Handling Kubeconfigs

By default, k3d will update your default kubeconfig with your new cluster’s details and set the current-context to it (can be disabled).
To get a kubeconfig set up for you to connect to a k3d cluster without this automatism, you can go different ways.

What is the default kubeconfig?

We determine the path of the used or default kubeconfig in two ways:

1. Using the KUBECONFIG environment variable, if it specifies exactly one file
2. Using the default path (e.g. on Linux it’s $HOME/.kube/config)

Getting the kubeconfig for a newly created cluster

1. Create a new kubeconfig file after cluster creation

   • k3d kubeconfig write mycluster
     • Note: this will create (or update) the file $HOME/.k3d/kubeconfig-mycluster.yaml
     • Tip: Use it: export KUBECONFIG=$(k3d kubeconfig write mycluster)
     • Note 2: alternatively you can use k3d kubeconfig get mycluster > some-file.yaml

2. Update your default kubeconfig upon cluster creation (DEFAULT)

   • k3d cluster create mycluster --kubeconfig-update-default
     • Note: this won’t switch the current-context (append --kubeconfig-switch-context to do so)

3. Update your default kubeconfig after cluster creation

   • k3d kubeconfig merge mycluster --kubeconfig-merge-default
     • Note: this won’t switch the current-context (append --kubeconfig-switch-context to do so)

4. Update a different kubeconfig after cluster creation

   • k3d kubeconfig merge mycluster --output some/other/file.yaml
     • Note: this won’t switch the current-context
   • The file will be created if it doesn’t exist

Switching the current context

None of the above options switch the current-context by default.
This is intended to be least intrusive, since the current-context has a global effect.
You can switch the current-context directly with the kubeconfig merge command by adding the --kubeconfig-switch-context flag.

Removing cluster details from the kubeconfig

k3d cluster delete mycluster will always remove the details for mycluster from the default kubeconfig. It will also delete the respective kubeconfig file in $HOME/.k3d/ if it exists.

Handling multiple clusters

k3d kubeconfig merge let’s you specify one or more clusters via arguments or all via --all.
All kubeconfigs will then be merged into a single file if --kubeconfig-merge-default or --output is specified.
If none of those two flags was specified, a new file will be created per cluster and the merged path (e.g. $HOME/.k3d/kubeconfig-cluster1.yaml:$HOME/.k3d/cluster2.yaml) will be returned.
Note, that with multiple cluster specified, the --kubeconfig-switch-context flag will change the current context to the cluster which was last in the list.

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Last update: June 9, 2021