HDDS-15954. Document ozone daemonlog command

hadoop-hdds/docs/content/tools/LogsInOzone.md

@@ -93,6 +93,37 @@ rootLogger.level = debug
 
 After saving the file and restarting the service, the service will start logging more detailed debug information.
 
+### Changing Service Log Levels at Runtime
+
+Use `ozone daemonlog` to inspect or change the log level of a running Ozone daemon without restarting it. The command talks to the daemon's HTTP endpoint and is useful when you need temporary debug logging while troubleshooting a live service.
+
+```bash
+ozone daemonlog -getlevel <host:port> <logger-name> [-protocol http|https]
+ozone daemonlog -setlevel <host:port> <logger-name> <level> [-protocol http|https]
+```
+
+The `<host:port>` value is the daemon HTTP address. For example, the default HTTP ports are `9874` for Ozone Manager, `9876` for Storage Container Manager, `9882` for Datanode, `19878` for the S3 Gateway web admin server, and `9888` for Recon.
+
+The following example checks the effective log level for the SCM event queue logger:
+
+```bash
+ozone daemonlog -getlevel scm.example.com:9876 org.apache.hadoop.hdds.server.events.EventQueue
+```
+
+To increase the same logger to `DEBUG`:
+
+```bash
+ozone daemonlog -setlevel scm.example.com:9876 org.apache.hadoop.hdds.server.events.EventQueue DEBUG
+```
+
+After collecting the required debug information, reset the logger to its previous level:
+
+```bash
+ozone daemonlog -setlevel scm.example.com:9876 org.apache.hadoop.hdds.server.events.EventQueue INFO
+```
+
+The change applies to the running daemon process. To make a log level change persistent across restarts, update the service's `log4j.properties` file instead.
+
 ### Enabling Debug Logs for CLI Tools
 
 To enable debug logging for Ozone CLI tools (e.g., `ozone sh volume create`), you can set the `OZONE_ROOT_LOGGER` environment variable to `debug`:

hadoop-hdds/docs/content/tools/_index.md

@@ -53,6 +53,7 @@ Admin commands:
    * **admin** -  Collects admin and developer related commands related to the 
    ozone components.
    * **insight** - Generic tool to display filtered log, metrics or configs to help debuging. See [the observability]({{< ref "feature/Observability.md" >}}) page for more information.
+   * **daemonlog** - Gets or sets the runtime log level of Ozone daemon loggers through their HTTP endpoints.
    * **classpath** - Prints the class path needed to get the hadoop jar and the
     required libraries.
    * **dtutil**    - Operations related to delegation tokens
@@ -65,4 +66,4 @@ Test tools:
 
    * **freon** -  Runs the ozone load generator.
 
- For more information see the following subpages:
+ For more information see the following subpages: