A Simple Kubernetes Context Switcher
Published on 21 Aug 2018 · Filed in Information · 542 words (estimated 3 minutes to read)I recently needed to find a simple way of switching between Kubernetes contexts. I already use powerline-go (here’s the GitHub repo), which allows me to display the Kubernetes context in the prompt so I always know which context is the active (current) context. However, switching between contexts using kubectl config set-context <name> isn’t the easiest approach; not to mention it requires merging multiple config files into a single file (which is itself a bit of a task). So, I set out to create a simple Kubernetes context switcher—and here’s the initial results of my efforts.
Before I go any further, I’d like to stress 2 important points. First, I’m not a programmer, so keep that in mind. Second, this is a simple Kubernetes context switcher—it’s not meant to address any and every possible use case out there, nor do I claim any sort of sophistication in the code.
With those disclaimers out of the way, allow me to introduce kcs: the simple Kubernetes context switcher. kcs is built on the idea that it’s easiest to manage Kubernetes contexts in their own files, rather than trying to merge config files. So, it makes the assumption that you’ll store your Kubernetes contexts in separate config files. To add a new context, just copy the config file into the ~/.kube directory (the directory kubectl uses by default).
Once you have your config files in the ~/.kube directory, then using kcs is a piece of cake:
- To select a particular context, just use
kcs <context-name>(where<context-name>will equal a filename in the~/.kubedirectory). If you’re using a prompt tool that shows the active Kubernetes context, you’ll see the newly-selected context in your prompt. - To list the available contexts, type
kcs list. You’ll get a space-delimited list of the available contexts (again, where a context is equivalent to a file in~/.kube). - To specify that you don’t want any active context, specify
kcs none.
Now, if you haven’t figured it out yet, there’s a giant problem with the admittedly very simplistic approach I’ve taken here—the name of the context inside a config file may not match the name of the file itself, and it’s the name of the context that most prompt tools (like powerline-go, for example) will use, not the filename itself. Clearly, this is a problem, and one that I hope to be able to programmatically address at some point, but for now the workaround is to simply edit the config file and make the context name match the filename.
kcs is written entirely in Bash, so it should run unmodified on most Linux distributions as well as macOS. (Maybe at some point as my Golang skills develop I’ll re-code it in Golang.) If you’d like to give kcs a try, feel free to grab it from my GitHub “scripts” repository. As I mentioned before, I’m not a programmer (yet), so feel free to submit pull requests for improvements to kcs that might improve error checking, performance, portability, etc.
In the meantime, I hope this small (and quite simple) utility is helpful to folks.
UPDATE: Within days of publishing this post, someone pointed me to ktx, which does pretty much the same thing (only better). I’ve completely abandoned kcs in favor of ktx.