agent: refactor keyring loader

command/agent/agent.go

@@ -115,7 +115,7 @@ func Create(config *Config, logOutput io.Writer) (*Agent, error) {
 	agent.state.Init(config, agent.logger)
 
 	// Setup encryption keyring files
-	if !config.DisableKeyring && config.EncryptKey != "" {
+	if config.PersistKeyring && config.EncryptKey != "" {
 		serfDir := filepath.Join(config.DataDir, "serf")
 		if err := os.MkdirAll(serfDir, 0700); err != nil {
 			return nil, err
@@ -200,20 +200,17 @@ func (a *Agent) consulConfig() *consul.Config {
 	if a.config.DataDir != "" {
 		base.DataDir = a.config.DataDir
 	}
-	if a.config.EncryptKey != "" && a.config.DisableKeyring {
+	if a.config.EncryptKey != "" && !a.config.PersistKeyring {
 		key, _ := a.config.EncryptBytes()
 		base.SerfLANConfig.MemberlistConfig.SecretKey = key
 		base.SerfWANConfig.MemberlistConfig.SecretKey = key
 	}
-	if !a.config.DisableKeyring {
+	if a.config.PersistKeyring {
 		lanKeyring := filepath.Join(base.DataDir, "serf", "keyring_lan")
 		wanKeyring := filepath.Join(base.DataDir, "serf", "keyring_wan")
 
 		base.SerfLANConfig.KeyringFile = lanKeyring
 		base.SerfWANConfig.KeyringFile = wanKeyring
-
-		base.SerfLANConfig.MemberlistConfig.Keyring = loadKeyringFile(lanKeyring)
-		base.SerfWANConfig.MemberlistConfig.Keyring = loadKeyringFile(wanKeyring)
 	}
 	if a.config.NodeName != "" {
 		base.NodeName = a.config.NodeName
@@ -303,9 +300,6 @@ func (a *Agent) consulConfig() *consul.Config {
 		}
 	}
 
-	// Setup gossip keyring configuration
-	base.DisableKeyring = a.config.DisableKeyring
-
 	// Setup the loggers
 	base.LogOutput = a.logOutput
 	return base
@@ -313,6 +307,16 @@ func (a *Agent) consulConfig() *consul.Config {
 
 // setupServer is used to initialize the Consul server
 func (a *Agent) setupServer() error {
+	config := a.consulConfig()
+
+	// Load a keyring file, if present
+	if err := loadKeyringFile(config.SerfLANConfig); err != nil {
+		return err
+	}
+	if err := loadKeyringFile(config.SerfWANConfig); err != nil {
+		return err
+	}
+
 	server, err := consul.NewServer(a.consulConfig())
 	if err != nil {
 		return fmt.Errorf("Failed to start Consul server: %v", err)
@@ -703,21 +707,25 @@ func (a *Agent) deletePid() error {
 }
 
 // loadKeyringFile will load a keyring out of a file
-func loadKeyringFile(keyringFile string) *memberlist.Keyring {
-	if _, err := os.Stat(keyringFile); err != nil {
+func loadKeyringFile(c *serf.Config) error {
+	if c.KeyringFile == "" {
 		return nil
 	}
 
+	if _, err := os.Stat(c.KeyringFile); err != nil {
+		return err
+	}
+
 	// Read in the keyring file data
-	keyringData, err := ioutil.ReadFile(keyringFile)
+	keyringData, err := ioutil.ReadFile(c.KeyringFile)
 	if err != nil {
-		return nil
+		return err
 	}
 
 	// Decode keyring JSON
 	keys := make([]string, 0)
 	if err := json.Unmarshal(keyringData, &keys); err != nil {
-		return nil
+		return err
 	}
 
 	// Decode base64 values
@@ -725,7 +733,7 @@ func loadKeyringFile(keyringFile string) *memberlist.Keyring {
 	for i, key := range keys {
 		keyBytes, err := base64.StdEncoding.DecodeString(key)
 		if err != nil {
-			return nil
+			return err
 		}
 		keysDecoded[i] = keyBytes
 	}
@@ -733,11 +741,13 @@ func loadKeyringFile(keyringFile string) *memberlist.Keyring {
 	// Create the keyring
 	keyring, err := memberlist.NewKeyring(keysDecoded, keysDecoded[0])
 	if err != nil {
-		return nil
+		return err
 	}
 
+	c.MemberlistConfig.Keyring = keyring
+
 	// Success!
-	return keyring
+	return nil
 }
 
