Once you start managing more than one Kubernetes cluster, you'll start to demand more from your . Early on in my career spinning pods, I kept a separate file for each cluster, and wrote a small shell function to set the requisite environment variables. To switch between clusters was as simple as: $KUBECONFIG .kubeconfig →  k is buffalo-lab buffalo-lab
  (config): jhunt buffalo-lab kubernetes: /Users/ /.k/ I did this because the "correct" command was too much to remember: kubectl use-context buffalo-lab config See what I mean? Then I met kubectx and kubens, and they quickly became invaluable. Now I've got this directory full of all these disparate, discrete configuration files, and I don't want to hand-edit them back together. Thankfully, itself can merge them for us! kubectl will only merge configuration files if you specify them via the environment variable. You use the command-line flag, it won't work. Note: kubectl $KUBECONFIG cannot --kubeconfig To demonstrate this, I'm going to show you my directory: ~/.k $ ls -l ~/.k
total -rw-r--r-- jhunt staff Jan : buffalo-lab
-rw-r--r-- jhunt staff Jan : jhunt-vcp-prodernetes.yml
-rw-r--r-- jhunt staff Jan : jhunt-vcp-tinynetes
-rw-rw-rw- jhunt staff Jan : lke-eval1
-rw-r--r-- jhunt staff Jan : merged
-rw------- jhunt staff Nov : minikube
-rw-r--r-- jhunt staff Jan : oss
-rw-r--r-- jhunt staff Jan : tmp 96 1 7050 6 09 56 1 5641 1 11 30 1 5633 1 11 30 1 5481 3 12 32 1 23633 1 11 56 1 422 17 14 25 1 7023 1 11 30 1 25706 3 12 40 Using commands, we can see that each of them is different: kubectl config get-contexts $ =~/.k/buffalo-lab \
kubectl get-contexts
CURRENT   NAME              CLUSTER           AUTHINFO   NAMESPACE
*         buffalo-lab-k8s   buffalo-lab-k8s   admin $ =~/.k/lke-eval1 \
kubectl get-contexts
CURRENT   NAME                          CLUSTER      AUTHINFO           NAMESPACE
*         kubernetes-admin@kubernetes   kubernetes   kubernetes-admin   k8s-cp-ubuntu KUBECONFIG config default KUBECONFIG config If you put two (or more) files, separated by colons, in , then will merge them together semantically, and operate on the composite configuration. Any changes you make, like changing namespaces or setting contexts, will update the appropriate member file(s). $KUBECONFIG kubectl $ =~/.k/buffalo-lab:~/.k/lke-eval1 \
kubectl get-contexts
CURRENT   NAME                          CLUSTER           AUTHINFO           NAMESPACE
*         buffalo-lab-k8s               buffalo-lab-k8s   admin kubernetes-admin@kubernetes   kubernetes        kubernetes-admin   k8s-cp-ubuntu KUBECONFIG config default To write a new, aggregate configuration that contains the results of the merge, we can use . The flag prevents from redacting user secrets, certificates, and keys. To save this combined file, we can employ some shell redirection, along with a bit of caution. kubectl config view --raw --raw kubectl Every UNIX shell I've ever used truncates files that are the target of -style output redirection, the command producing the output gets executed. It's the nature of UNIX pipelines. We have to be careful with the order of our operations. > before This will fail spectacularly (and most assuredly destroy data in the process!): $ =a:b:c kubectl view --raw > a # DON'T RUN THIS! KUBECONFIG config The configuration file will be empty by the time gets around to trying to merge it in with the other two. Instead, use a temporary file and a rename operation: a kubectl $ =tmp:a:b:c kubectl view --raw > tmp \
    && mv tmp a KUBECONFIG config While you are merging all of these configurations together, you can also embed any referenced, external files (like certificates and private keys) by swapping out the flag for . This produces "portable" kubeconfigs, which do not have any dependencies on other parts of your filesystem. They can be moved, or copied, without losing their utility. Pro Tip: --raw --flatten Also published here .

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Kubernetes Tutorial: Merge all the Kubeconfigs! [Part 7]

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James Hunt

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