl set namespace).

function ksn(){
  kubectl config set-context --current --namespace=$@
}

So now to switch context, I'm just using what is built into kubectl ! To switch to the namespace AnotherNamespace , I use:

ksn AnotherNamespace

Tada. The simplest "built in" solution.

Summary

For bash users, add the following to your $HOME/.bashrc file.

    function ksn(){
        if [ "$1" = "" ]
        then
            kubectl config view  -v6 2>&1 | grep 'Config loaded from file:' | sed -e 's/.*from file: /Config file:/'
            echo Current context: $(kubectl config current-context)
            echo Default namespace: $(kubectl config view --minify | grep namespace: | sed 's/.*namespace: *//')
        elif [ "$1" = "--unset" ]
        then
            kubectl config set-context --current --namespace=
        else
            kubectl config set-context --current --namespace=$1
        fi
    }

This lets you set a namespace, see what your namespace is or remove a default namespace (using --unset). See three commands below:

# Set namespace
ksn AnotherNamespace

# Display the selected namespace
ksn
Config file: /home/user/.kube/config
Current context: dev
Default namespace: AnotherNamespace

# Unset/remove a default namespace
ksn --unset

See also: https://kube.netes.io/docs/concepts/overview/working-with-objects/namespaces/ for the command to view the current namespace: