agent: fix logging

* use agent logger for consul/serf/raft/dns/agent/...
* support optional id for concurrent tests

command/agent/agent.go

@@ -77,6 +77,10 @@ type clientServer interface {
 // mode, it runs a full Consul server. In client-only mode, it only forwards
 // requests to other Consul servers.
 type Agent struct {
+	// id is an optional log prefix.
+	id string
+
+	// config is the agent configuration.
 	config *Config
 
 	// Used for writing our logs
@@ -207,10 +211,13 @@ func NewAgent(c *Config) (*Agent, error) {
 func (a *Agent) Start() error {
 	c := a.config
 
-	if a.LogOutput == nil {
-		a.LogOutput = os.Stderr
+	logOutput := a.LogOutput
+	if a.logger == nil {
+		if logOutput == nil {
+			logOutput = os.Stderr
+		}
+		a.logger = log.New(logOutput, a.id, log.LstdFlags)
 	}
-	a.logger = log.New(a.LogOutput, "", log.LstdFlags)
 
 	// Retrieve or generate the node ID before setting up the rest of the
 	// agent, which depends on it.
@@ -280,7 +287,7 @@ func (a *Agent) Start() error {
 
 	// start dns server
 	if c.Ports.DNS > 0 {
-		srv, err := NewDNSServer(a, &c.DNSConfig, a.LogOutput, c.Domain, a.dnsAddr.String(), c.DNSRecursors)
+		srv, err := NewDNSServer(a, &c.DNSConfig, logOutput, a.logger, c.Domain, a.dnsAddr.String(), c.DNSRecursors)
 		if err != nil {
 			return fmt.Errorf("error starting DNS server: %s", err)
 		}
@@ -765,7 +772,7 @@ func (a *Agent) makeServer() (*consul.Server, error) {
 	if err := a.setupKeyrings(config); err != nil {
 		return nil, fmt.Errorf("Failed to configure keyring: %v", err)
 	}
-	server, err := consul.NewServer(config)
+	server, err := consul.NewServerLogger(config, a.logger)
 	if err != nil {
 		return nil, fmt.Errorf("Failed to start Consul server: %v", err)
 	}
@@ -1615,7 +1622,7 @@ func (a *Agent) RemoveCheck(checkID types.CheckID, persist bool) error {
 			return err
 		}
 	}
-	log.Printf("[DEBUG] agent: removed check %q", checkID)
+	a.logger.Printf("[DEBUG] agent: removed check %q", checkID)
 	return nil
 }
 

command/agent/dns.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"log"
 	"net"
+	"os"
 	"strings"
 	"sync"
 	"time"
@@ -53,7 +54,13 @@ func (d *DNSServer) Shutdown() {
 }
 
 // NewDNSServer starts a new DNS server to provide an agent interface
-func NewDNSServer(agent *Agent, config *DNSConfig, logOutput io.Writer, domain string, bind string, recursors []string) (*DNSServer, error) {
+func NewDNSServer(agent *Agent, config *DNSConfig, logOutput io.Writer, logger *log.Logger, domain string, bind string, recursors []string) (*DNSServer, error) {
+	if logger == nil {
+		if logOutput == nil {
+			logOutput = os.Stderr
+		}
+		logger = log.New(logOutput, "", log.LstdFlags)
+	}
 	// Make sure domain is FQDN, make it case insensitive for ServeMux
 	domain = dns.Fqdn(strings.ToLower(domain))
 
@@ -86,7 +93,7 @@ func NewDNSServer(agent *Agent, config *DNSConfig, logOutput io.Writer, domain s
 		dnsServerTCP: serverTCP,
 		domain:       domain,
 		recursors:    recursors,
-		logger:       log.New(logOutput, "", log.LstdFlags),
+		logger:       logger,
 	}
 
 	// Register mux handler, for reverse lookup

consul/server.go

@@ -210,9 +210,13 @@ type endpoints struct {
 	Txn           *Txn
 }
 
+func NewServer(config *Config) (*Server, error) {
+	return NewServerLogger(config, nil)
+}
+
 // NewServer is used to construct a new Consul server from the
 // configuration, potentially returning an error
-func NewServer(config *Config) (*Server, error) {
+func NewServerLogger(config *Config, l *log.Logger) (*Server, error) {
 	// Check the protocol version.
 	if err := config.CheckProtocolVersion(); err != nil {
 		return nil, err
@@ -232,7 +236,10 @@ func NewServer(config *Config) (*Server, error) {
 	if config.LogOutput == nil {
 		config.LogOutput = os.Stderr
 	}
-	logger := log.New(config.LogOutput, "", log.LstdFlags)
+	logger := l
+	if logger == nil {
+		logger = log.New(config.LogOutput, "", log.LstdFlags)
+	}
 
 	// Check if TLS is enabled
 	if config.CAFile != "" || config.CAPath != "" {
@@ -403,6 +410,7 @@ func (s *Server) setupSerf(conf *serf.Config, ch chan serf.Event, path string, w
 	}
 	conf.MemberlistConfig.LogOutput = s.config.LogOutput
 	conf.LogOutput = s.config.LogOutput
+	conf.Logger = s.logger
 	conf.EventCh = ch
 	if !s.config.DevMode {
 		conf.SnapshotPath = filepath.Join(s.config.DataDir, path)
@@ -454,6 +462,7 @@ func (s *Server) setupRaft() error {
 
 	// Make sure we set the LogOutput.
 	s.config.RaftConfig.LogOutput = s.config.LogOutput
+	s.config.RaftConfig.Logger = s.logger
 
 	// Versions of the Raft protocol below 3 require the LocalID to match the network
 	// address of the transport.