Fix error message on firewalld init

If firewalld is not installed (or I suppose not running), firewalld was
producing an error in the daemon init logs, even though firewalld is not
required for iptables stuff to function.
The firewalld library code was also logging directly to logrus instead
of returning errors.

Moved logging code higher up in the stack and changed firewalld code to
return errors where appropriate.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

daemon/networkdriver/bridge/driver.go

@@ -232,7 +232,9 @@ func InitDriver(config *Config) error {
 	}
 
 	if config.EnableIptables {
-		iptables.FirewalldInit()
+		if err := iptables.FirewalldInit(); err != nil {
+			logrus.Debugf("Error initializing firewalld: %v", err)
+		}
 	}
 
 	// Configure iptables for link support

pkg/iptables/firewalld.go

@@ -33,19 +33,18 @@ var (
 	onReloaded       []*func() // callbacks when Firewalld has been reloaded
 )
 
-func FirewalldInit() {
+func FirewalldInit() error {
 	var err error
 
-	connection, err = newConnection()
-
-	if err != nil {
-		logrus.Errorf("Failed to connect to D-Bus system bus: %s", err)
+	if connection, err = newConnection(); err != nil {
+		return fmt.Errorf("Failed to connect to D-Bus system bus: %v", err)
 	}
 	if connection != nil {
 		go signalHandler()
 	}
 
 	firewalldRunning = checkRunning()
+	return nil
 }
 
 // New() establishes a connection to the system bus.
@@ -146,19 +145,15 @@ func checkRunning() bool {
 		logrus.Infof("Firewalld running: %t", err == nil)
 		return err == nil
 	}
-	logrus.Info("Firewalld not running")
 	return false
 }
 
 // Firewalld's passthrough method simply passes args through to iptables/ip6tables
 func Passthrough(ipv IPV, args ...string) ([]byte, error) {
 	var output string
-
 	logrus.Debugf("Firewalld passthrough: %s, %s", ipv, args)
-	err := connection.sysobj.Call(dbusInterface+".direct.passthrough", 0, ipv, args).Store(&output)
-	if output != "" {
-		logrus.Debugf("passthrough output: %s", output)
+	if err := connection.sysobj.Call(dbusInterface+".direct.passthrough", 0, ipv, args).Store(&output); err != nil {
+		return nil, err
 	}
-
-	return []byte(output), err
+	return []byte(output), nil
 }

pkg/iptables/firewalld_test.go

@@ -7,7 +7,12 @@ import (
 )
 
 func TestFirewalldInit(t *testing.T) {
-	FirewalldInit()
+	if !checkRunning() {
+		t.Skip("firewalld is not running")
+	}
+	if err := FirewalldInit(); err != nil {
+		t.Fatal(err)
+	}
 }
 
 func TestReloaded(t *testing.T) {