fix(server): require additional variable to enable systemd logging (#5222)

* fix(logging): require additional variable to enable systemd logging

* use a better name

cmd/svc.go

@@ -248,6 +248,7 @@ ExecStart={{.Path|cmdEscape}}{{range .Arguments}} {{.|cmd}}{{end}}
 TimeoutStopSec=20
 RestartSec=120
 EnvironmentFile=-/etc/sysconfig/{{.Name}}
+Environment="ND_SYSTEMD_PRIORITY_LOGGING=1"
 
 DevicePolicy=closed
 NoNewPrivileges=yes

conf/configuration.go

@@ -341,9 +341,11 @@ func Load(noConfigDump bool) {
 			os.Exit(1)
 		}
 		log.SetOutput(out)
-	} else if os.Getenv("JOURNAL_STREAM") != "" {
+	} else if os.Getenv("ND_SYSTEMD_PRIORITY_LOGGING") != "" && os.Getenv("JOURNAL_STREAM") != "" {
 		// When running under systemd, prepend syslog priority prefixes so
 		// journald assigns the correct severity to each log line.
+		// Note that we have an additional environment variable, as JOURNAL_STREAM
+		// can be present in a systemd environment even if not running as a systemd service
 		log.EnableJournalFormat()
 	}