Add lisp/net/tramp-kubernetes.elscratch/tramp-kubernetes

* lisp/net/tramp-kubernetes.el: New file.
* doc/misc/tramp.texi (Inline methods): Add kubernetes.
(Customizing Methods): Remove kubernetes-tramp.
* etc/NEWS: Mention new Tramp method "kubernetes".
* lisp/net/tramp-compat.el (kubernetes-tramp): Warn if that package is
used.

4 files changed, 115 insertions, 11 deletions

diff --git a/doc/misc/tramp.texi b/doc/misc/tramp.texi
index a182c0510d7..9e6de15f1f4 100644
--- a/doc/misc/tramp.texi
+++ b/doc/misc/tramp.texi
@@ -912,6 +912,14 @@ Integration for Docker containers.  A container is accessed via
 @samp{user} is the (optional) user that you want to use, and
 @samp{container} is the id or name of the container.
 
+@item @option{kubernetes}
+@cindex method @option{kubernetes}
+@cindex @option{kubernetes} method
+
+Integration for Kubernetes pod containers.  A container is accessed
+via @file{@trampfn{kubernetes,pod,/path/to/file}}, where @samp{pod} is
+the name of the pod.  Currently, the first container in a pod is used.
+
 @end table
 
 
@@ -1772,15 +1780,6 @@ They can be installed with Emacs's Package Manager.  This includes
 @c @item ibuffer-tramp.el
 @c Contact Svend Sorensen <svend@@ciffer.net>
 
-@item kubernetes-tramp
-@cindex method @option{kubectl}
-@cindex @option{kubectl} method
-Integration for Docker containers deployed in a Kubernetes cluster.  A
-container is accessed via
-@file{@trampfn{kubectl,user@@container,/path/to/file}}, @samp{user}
-and @samp{container} have the same meaning as with the @option{docker}
-method.
-
 @item lxc-tramp
 @cindex method @option{lxc}
 @cindex @option{lxc} method
diff --git a/etc/NEWS b/etc/NEWS
index d7bc4b0e0c2..6104e71ed44 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2409,8 +2409,8 @@ and friends.
 ** Tramp
 
 +++
-*** New connection method "docker".
-It allows accessing environments provided by Docker.
+*** New connection methods "docker" and "kubernetes".
+They allows accessing environments provided by Docker / Kubernetes.
 
 ---
 *** Tramp supports abbreviating remote home directories now.
diff --git a/lisp/net/tramp-compat.el b/lisp/net/tramp-compat.el
index f6cc1034ca5..c510626ecad 100644
--- a/lisp/net/tramp-compat.el
+++ b/lisp/net/tramp-compat.el
@@ -53,6 +53,9 @@
 (with-eval-after-load 'docker-tramp
   (warn (concat "Package `docker-tramp' has been obsoleted, "
                 "please use integrated package `tramp-docker'")))
+(with-eval-after-load 'kubernetes-tramp
+  (warn (concat "Package `kubernetes-tramp' has been obsoleted, "
+                "please use integrated package `tramp-kubernetes'")))
 
 ;; For not existing functions, obsolete functions, or functions with a
 ;; changed argument list, there are compiler warnings.  We want to
diff --git a/lisp/net/tramp-kubernetes.el b/lisp/net/tramp-kubernetes.el
new file mode 100644
index 00000000000..0ad333f8187
--- /dev/null
+++ b/lisp/net/tramp-kubernetes.el
@@ -0,0 +1,102 @@
+;;; tramp-kubernetes.el --- Tramp integration for Kubernetes containers  -*- lexical-binding: t; -*-
+
+;; Copyright © 2022 Free Software Foundation, Inc.
+
+;; Keywords: comm, processes, kubernetes
+;; Package: tramp
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; `tramp-kubernetes' allows Tramp access to environments provided by
+;; Kubernetes.
+;;
+;; The kubectl program should be configured correctly.  You may also
+;; want to set the namespace to use:
+;;
+;; kubectl config set-context --current --namespace=<my-namespace>
+;;
+;; ## Usage
+;;
+;; Open a file in container:
+;;
+;;     C-x C-f /kubernetes:POD:/path/to/file
+;;
+;; Where:
+;;     POD     is the pod to connect to.
+;;             By default, the first container in that pod will be
+;;             connected to.
+
+;;; Code:
+
+(require 'tramp)
+
+;;;###tramp-autoload
+(defcustom tramp-kubernetes-program "kubectl"
+  "Name of the Kubernetes client program."
+  :group 'tramp
+  :version "29.1"
+  :type '(choice (const "kubectl")
+                 (string)))
+
+;;;###tramp-autoload
+(defconst tramp-kubernetes-method "kubernetes"
+  "Tramp method name to use to connect to Kubernetes containers.")
+
+;;;###tramp-autoload
+(defun tramp-kubernetes--completion-function (&rest _args)
+  "List Kubernetes pods available for connection.
+
+This function is used by `tramp-set-completion-function', please
+see its function help for a description of the format."
+  (when-let ((raw-list (shell-command-to-string
+                        (concat tramp-kubernetes-program
+                                " get pods --no-headers "
+                                "-o custom-columns=NAME:.metadata.name")))
+             (names (split-string raw-list "\n" 'omit)))
+    (mapcar (lambda (name)
+              (list nil name))
+            names)))
+
+;;;###tramp-autoload
+(defvar tramp-default-remote-shell) ;; Silence byte compiler.
+
+;;;###tramp-autoload
+(tramp--with-startup
+ (push `(,tramp-kubernetes-method
+         (tramp-login-program ,tramp-kubernetes-program)
+         (tramp-login-args (("exec")
+                            ("%h")
+                            ("-it")
+                            ("--")
+                            ("%l")))
+         (tramp-remote-shell ,tramp-default-remote-shell)
+         (tramp-remote-shell-login ("-l"))
+         (tramp-remote-shell-args ("-i" "-c")))
+       tramp-methods)
+
+ (tramp-set-completion-function
+  tramp-kubernetes-method
+  '((tramp-kubernetes--completion-function ""))))
+
+(add-hook 'tramp-unload-hook
+          (lambda ()
+            (unload-feature 'tramp-kubernetes 'force)))
+
+(provide 'tramp-kubernetes)
+
+;;; tramp-kubernetes.el ends here