Add Kubernetes segment w/ kele.el (#715)

* Add Kubernetes segment w/ kele.el

This PR adds a segment for displaying the currently active Kubectl context and,
optionally, the selected default namespace. It sources this information via
[`kele.el`](https://github.com/jinnovation/kele.el), which handles config
loading and refreshing.

In future iterations, we can add a local map to allow users to perform basic
Kubernetes management tasks via cursor, e.g. switching contexts/namespaces,
starting/stopping proxy servers, etc.

README.md

@@ -47,6 +47,7 @@ The `doom-modeline` was designed for minimalism, and offers:
 - An indicator for current input method
 - An indicator for debug state
 - An indicator for remote host
+- An indicator for Kubernetes state with [`kele.el`](https://github.com/jinnovation/kele.el)
 - An indicator for LSP state with `lsp-mode` or `eglot`
 - An indicator for GitHub notifications
 - An indicator for unread emails with `mu4e-alert` and `gnus`

doom-modeline-core.el

@@ -678,6 +678,11 @@ If nil, display only if the mode line is active."
   :type 'function
   :group 'doom-modeline)
 
+(defcustom doom-modeline-k8s-show-namespace t
+  "Whether to show the current Kubernetes context's default namespace."
+  :type 'boolean
+  :group 'doom-modeline)
+
 
 ;;
 ;; Faces

doom-modeline-segments.el

@@ -195,6 +195,8 @@
 (declare-function image-get-display-property "image-mode")
 (declare-function jsonrpc--request-continuations "ext:jsonrpc" t t)
 (declare-function jsonrpc-last-error "ext:jsonrpc" t t)
+(declare-function kele-current-context-name "ext:kele")
+(declare-function kele-current-namespace "ext:kele")
 (declare-function lsp--workspace-print "ext:lsp-mode")
 (declare-function lsp-describe-session "ext:lsp-mode")
 (declare-function lsp-workspace-folders-open "ext:lsp-mode")
@@ -3166,6 +3168,31 @@ Otherwise, it displays the message like `message' would."
           (force-mode-line-update)))
     (apply #'message format-string args)))
 
+;;
+;; Kubernetes
+;;
+
+(doom-modeline-def-segment k8s
+  (when (and (bound-and-true-p kele-mode) (doom-modeline--active))
+    (let* ((ctx (kele-current-context-name :wait nil))
+           (ns (kele-current-namespace :wait nil))
+           (icon (doom-modeline-icon 'mdicon "nf-md-kubernetes" "K8s:" "K8s:"))
+           (help-msg (let ((msgs (list (format "Current context: %s" ctx))))
+                       (when ns
+                         (setq msgs (append msgs (list (format "Current namespace: %s" ns)))))
+                       (string-join msgs "\n"))))
+      (propertize (concat
+                   icon
+                   (doom-modeline-spc)
+                   ctx
+                   (when (and doom-modeline-k8s-show-namespace ns) (format "(%s)" ns))
+                   (doom-modeline-spc))
+                  'local-map (let ((map (make-sparse-keymap)))
+                               (define-key map [mode-line down-mouse-1] kele-menu-map)
+                               map)
+                  'mouse-face 'doom-modeline-highlight
+                  'help-echo help-msg))))
+
 (provide 'doom-modeline-segments)
 
 ;;; doom-modeline-segments.el ends here