# fun with kubectl and local current-context
I use kubectl on a daily basis and it’s a great tool.
However, something that has always bothered me is that setting a current context updates its configuration file and thus
for all terminal sessions. This can be surprising if you’re like me and switch between different contexts and terminal
sessions as running a command in shell A, then switching context in shell B and running a command, the context in shell A
will have changed!
I’ve previously looked at something like kubie but it doesn’t (currently) have
support for fish (yet), and my Rust is pretty bad at the moment, although adding support
for fish is probably a good way to improve that.
One possible solution would be to use multiple different configuration files, and set the KUBECONFIG environment
variable accordingly. My main issue with that is that credentials (such as refresh token(s) from OIDC/OAuth2) are
automatically refreshed and persisted to the configuration file, thus rendering all of the other configuration files out
of date and using a different one (eventually) causes another refresh and so on and so forth.
A simple trick that I’ve found to work around this is to have a “main” configuration file that holds clusters, contexts,
users, etc but that does not set the current-context, and then have multiple “context” configuration files that only
set the current-context and that are read-only. This has the nice side-effect that it’s no longer possible to set
the current-context (as shown below), but updated credentials is persisted to the main configuration file
automatically!
$ kubectl config current-context
test5
$ kubectl config set current-context test6
error: open /home/dist/.config/kubectx/test5: permission denied
Whether this is intended behaviour or not I’m not sure, but it works wonderfully well. I’ve combined this into a fish
function which also overrides Ctrl+D to “exit” from the current context:
# kubectx.fish
function kubectx --argument-names context
if test -n $context
set --local kubectx_config $XDG_CONFIG_HOME/kubectx/$context
set --global --export KUBECTX $context
set --global --export KUBECONFIG $kubectx_config:$HOME/.kube/config
if not test -f $kubectx_config
sed -e "s/%CONTEXT%/$context/g" $XDG_CONFIG_HOME/kubectx/template > $kubectx_config
chmod 400 $kubectx_config
end
bind -M insert \cd __kubectx_exit
bind \cd __kubexit_exit
bind -M visual \cd __kubexit_exit
commandline --function repaint
else
echo "<context> must not be empty" >&2
return 1
end
end
function __kubectx_exit
set --erase KUBECTX
set --erase KUBECONFIG
bind --erase -M insert \cd
bind --erase \cd
bind --erase -M visual \cd
commandline --function repaint
end
# $XDG_CONFIG_HOME/kubectx/template
apiVersion: v1
kind: Config
current-context: "%CONTEXT%"
I then use this together with fzf to more easily switch between contexts:
# __k8s_cluster_search.fish
function __k8s_cluster_search --description 'k8s cluster search'
set --local selected (kubectl config get-contexts --output name | eval (__fzfcmd) $FZF_DEFAULT_OPTS)
if string length -q -- $selected
kubectx $selected
end
end
Latest version of the above can also be found in my dotfiles repository.