Add go-discover support to Nomad clients

client/client.go

@@ -283,7 +283,7 @@ func NewClient(cfg *config.Config, consulCatalog consul.CatalogAPI, consulServic
 	// Set the preconfigured list of static servers
 	c.configLock.RLock()
 	if len(c.configCopy.Servers) > 0 {
-		if err := c.setServersImpl(c.configCopy.Servers, true); err != nil {
+		if _, err := c.setServersImpl(c.configCopy.Servers, true); err != nil {
 			logger.Printf("[WARN] client: None of the configured servers are valid: %v", err)
 		}
 	}
@@ -623,7 +623,7 @@ func (c *Client) GetServers() []string {
 
 // SetServers sets a new list of nomad servers to connect to. As long as one
 // server is resolvable no error is returned.
-func (c *Client) SetServers(in []string) error {
+func (c *Client) SetServers(in []string) (int, error) {
 	return c.setServersImpl(in, false)
 }
 
@@ -633,7 +633,7 @@ func (c *Client) SetServers(in []string) error {
 //
 // Force should be used when setting the servers from the initial configuration
 // since the server may be starting up in parallel and initial pings may fail.
-func (c *Client) setServersImpl(in []string, force bool) error {
+func (c *Client) setServersImpl(in []string, force bool) (int, error) {
 	var mu sync.Mutex
 	var wg sync.WaitGroup
 	var merr multierror.Error
@@ -673,13 +673,13 @@ func (c *Client) setServersImpl(in []string, force bool) error {
 	// Only return errors if no servers are valid
 	if len(endpoints) == 0 {
 		if len(merr.Errors) > 0 {
-			return merr.ErrorOrNil()
+			return 0, merr.ErrorOrNil()
 		}
-		return noServersErr
+		return 0, noServersErr
 	}
 
 	c.servers.SetServers(endpoints)
-	return nil
+	return len(endpoints), nil
 }
 
 // restoreState is used to restore our state from the data dir

client/client_test.go

@@ -975,13 +975,13 @@ func TestClient_ServerList(t *testing.T) {
 	if s := client.GetServers(); len(s) != 0 {
 		t.Fatalf("expected server lit to be empty but found: %+q", s)
 	}
-	if err := client.SetServers(nil); err != noServersErr {
+	if _, err := client.SetServers(nil); err != noServersErr {
 		t.Fatalf("expected setting an empty list to return a 'no servers' error but received %v", err)
 	}
-	if err := client.SetServers([]string{"123.456.13123.123.13:80"}); err == nil {
+	if _, err := client.SetServers([]string{"123.456.13123.123.13:80"}); err == nil {
 		t.Fatalf("expected setting a bad server to return an error")
 	}
-	if err := client.SetServers([]string{"123.456.13123.123.13:80", "127.0.0.1:1234", "127.0.0.1"}); err == nil {
+	if _, err := client.SetServers([]string{"123.456.13123.123.13:80", "127.0.0.1:1234", "127.0.0.1"}); err == nil {
 		t.Fatalf("expected setting at least one good server to succeed but received: %v", err)
 	}
 	s := client.GetServers()

command/agent/agent_endpoint.go

@@ -222,7 +222,7 @@ func (s *HTTPServer) updateServers(resp http.ResponseWriter, req *http.Request)
 
 	// Set the servers list into the client
 	s.agent.logger.Printf("[TRACE] Adding servers %+q to the client's primary server list", servers)
-	if err := client.SetServers(servers); err != nil {
+	if _, err := client.SetServers(servers); err != nil {
 		s.agent.logger.Printf("[ERR] Attempt to add servers %q to client failed: %v", servers, err)
 		//TODO is this the right error to return?
 		return nil, CodedError(400, err.Error())

command/agent/command.go

@@ -63,9 +63,11 @@ func (c *Command) readConfig() *Config {
 		Client: &ClientConfig{},
 		Consul: &config.ConsulConfig{},
 		Ports:  &Ports{},
-		Server: &ServerConfig{},
-		Vault:  &config.VaultConfig{},
-		ACL:    &ACLConfig{},
+		Server: &ServerConfig{
+			ServerJoin: &ServerJoin{},
+		},
+		Vault: &config.VaultConfig{},
+		ACL:   &ACLConfig{},
 	}
 
 	flags := flag.NewFlagSet("agent", flag.ContinueOnError)
@@ -78,13 +80,16 @@ func (c *Command) readConfig() *Config {
 
 	// Server-only options
 	flags.IntVar(&cmdConfig.Server.BootstrapExpect, "bootstrap-expect", 0, "")
-	flags.BoolVar(&cmdConfig.Server.RejoinAfterLeave, "rejoin", false, "")
-	flags.Var((*flaghelper.StringFlag)(&cmdConfig.Server.StartJoin), "join", "")
-	flags.Var((*flaghelper.StringFlag)(&cmdConfig.Server.RetryJoin), "retry-join", "")
-	flags.IntVar(&cmdConfig.Server.RetryMaxAttempts, "retry-max", 0, "")
-	flags.StringVar(&cmdConfig.Server.RetryInterval, "retry-interval", "", "")
 	flags.StringVar(&cmdConfig.Server.EncryptKey, "encrypt", "", "gossip encryption key")
 	flags.IntVar(&cmdConfig.Server.RaftProtocol, "raft-protocol", 0, "")
+	flags.BoolVar(&cmdConfig.Server.RejoinAfterLeave, "rejoin", false, "")
+	flags.Var((*flaghelper.StringFlag)(&cmdConfig.Server.ServerJoin.StartJoin), "join", "")
+	flags.Var((*flaghelper.StringFlag)(&cmdConfig.Server.ServerJoin.RetryJoin), "retry-join", "")
+	flags.IntVar(&cmdConfig.Server.ServerJoin.RetryMaxAttempts, "retry-max", 0, "")
+	flags.Var((flaghelper.FuncDurationVar)(func(d time.Duration) error {
+		cmdConfig.Server.ServerJoin.RetryInterval = d
+		return nil
+	}), "retry-interval", "")
 
