From 7c146772775f215e283cc106bd68b6b45a42ddec Mon Sep 17 00:00:00 2001
From: Sunil Mohan Adapa <sunil@medhas.org>
Date: Fri, 4 Apr 2025 15:39:02 -0700
Subject: [PATCH] service: Notify systemd when service starts up

- Run as a Type=notify service with systemd service.

- Notify systemd just before blocking in the main thread.

- This allows systemd to catch any errors with startup of the service and log
appropriately. This also allows clients depending on making DBus calls etc. to
know that service is ready to serve requests.

- This will increase the boot time slightly as systemd will wait until
FreedomBox service to become active.

Tests:

- Raise an exception in main() during startup. Run 'systemctl start plinth'. No
error is thrown without this patch. With the patch, an error is shown.

- After 'systemctl start plinth', service shows in 'active' state.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>
---
 data/usr/lib/systemd/system/plinth.service | 2 ++
 plinth/__main__.py                         | 8 ++++++++
 plinth/web_server.py                       | 4 ++++
 3 files changed, 14 insertions(+)

diff --git a/data/usr/lib/systemd/system/plinth.service b/data/usr/lib/systemd/system/plinth.service
index 15a9fd4ed..d84e62b13 100644
--- a/data/usr/lib/systemd/system/plinth.service
+++ b/data/usr/lib/systemd/system/plinth.service
@@ -7,6 +7,7 @@ After=network.target
 StartLimitIntervalSec=0
 
 [Service]
+Type=notify
 ExecStart=/usr/bin/plinth
 Restart=on-failure
 RestartSec=5
@@ -15,6 +16,7 @@ User=plinth
 Group=plinth
 StandardOutput=null
 StandardError=null
+NotifyAccess=main
 PrivateTmp=yes
 
 [Install]
diff --git a/plinth/__main__.py b/plinth/__main__.py
index fba9fea58..09d062ff2 100644
--- a/plinth/__main__.py
+++ b/plinth/__main__.py
@@ -6,6 +6,8 @@ import logging
 import sys
 import threading
 
+import systemd.daemon
+
 from . import __version__
 from . import app as app_module
 from . import (cfg, frontpage, glib, log, menu, module_loader, setup,
@@ -158,6 +160,12 @@ def main():
     web_server.init()
     web_server.run(on_web_server_stop)
 
+    # systemd will wait until notification to proceed with other processes. We
+    # have service Type=notify.
+    systemd.daemon.notify('READY=1')
+
+    web_server.block()
+
 
 if __name__ == '__main__':
     main()
diff --git a/plinth/web_server.py b/plinth/web_server.py
index 9020c8be4..09eb78bc8 100644
--- a/plinth/web_server.py
+++ b/plinth/web_server.py
@@ -122,6 +122,10 @@ def run(on_web_server_stop):
         cherrypy.engine.start()
 
     cherrypy.engine.subscribe('stop', on_web_server_stop)
+
+
+def block():
+    """Block the calling thread until web server exits."""
     cherrypy.engine.block()