Nikolay Grozev
Nikolay Grozev

Categories

Tags

Background

I often need to switch between Kubernetes clusters for different projects. Managing the kubectl configuration for each of them and their files can be cumbersome.

By default, the kubectl command line client uses the ~/.kube/config file to store the Kubernetes endpoint and credentials. If you use minikube or Docker Desktop’s local Kubernetes, you should be able to see their configurations in that file.

When you work with a cloud based Kubernetes instance, the cloud console will provide the configuration as a yml file. You then need to specify the file as the value of the environment variable KUBECONFIG, which is used by kubectl. This can quickly become cumbersome and hard to maintain.

Multiple Contexts

To solve this problem, I’ve started storing all cloud cluster configuration yml files in a new folder ~/.kube/custom-contexts/. Usually, I’d make a folder for each cloud Kube instance, which contains the yml config and other auxiliary files (e.g. pem certificates).

Here’s the content of my ~/.kube folder:

1
2
3
4
5
6
7
8
~/.kube/
 ├── cache
 │   └── ...
 ├── config
 └── custom-contexts
     └── NikTest-Kube-Config
         ├── ca-hou02-NikTest.pem
         └── kube-config-hou02-NikTest.yml

It has a single Kubernetes configuration in the NikTest-Kube-Config folder which contains the yml config and pem certificate downloaded from the IBM Cloud console.

Now we need to load all this configuration in the KUBECONFIG environment variable so that kubectl can switch between them. The following script does the trick:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
# Set the default kube context if present
DEFAULT_KUBE_CONTEXTS="$HOME/.kube/config"
if test -f "${DEFAULT_KUBE_CONTEXTS}"
then
  export KUBECONFIG="$DEFAULT_KUBE_CONTEXTS"
fi

# Additional contexts should be in ~/.kube/custom-contexts/ 
CUSTOM_KUBE_CONTEXTS="$HOME/.kube/custom-contexts"
mkdir -p "${CUSTOM_KUBE_CONTEXTS}"

OIFS="$IFS"
IFS=$'\n'
for contextFile in `find "${CUSTOM_KUBE_CONTEXTS}" -type f -name "*.yml"`  
do
    export KUBECONFIG="$contextFile:$KUBECONFIG"
done
IFS="$OIFS"

I put the above code snippet in my ~/.bashrc so that it loads on every new terminal session. This way, if I add or delete configuration files from ~/.kube/custom-contexts, this will be reflected in every subsequent terminal session.

Switching Between Contexts

Now we can list all preconfigured contexts and see which one is active:

1
2
3
4
5
6
kubectl config get-contexts

# CURRENT NAME           CLUSTER        AUTHINFO
#         NikTest        NikTest        <****>   
#         docker-desktop docker-desktop docker-desktop         
# *       minikube       minikube       minikube 

We can also get the name of the active context/cluster:

1
2
# Prints the current config nema - e.g. minikube
kubectl config current-context

Finally, we can switch between the predefined contexts:

1
2
# Switch to a context/cluster
kubectl config use-context NikTest