Supports datagram socket activation

cmd/circologd/activation.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"net"
+
+	"github.com/coreos/go-systemd/activation"
+)
+
+func Listeners() ([]net.Listener, error) {
+	files := activation.Files(false)
+	listeners := make([]net.Listener, len(files))
+
+	for i, f := range files {
+		if pc, err := net.FileListener(f); err == nil {
+			listeners[i] = pc
+			f.Close()
+		}
+	}
+	return listeners, nil
+}
+
+// PacketConns returns a slice containing a net.PacketConn for each matching socket type
+// passed to this process.
+//
+// The order of the file descriptors is preserved in the returned slice.
+// Nil values are used to fill any gaps. For example if systemd were to return file descriptors
+// corresponding with "udp, tcp, udp", then the slice would contain {net.PacketConn, nil, net.PacketConn}
+func PacketConns() ([]net.PacketConn, error) {
+	files := activation.Files(false)
+	conns := make([]net.PacketConn, len(files))
+
+	for i, f := range files {
+		if pc, err := net.FilePacketConn(f); err == nil {
+			conns[i] = pc
+			f.Close()
+		}
+	}
+	return conns, nil
+}

cmd/circologd/main.go

@@ -59,7 +59,13 @@ func main() {
 	server.SetHandler(handler)
 	if syslogSocket.isSocketActivated {
 		fmt.Printf("Binding to socket `%s` [syslog]\n", syslogSocket.String())
-		server.Listen(syslogSocket.Listener)
+		if syslogSocket.Listener != nil {
+			fmt.Println("(stream)")
+			server.Listen(syslogSocket.Listener)
+		} else {
+			fmt.Println("(datagram)", syslogSocket.Conn)
+			server.ListenDgram(syslogSocket.Conn)
+		}
 	} else {
 		syslogSocketPath := syslogSocket.Path
 		if syslogSocketPath != "" {

cmd/circologd/sockets.go

@@ -2,30 +2,26 @@ package main
 
 import (
 	"net"
-
-	"github.com/coreos/go-systemd/activation"
 )
 
 // SyslogSocket is a struct eventually containing a net.Listener
 // ready with messages, and a Path in case the Listener is not present.
 type SyslogSocket struct {
 	Listener          net.Listener
+	Conn              net.PacketConn
 	Path              string
 	isSocketActivated bool
 }
 
+// Set from command-line
 func (s *SyslogSocket) Set(v string) error {
-	sock, err := s.getActivationSocket()
-	if err != nil {
-		return err
-	}
-	s.isSocketActivated = false
-	if sock != nil {
-		s.Listener = sock
+	err := s.getActivationSocket()
+	if err == nil && (s.Conn != nil || s.Listener != nil) {
 		s.isSocketActivated = true
-		return nil
 	}
-	s.Path = v
+	if !s.isSocketActivated {
+		s.Path = v
+	}
 	return nil
 }
 
@@ -36,13 +32,19 @@ func (s *SyslogSocket) String() string {
 	return s.Path
 }
 
-func (s *SyslogSocket) getActivationSocket() (net.Listener, error) {
-	listeners, err := activation.Listeners()
+func (s *SyslogSocket) getActivationSocket() error {
+	conns, err := PacketConns()
+	if err == nil && len(conns) > 0 && conns[0] != nil {
+		s.Conn = conns[0]
+		return nil
+	}
+	listeners, err := Listeners()
 	if err != nil {
-		return nil, err
+		return err
 	}
 	if len(listeners) == 0 {
-		return nil, nil
+		return nil
 	}
-	return listeners[0], nil
+	s.Listener = listeners[0]
+	return nil
 }

vendor/gopkg.in/mcuadros/go-syslog.v2

@@ -1 +1 @@
-Subproject commit 60a4bd305d7f4271670e66a1cd9c67cc361186b6
+Subproject commit 166aad3f993ce4a67bf486e62d637c834c8a8fe6