 // ListKeysLAN returns the keys installed on the LAN gossip pool

command/agent/command.go

@@ -67,7 +67,7 @@ func (c *Command) readConfig() *Config {
 	cmdFlags.StringVar(&cmdConfig.UiDir, "ui-dir", "", "path to the web UI directory")
 	cmdFlags.StringVar(&cmdConfig.PidFile, "pid-file", "", "path to file to store PID")
 	cmdFlags.StringVar(&cmdConfig.EncryptKey, "encrypt", "", "gossip encryption key")
-	cmdFlags.BoolVar(&cmdConfig.DisableKeyring, "disable-keyring", false, "disable use of encryption keyring")
+	cmdFlags.BoolVar(&cmdConfig.PersistKeyring, "persist-keyring", false, "persist keyring changes")
 
 	cmdFlags.BoolVar(&cmdConfig.Server, "server", false, "run agent as server")
 	cmdFlags.BoolVar(&cmdConfig.Bootstrap, "bootstrap", false, "enable server bootstrap mode")
@@ -802,10 +802,6 @@ Options:
   -data-dir=path           Path to a data directory to store agent state
   -dc=east-aws             Datacenter of the agent
   -encrypt=key             Provides the gossip encryption key
-  -disable-keyring         Disables the use of an encryption keyring. The
-                           Default behavior is to persist encryption keys using
-                           a keyring file, and reload the keys on subsequent
-                           starts. This argument disables keyring persistence.
   -join=1.2.3.4            Address of an agent to join at start time.
                            Can be specified multiple times.
   -join-wan=1.2.3.4        Address of an agent to join -wan at start time.
@@ -823,6 +819,7 @@ Options:
   -log-level=info          Log level of the agent.
   -node=hostname           Name of this node. Must be unique in the cluster
   -protocol=N              Sets the protocol version. Defaults to latest.
+  -persist-keyring         Enable encryption keyring persistence.
   -rejoin                  Ignores a previous leave and attempts to rejoin the cluster.
   -server                  Switches agent to server mode.
   -syslog                  Enables logging to syslog

command/agent/config.go

@@ -104,13 +104,13 @@ type Config struct {
 	// recursors array.
 	DNSRecursor string `mapstructure:"recursor"`
 
-	// Disable use of an encryption keyring.
-	DisableKeyring bool `mapstructure:"disable_keyring"`
-
 	// DNSRecursors can be set to allow the DNS servers to recursively
 	// resolve non-consul domains
 	DNSRecursors []string `mapstructure:"recursors"`
 
+	// Disable use of an encryption keyring.
+	DisableKeyring bool `mapstructure:"disable_keyring"`
+
 	// DNS configuration
 	DNSConfig DNSConfig `mapstructure:"dns_config"`
 
@@ -150,6 +150,11 @@ type Config struct {
 	// the TERM signal. Defaults false. This can be changed on reload.
 	LeaveOnTerm bool `mapstructure:"leave_on_terminate"`
 
+	// Enable keyring persistence. There are currently two keyrings; one for
+	// the LAN serf cluster and the other for the WAN. Each will maintain its
+	// own keyring file in the agent's data directory.
+	PersistKeyring bool `mapstructure:"persist_keyring"`
+
 	// SkipLeaveOnInt controls if Serf skips a graceful leave when receiving
 	// the INT signal. Defaults false. This can be changed on reload.
 	SkipLeaveOnInt bool `mapstructure:"skip_leave_on_interrupt"`
@@ -691,8 +696,8 @@ func MergeConfig(a, b *Config) *Config {
 	if b.EncryptKey != "" {
 		result.EncryptKey = b.EncryptKey
 	}
-	if b.DisableKeyring {
-		result.DisableKeyring = true
+	if b.PersistKeyring {
+		result.PersistKeyring = true
 	}
 	if b.LogLevel != "" {
 		result.LogLevel = b.LogLevel

consul/config.go

@@ -165,11 +165,6 @@ type Config struct {
 	// UserEventHandler callback can be used to handle incoming
 	// user events. This function should not block.
 	UserEventHandler func(serf.UserEvent)
-
-	// DisableKeyring is used to disable persisting the encryption keyring to
-	// filesystem. By default, if encryption is enabled, Consul will create a
-	// file inside of the DataDir to keep track of changes made to the ring.
-	DisableKeyring bool
 }
 
 // CheckVersion is used to check if the ProtocolVersion is valid