debian: use shell script to load /etc/authentic2/authentic.conf in systemd service file (#44960)

debian/authentic2-manage

@@ -24,6 +24,7 @@ fi
 if [ -f /etc/authentic2/db.conf ]; then
     . /etc/authentic2/db.conf
 fi
+
 if [ -f /etc/authentic2/authentic.conf ]; then
     . /etc/authentic2/authentic.conf
 fi

debian/authentic2.install

@@ -2,3 +2,4 @@ debian/conf/authentic.conf            /etc/authentic2
 debian/authentic2-manage              /usr/bin
 debian/conf/nginx-example.conf        /usr/share/authentic2
 debian/debian_config.py               /usr/lib/authentic2
+debian/launch-authentic2.sh           /usr/lib/authentic2

debian/authentic2.service

@@ -10,7 +10,7 @@ User=authentic2
 Group=authentic2
 ExecStartPre=/usr/bin/authentic2-manage migrate --noinput
 ExecStartPre=/usr/bin/authentic2-manage collectstatic --noinput
-ExecStart=/usr/bin/gunicorn3 \
+ExecStart=/usr/lib/authentic2/launch-authentic2.sh \
           --bind unix:/run/%p/%p.sock \
           --worker-class=sync \
           --workers 5 \

debian/launch-authentic2.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+if [ -f /etc/default/authentic2 ]; then
+    . /etc/default/authentic2
+fi
+
+if [ -f /etc/authentic2/db.conf ]; then
+    . /etc/authentic2/db.conf
+fi
+
+if [ -f /etc/authentic2/authentic.conf ]; then
+    . /etc/authentic2/authentic.conf
+fi
+
+/usr/bin/gunicorn3 "$@"