Using unix domain sockets for docker syslog collector

client/driver/docker.go

@@ -238,7 +238,7 @@ func (d *DockerDriver) createContainer(ctx *ExecContext, task *structs.Task,
 		LogConfig: docker.LogConfig{
 			Type: "syslog",
 			Config: map[string]string{
-				"syslog-address": fmt.Sprintf("tcp://%v", syslogAddr),
+				"syslog-address": syslogAddr,
 			},
 		},
 	}

client/driver/logging/universal_collector.go

@@ -5,9 +5,12 @@ package logging
 import (
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"log/syslog"
 	"net"
+	"os"
+	"runtime"
 
 	"github.com/hashicorp/nomad/client/allocdir"
 	cstructs "github.com/hashicorp/nomad/client/driver/structs"
@@ -105,7 +108,8 @@ func (s *SyslogCollector) LaunchCollector(ctx *LogCollectorContext) (*SyslogColl
 	s.lre = lre
 
 	go s.collectLogs(lre, lro)
-	return &SyslogCollectorState{Addr: l.Addr().String()}, nil
+	syslogAddr := fmt.Sprintf("%s://%s", l.Addr().Network(), l.Addr().String())
+	return &SyslogCollectorState{Addr: syslogAddr}, nil
 }
 
 func (s *SyslogCollector) collectLogs(we io.Writer, wo io.Writer) {
@@ -160,6 +164,16 @@ func (s *SyslogCollector) configureTaskDir() error {
 // getFreePort returns a free port ready to be listened on between upper and
 // lower bounds
 func (s *SyslogCollector) getListener(lowerBound uint, upperBound uint) (net.Listener, error) {
+	if runtime.GOOS == "windows" {
+		return s.listenerTCP(lowerBound, upperBound)
+	}
+
+	return s.listenerUnix()
+}
+
+// listenerTCP creates a TCP listener using an unused port between an upper and
+// lower bound
+func (s *SyslogCollector) listenerTCP(lowerBound uint, upperBound uint) (net.Listener, error) {
 	for i := lowerBound; i <= upperBound; i++ {
 		addr, err := net.ResolveTCPAddr("tcp", fmt.Sprintf("localhost:%v", i))
 		if err != nil {
@@ -173,3 +187,21 @@ func (s *SyslogCollector) getListener(lowerBound uint, upperBound uint) (net.Lis
 	}
 	return nil, fmt.Errorf("No free port found")
 }
+
+// listenerUnix creates a Unix domain socket
+func (s *SyslogCollector) listenerUnix() (net.Listener, error) {
+	f, err := ioutil.TempFile("", "plugin")
+	if err != nil {
+		return nil, err
+	}
+	path := f.Name()
+
+	if err := f.Close(); err != nil {
+		return nil, err
+	}
+	if err := os.Remove(path); err != nil {
+		return nil, err
+	}
+
+	return net.Listen("unix", path)
+}

command/agent/agent.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"os"
 	"path/filepath"
+	"runtime"
 	"sync"
 	"time"
 
@@ -260,9 +261,11 @@ func (a *Agent) setupClient() error {
 		return fmt.Errorf("client setup failed: %v", err)
 	}
 
-	// Reserve some ports for the plugins
-	if err := a.reservePortsForClient(conf); err != nil {
-		return err
+	// Reserve some ports for the plugins if we are on Windows
+	if runtime.GOOS == "windows" {
+		if err := a.reservePortsForClient(conf); err != nil {
+			return err
+		}
 	}
 
 	// Create the client