logging: Log to systemd journal directly

While capturing stdout and stderr and automatically logging that to system
logging daemon provides basic information, a lot of information lost in the
process.

This change logs to systemd journal directly so that rich information such as
code file, code function, code line, etc, can be captured in a structured way.
To avoid double logging, discard stdout and stderr in the systemd unit file.

Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

data/lib/systemd/system/plinth.service

@@ -16,7 +16,7 @@
 #
 
 [Unit]
-Description=Plinth Web Interface
+Description=FreedomBox Service (Plinth)
 Documentation=man:plinth(1)
 After=network.target
 
@@ -26,6 +26,8 @@ Restart=on-failure
 ExecReload=/bin/kill -HUP $MAINPID
 User=plinth
 Group=plinth
+StandardOutput=null
+StandardError=null
 
 [Install]
 WantedBy=multi-user.target

debian/control

@@ -38,6 +38,7 @@ Build-Depends: debhelper (>= 11~)
  , python3-setuptools-git
  , python3-yaml
  , xmlto
+Recommends: python3-systemd
 Standards-Version: 4.2.1
 Homepage: https://salsa.debian.org/freedombox-team/plinth
 Vcs-Git: https://salsa.debian.org/freedombox-team/plinth.git

plinth/__main__.py

@@ -176,6 +176,17 @@ def configure_django():
         }
     }
 
+    try:
+        importlib.import_module('systemd.journal')
+    except ModuleNotFoundError:
+        pass
+    else:
+        logging_configuration['handlers']['journal'] = {
+            'class': 'systemd.journal.JournalHandler'
+        }
+        logging_configuration['root']['handlers'].append('journal')
+
+
     templates = [
         {
             'BACKEND': 'django.template.backends.django.DjangoTemplates',