agent: syslog support. Fixes #105.

CHANGELOG.md

@@ -13,6 +13,7 @@ IMPROVEMENTS:
   * Fixing potential name conflicts on the WAN gossip ring [GH-158]
   * /v1/catalog/services returns an empty slice instead of null. [GH-145]
   * `members` command returns exit code 2 if no results. [GH-116]
+  * Enable logging to syslog. [GH-105]
 
 BUG FIXES:
 

command/agent/command.go

@@ -4,6 +4,7 @@ import (
 	"flag"
 	"fmt"
 	"github.com/armon/go-metrics"
+	"github.com/hashicorp/go-syslog"
 	"github.com/hashicorp/logutils"
 	"github.com/mitchellh/cli"
 	"io"
@@ -61,6 +62,8 @@ func (c *Command) readConfig() *Config {
 
 	cmdFlags.IntVar(&cmdConfig.Protocol, "protocol", -1, "protocol version")
 
+	cmdFlags.BoolVar(&cmdConfig.EnableSyslog, "syslog", false,
+		"enable logging to syslog facility")
 	cmdFlags.Var((*AppendSliceValue)(&cmdConfig.StartJoin), "join",
 		"address of agent to join on startup")
 
@@ -141,9 +144,25 @@ func (c *Command) setupLoggers(config *Config) (*GatedWriter, *logWriter, io.Wri
 		return nil, nil, nil
 	}
 
+	// Check if syslog is enabled
+	var syslog io.Writer
+	if config.EnableSyslog {
+		l, err := gsyslog.NewLogger(gsyslog.LOG_NOTICE, "consul")
+		if err != nil {
+			c.Ui.Error(fmt.Sprintf("Syslog setup failed: %v", err))
+			return nil, nil, nil
+		}
+		syslog = &SyslogWrapper{l}
+	}
+
 	// Create a log writer, and wrap a logOutput around it
 	logWriter := NewLogWriter(512)
-	logOutput := io.MultiWriter(c.logFilter, logWriter)
+	var logOutput io.Writer
+	if syslog != nil {
+		logOutput = io.MultiWriter(c.logFilter, logWriter, syslog)
+	} else {
+		logOutput = io.MultiWriter(c.logFilter, logWriter)
+	}
 	return logGate, logWriter, logOutput
 }
 
@@ -489,6 +508,7 @@ Options:
   -node=hostname           Name of this node. Must be unique in the cluster
   -protocol=N              Sets the protocol version. Defaults to latest.
   -server                  Switches agent to server mode.
+  -syslog                  Enables logging to syslog
   -ui-dir=path             Path to directory containing the Web UI resources
   -pid-file=path           Path to file to store agent PID
 

command/agent/config.go

@@ -131,6 +131,10 @@ type Config struct {
 	// PidFile is the file to store our PID in
 	PidFile string `mapstructure:"pid_file"`
 
+	// EnableSyslog is used to also tee all the logs over to syslog. Only supported
+	// on linux and OSX. Other platforms will generate an error.
+	EnableSyslog bool `mapstructure:"enable_syslog"`
+
 	// AEInterval controls the anti-entropy interval. This is how often
 	// the agent attempts to reconcile it's local state with the server'
 	// representation of our state. Defaults to every 60s.
@@ -429,6 +433,9 @@ func MergeConfig(a, b *Config) *Config {
 	if b.PidFile != "" {
 		result.PidFile = b.PidFile
 	}
+	if b.EnableSyslog {
+		result.EnableSyslog = true
+	}
 
 	// Copy the start join addresses
 	result.StartJoin = make([]string, 0, len(a.StartJoin)+len(b.StartJoin))

command/agent/config_test.go

@@ -268,6 +268,17 @@ func TestDecodeConfig(t *testing.T) {
 	if config.PidFile != "/tmp/consul/pid" {
 		t.Fatalf("bad: %#v", config)
 	}
+
+	// Syslog
+	input = `{"enable_syslog": true}`
+	config, err = DecodeConfig(bytes.NewReader([]byte(input)))
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if !config.EnableSyslog {
+		t.Fatalf("bad: %#v", config)
+	}
 }
 
 func TestDecodeConfig_Service(t *testing.T) {
@@ -400,6 +411,7 @@ func TestMergeConfig(t *testing.T) {
 		Services:       []*ServiceDefinition{nil},
 		StartJoin:      []string{"1.1.1.1"},
 		UiDir:          "/opt/consul-ui",
+		EnableSyslog:   true,
 	}
 
 	c := MergeConfig(a, b)

website/source/docs/agent/options.html.markdown

@@ -100,6 +100,9 @@ The options below are all specified on the command-line.
   participate in a WAN gossip pool with server nodes in other datacenters. Servers act as gateways
   to other datacenters and forward traffic as appropriate.
 
+* `-syslog` - This flag enables logging to syslog. This is only supported on Linux
+  and OSX. It will result in an error if provided on Windows.
+
 * `-ui-dir` - This flag provides a the directory containing the Web UI resources
   for Consul. This must be provided to enable the Web UI. Directory must be readable.
 
@@ -159,6 +162,8 @@ definitions support being updated during a reload.
 
 * `advertise_addr` - Equivalent to the `-advertise` command-line flag.
 
+* `enable_syslog` - Equivalent to the `-syslog` command-line flag.
+
 * `ca_file` - This provides a the file path to a PEM encoded certificate authority.
   The certificate authority is used to check the authenticity of client and server
   connections with the appropriate `verify_incoming` or `verify_outgoing` flags.