feat: fix the bug and add some feature in apisix.service (#143)

Author: saintak

usr/lib/systemd/system/apisix.service

@@ -1,11 +1,19 @@
+# apisix systemd service
+# https://github.com/api7/apisix-build-tools/blob/master/usr/lib/systemd/system/apisix.service
 [Unit]
 Description=apisix
-Conflicts=apisix.service
+#Conflicts=apisix.service
 After=network-online.target
+Wants=network-online.target
 
 [Service]
 Type=forking
+Restart=on-failure
 WorkingDirectory=/usr/local/apisix
 ExecStart=/usr/bin/apisix start
 ExecStop=/usr/bin/apisix stop
 ExecReload=/usr/bin/apisix reload
+LimitNOFILE=65536
+
+[Install]
+WantedBy=multi-user.target