Update xds-server/xds-agent start-up doc

Change-Id: I3183073e1e84789ba3081d79f4f0721e67542311
Signed-off-by: Sebastien Douheret <sebastien.douheret@iot.bzh>

1 files changed, 44 insertions, 6 deletions

diff --git a/docs/part-2/2_xds-agent/2_start.md b/docs/part-2/2_xds-agent/2_start.md
index 8ff0b1d..7d6735d 100644
--- a/docs/part-2/2_xds-agent/2_start.md
+++ b/docs/part-2/2_xds-agent/2_start.md
@@ -1,14 +1,52 @@
 # Start-up
 
-Simply to start `xds-agent` executable
+## Start-up based on systemd user service
+
+For **Linux** distro, XDS agent can be started as a user service by Systemd.
+
+```bash
+/usr/lib/systemd/user/xds-agent.service
+```
+
+Use well-known systemd commands to control `xds-agent.service` service.
+
+```bash
+# Status XDS agent:
+systemctl --user status xds-agent
+
+# Start XDS agent
+systemctl --user start xds-agent
+
+# Stop XDS agent
+systemctl --user stop xds-agent
+```
+
+Default settings are defined in  `/etc/default/xds-agent` file but these
+settings you can overwritten by `$HOME/.xds/agent/agent-config.json` file,
+see [Configuration chapter](./1_config.html) for more details.
+
+## Manual start-up
+
+On **Linux or MacOS**, simply execute `xds-agent` executable:
 
 ```bash
-./xds-agent &
+/opt/AGL/bin/xds-agent
 ```
 
->**Note:**
->
->If need be, you can increase log level by setting option
+On **Windows**, simply execute `xds-agent` executable (root path may change
+depending where you installed/unzipped xds-agent tarball):
+
+```batch
+C:\AGL\bin\xds-agent.exe
+```
+
+<!-- note -->
+**Note:**
+
+If need be, you can increase log level by setting option
 `--log <level>`, supported *level* are: panic, fatal, error, warn, info, debug.
 
-You can now use XDS dashboard and check that connection with `xds-agent` is up.
+Invoke `xds-agent --help` to get more details about possible options that allow
+for example to change logging level or select a specific configuration file.
+
+<!-- endnote -->