 	// Client-only options
 	flags.StringVar(&cmdConfig.Client.StateDir, "state-dir", "", "")
@@ -267,14 +272,6 @@ func (c *Command) readConfig() *Config {
 		}
 	}
 
-	// Parse the RetryInterval.
-	dur, err := time.ParseDuration(config.Server.RetryInterval)
-	if err != nil {
-		c.Ui.Error(fmt.Sprintf("Error parsing retry interval: %s", err))
-		return nil
-	}
-	config.Server.retryInterval = dur
-
 	// Check that the server is running in at least one mode.
 	if !(config.Server.Enabled || config.Client.Enabled) {
 		c.Ui.Error("Must specify either server, client or dev mode for the agent.")
@@ -547,20 +544,89 @@ func (c *Command) Run(args []string) int {
 	logGate.Flush()
 
 	// Start retry join process
-	c.retryJoinErrCh = make(chan struct{})
-
-	joiner := retryJoiner{
-		join:     c.agent.server.Join,
-		discover: &discover.Discover{},
-		errCh:    c.retryJoinErrCh,
-		logger:   c.agent.logger,
+	if err := c.handleRetryJoin(config); err != nil {
+		c.Ui.Error(err.Error())
+		return 1
 	}
-	go joiner.RetryJoin(config)
 
 	// Wait for exit
 	return c.handleSignals()
 }
 
+// handleRetryJoin is used to start retry joining if it is configured.
+func (c *Command) handleRetryJoin(config *Config) error {
+	c.retryJoinErrCh = make(chan struct{})
+
+	if config.Server.Enabled && len(config.Server.RetryJoin) != 0 {
+		joiner := retryJoiner{
+			discover:      &discover.Discover{},
+			errCh:         c.retryJoinErrCh,
+			logger:        c.agent.logger,
+			serverJoin:    c.agent.server.Join,
+			serverEnabled: true,
+		}
+
+		if err := joiner.Validate(config); err != nil {
+			return err
+		}
+
+		// Remove the duplicate fields
+		if len(config.Server.RetryJoin) != 0 {
+			config.Server.ServerJoin.RetryJoin = config.Server.RetryJoin
+			config.Server.RetryJoin = nil
+		}
+		if config.Server.RetryMaxAttempts != 0 {
+			config.Server.ServerJoin.RetryMaxAttempts = config.Server.RetryMaxAttempts
+			config.Server.RetryMaxAttempts = 0
+		}
+		if config.Server.RetryInterval != 0 {
+			config.Server.ServerJoin.RetryInterval = config.Server.RetryInterval
+			config.Server.RetryInterval = 0
+		}
+
+		c.agent.logger.Printf("[WARN] agent: Using deprecated retry_join fields. Upgrade configuration to use server_join")
+	}
+
+	if config.Server.Enabled &&
+		config.Server.ServerJoin != nil &&
+		len(config.Server.ServerJoin.RetryJoin) != 0 {
+
+		joiner := retryJoiner{
+			discover:      &discover.Discover{},
+			errCh:         c.retryJoinErrCh,
+			logger:        c.agent.logger,
+			serverJoin:    c.agent.server.Join,
+			serverEnabled: true,
+		}
+
+		if err := joiner.Validate(config); err != nil {
+			return err
+		}
+
+		go joiner.RetryJoin(config.Server.ServerJoin)
+	}
+
+	if config.Client.Enabled &&
+		config.Client.ServerJoin != nil &&
+		len(config.Client.ServerJoin.RetryJoin) != 0 {
+		joiner := retryJoiner{
+			discover:      &discover.Discover{},
+			errCh:         c.retryJoinErrCh,
+			logger:        c.agent.logger,
+			clientJoin:    c.agent.client.SetServers,
+			clientEnabled: true,
+		}
+
+		if err := joiner.Validate(config); err != nil {
+			return err
+		}
+
+		go joiner.RetryJoin(config.Client.ServerJoin)
+	}
+
+	return nil
+}
+
 // handleSignals blocks until we get an exit-causing signal
 func (c *Command) handleSignals() int {
 	signalCh := make(chan os.Signal, 4)
@@ -831,12 +897,34 @@ func (c *Command) setupTelemetry(config *Config) (*metrics.InmemSink, error) {
 }
 
 func (c *Command) startupJoin(config *Config) error {
-	if len(config.Server.StartJoin) == 0 || !config.Server.Enabled {
+	// Nothing to do
+	if !config.Server.Enabled {
 		return nil
 	}
 
+	// Validate both old and new aren't being set
+	old := len(config.Server.StartJoin)
+	var new int
+	if config.Server.ServerJoin != nil {
+		new = len(config.Server.ServerJoin.StartJoin)
+	}
+	if old != 0 && new != 0 {
+		return fmt.Errorf("server_join and start_join cannot both be defined; prefer setting the server_join stanza")
+	}
+
+	// Nothing to do
+	if old+new == 0 {
+		return nil
+	}
+
+	// Combine the lists and join
+	joining := config.Server.StartJoin
+	if new != 0 {
+		joining = append(joining, config.Server.ServerJoin.StartJoin...)
+	}
+
 	c.Ui.Output("Joining cluster...")
-	n, err := c.agent.server.Join(config.Server.StartJoin)
+	n, err := c.agent.server.Join(joining)
 	if err != nil {
 		return err
 	}