[RUN-3585] add alternative mode to start runner as service

docs/learning/howto/runner-service-windows.md

@@ -141,6 +141,10 @@ endlocal
 
 7. Execute the following command (you can copy and paste it directly on the CMD terminal to execute it):
 
+:::: tabs
+
+@tab Standard (`java` mode)
+
 ```bat
 runner.exe //IS//Runner ^
  --DisplayName=Runner ^
@@ -168,6 +172,43 @@ runner.exe //IS//Runner ^
 The service name uses a double slash (`//IS//runner`) — this is the procrun syntax for "install service". `--Jvm=auto` lets procrun locate `jvm.dll` automatically from `JAVA_HOME` / the registry. The stop is delegated to `stop-runner.bat` through `cmd.exe`; the full path to `cmd.exe` is required because procrun passes `--StopImage` directly to `CreateProcess`, which does not search the `PATH` (a bare `cmd` fails with `The system cannot find the file specified`).
 :::
 
+@tab Alternative More logging (`jvm` mode)
+
+With `--StartMode=java`, procrun launches the Runner as a **separate** `java.exe` process and does not pipe that process's output into `--StdOutput`/`--StdError`, so `runner.log` can stay empty. Use this `jvm`-mode variant instead: procrun loads the JVM **in-process** and captures the Runner's `System.out`/`System.err` directly into the log file.
+
+```bat
+runner.exe //IS//Runner ^
+ --DisplayName=Runner ^
+ --LogLevel=Info ^
+ --LogPath=C:\runner ^
+ --ServiceUser=LocalSystem ^
+ --Startup=auto ^
+ --Jvm="<JAVA_INSTALL_PATH>\bin\server\jvm.dll" ^
+ --StartMode=jvm ^
+ --Classpath=C:\runner\runner.jar ^
+ --StartClass=com.rundeck.runner.agent.RunnerApplication ^
+ --StartMethod=main ^
+ --StartPath=C:\runner ^
+ --StopMode=exe ^
+ --StopImage=C:\Windows\System32\cmd.exe ^
+ --StopParams=/c#C:\runner\stop-runner.bat ^
+ --StopPath=C:\runner ^
+ --StopTimeout=30 ^
+ --PidFile=runner.pid ^
+ --JvmMs=1024 ^
+ --JvmMx=4096 ^
+ --StdOutput=C:\runner\runner.log ^
+ --StdError=C:\runner\runner.log
+```
+
+:::warning Set `--Jvm` to your real `jvm.dll` path
+In `jvm` mode `--Jvm=auto` often fails with `no JVM configured or found in registry` (many JDK/JRE builds don't register in the Windows registry, and the `LocalSystem` account doesn't see a user-level `JAVA_HOME`). Replace `<JAVA_INSTALL_PATH>` with your Java installation directory (the same path as `JAVA_HOME`)
+
+Note that `jvm` mode replaces `--StartMode=java`/`--StartParams=-jar#runner.jar` with `--StartMode=jvm`, `--Classpath` (the path to `runner.jar`) and `--StartClass` (the Runner main class). The `runner.exe` (procrun) and the `jvm.dll` must be the **same architecture** (use the 64-bit `prunsrv.exe` from `amd64\` with a 64-bit JRE/JDK).
+:::
+
+::::
+
 You will see messages similar to the following:
 
 ```log