Introduce cider-start-server command (#3555)

Author: behrica

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## master (unreleased)
 
+### New Features
+
+- Introduce `cider-start-nrepl-server` which does the same as `cider-jack-in` but without trying to connect to the started 
+nREPL server.
+
 ### Changes
 
 - Bump the injected `cider-nrepl` to [0.42.1](https://github.com/clojure-emacs/cider-nrepl/blob/v0.42.1/CHANGELOG.md#0421-2023-10-31).

cider.el

@@ -1302,12 +1302,15 @@ nil."
     (define-key map (kbd "j s") #'cider-jack-in-cljs)
     (define-key map (kbd "j m") #'cider-jack-in-clj&cljs)
     (define-key map (kbd "j u") #'cider-jack-in-universal)
+    (define-key map (kbd "j n") #'cider-start-nrepl-server)
     (define-key map (kbd "C-j j") #'cider-jack-in-clj)
     (define-key map (kbd "C-j s") #'cider-jack-in-cljs)
+    (define-key map (kbd "C-j n") #'cider-start-nrepl-server)
     (define-key map (kbd "C-j m") #'cider-jack-in-clj&cljs)
     (define-key map (kbd "C-j C-j") #'cider-jack-in-clj)
     (define-key map (kbd "C-j C-s") #'cider-jack-in-cljs)
     (define-key map (kbd "C-j C-m") #'cider-jack-in-clj&cljs)
+    (define-key map (kbd "C-j C-n") #'cider-start-nrepl-server)
     (define-key map (kbd "c j") #'cider-connect-clj)
     (define-key map (kbd "c s") #'cider-connect-cljs)
     (define-key map (kbd "c m") #'cider-connect-clj&cljs)
@@ -1326,24 +1329,49 @@ nil."
     map)
   "CIDER jack-in and connect keymap.")
 
+(defun cider--start-nrepl-server (params &optional on-port-callback)
+  "Starts an nrepl server and passes the callback to it.
+PARAMS is a plist optionally containing :project-dir and :jack-in-cmd.
+ON-PORT-CALLBACK is a function of one argument (server buffer)
+which is called by the process filter once the port of the connection has
+been determined.  Can be nil."
+  (nrepl-start-server-process
+   (plist-get params :project-dir)
+   (plist-get params :jack-in-cmd)
+   on-port-callback))
+
+
+(defun cider--update-params (params)
+  "Completes the passed in PARAMS from user input.
+Updates :project-dir, confirmation for existing session and :jack-in-cmd."
+  (thread-first
+    params
+    (cider--update-project-dir)
+    (cider--check-existing-session)
+    (cider--update-jack-in-cmd)))
+
 ;;;###autoload
 (defun cider-jack-in-clj (params)
   "Start an nREPL server for the current project and connect to it.
 PARAMS is a plist optionally containing :project-dir and :jack-in-cmd.
 With the prefix argument, allow editing of the jack in command; with a
 double prefix prompt for all these parameters."
   (interactive "P")
-  (let ((params (thread-first
-                  params
-                  (cider--update-project-dir)
-                  (cider--check-existing-session)
-                  (cider--update-jack-in-cmd))))
-    (nrepl-start-server-process
-     (plist-get params :project-dir)
-     (plist-get params :jack-in-cmd)
+  (let ((params (cider--update-params params)))
+    (cider--start-nrepl-server
+     params
      (lambda (server-buffer)
        (cider-connect-sibling-clj params server-buffer)))))
 
+
+(defun cider-start-nrepl-server (params)
+  "Start an nREPL server for the current project, but don't connect to it.
+PARAMS is a plist optionally containing :project-dir and :jack-in-cmd.
+With the prefix argument, allow editing of the start server in command; with a
+double prefix prompt for all these parameters."
+  (interactive "P")
+  (cider--start-nrepl-server (cider--update-params params)))
+
 ;;;###autoload
 (defun cider-jack-in-cljs (params)
   "Start an nREPL server for the current project and connect to it.

doc/modules/ROOT/pages/basics/up_and_running.adoc

@@ -267,6 +267,18 @@ Here is an example Nbb Jack-In command, providing a custom `:jack-in-cmd`.
   (cider-jack-in-clj '(:jack-in-cmd "nbb nrepl-server")))
 ----
 
+==== Starting nREPL server without trying to connect to it ====
+
+In some situations, it might be useful to only start a nREPL server process, without
+connecting to it. This can support complex setups
+for which CIDER cannot reliably detect to which server/port to connect, and
+would therefore fail.
+This assumes that the user will execute a `cider-connect` command manually afterwards,
+specifying host/port.
+
+For this scenario, the `cider-start-nrepl-server` kbd:[j n]  command is offered, which optionally
+takes the same parameters as `cider-jack-in`.
+
 
 == Connect to a Running nREPL Server