Remove GRPC from element

I came in like a wrecking ball....

I think the grpc server and rpc configuration for the server should be
handled outside of this package.  There are many ways to configure it
and we need more flexability on start and shutdown for grpc services.
Signal handling should be in the caller.

agent.go

@@ -5,7 +5,6 @@ import (
 	"time"
 
 	"github.com/hashicorp/memberlist"
-	"google.golang.org/grpc"
 )
 
 const (
@@ -24,7 +23,6 @@ type Agent struct {
 	members            *memberlist.Memberlist
 	peerUpdateChan     chan bool
 	nodeEventChan      chan *NodeEvent
-	grpcServer         *grpc.Server
 	registeredServices map[string]struct{}
 	memberConfig       *memberlist.Config
 }
@@ -33,7 +31,7 @@ type Agent struct {
 func NewAgent(cfg *Config) (*Agent, error) {
 	updateCh := make(chan bool)
 	nodeEventCh := make(chan *NodeEvent)
-	mc, err := setupMemberlistConfig(cfg, updateCh, nodeEventCh)
+	mc, err := cfg.memberListConfig(updateCh, nodeEventCh)
 	if err != nil {
 		return nil, err
 	}
@@ -42,13 +40,11 @@ func NewAgent(cfg *Config) (*Agent, error) {
 	if err != nil {
 		return nil, err
 	}
-	grpcServer := grpc.NewServer()
 	return &Agent{
 		config:         cfg,
 		members:        ml,
 		peerUpdateChan: updateCh,
 		nodeEventChan:  nodeEventCh,
-		grpcServer:     grpcServer,
 		memberConfig:   mc,
 	}, nil
 }

config.go

@@ -1,9 +1,10 @@
 package element
 
 import (
-	"fmt"
 	"io/ioutil"
 	"log"
+	"net"
+	"strconv"
 
 	"github.com/hashicorp/memberlist"
 )
@@ -24,20 +25,14 @@ const (
 type Config struct {
 	// NodeName is the name of the node.  Each node must have a unique name in the cluster.
 	NodeName string
-	// AgentAddr is the address on which the agent will serve the GRPC services
-	AgentAddr string
-	// AgentPort is the port on which the agent will serve the GRPC services
-	AgentPort int
+	// Address on which the agent will serve the GRPC services
+	Address string
 	// ConnectionType is the connection type the agent will use
 	ConnectionType string
-	// BindAddr is the cluster bind address
-	BindAddr string
-	// BindPort is the cluster bind port
-	BindPort int
-	// AdvertiseAddr is the cluster address that will be used for membership communication
-	AdvertiseAddr string
-	// AdvertisePort is the cluster port that will be used for membership communication
-	AdvertisePort int
+	// ClusterAddress bind address
+	ClusterAddress string
+	// AdvertiseAddress for nat traversal
+	AdvertiseAddress string
 	// Peers is a local cache of peer members
 	Peers []string
 }
@@ -46,7 +41,7 @@ func (a *Agent) Config() *Config {
 	return a.config
 }
 
-func setupMemberlistConfig(cfg *Config, peerUpdateChan chan bool, nodeEventChan chan *NodeEvent) (*memberlist.Config, error) {
+func (cfg *Config) memberListConfig(peerUpdateChan chan bool, nodeEventChan chan *NodeEvent) (*memberlist.Config, error) {
 	var mc *memberlist.Config
 	switch cfg.ConnectionType {
 	case string(Local):
@@ -60,26 +55,32 @@ func setupMemberlistConfig(cfg *Config, peerUpdateChan chan bool, nodeEventChan
 	}
 
 	mc.Name = cfg.NodeName
-	mc.Delegate = NewAgentDelegate(cfg.NodeName, fmt.Sprintf("%s:%d", cfg.AgentAddr, cfg.AgentPort), peerUpdateChan, nodeEventChan)
+	mc.Delegate = NewAgentDelegate(cfg.NodeName, cfg.Address, peerUpdateChan, nodeEventChan)
 	mc.Events = NewEventHandler(nodeEventChan)
 
 	// disable logging for memberlist
 	// TODO: enable if debug
 	mc.Logger = log.New(ioutil.Discard, "", 0)
 
+	host, port, err := net.SplitHostPort(cfg.ClusterAddress)
+	if err != nil {
+		return nil, err
+	}
 	// ml overrides for connection
-	if v := cfg.BindAddr; v != "" {
-		mc.BindAddr = v
+	if v := host; v != "" {
+		mc.BindAddr = host
 	}
-	if v := cfg.BindPort; v > 0 {
-		mc.BindPort = v
+	if v := port; v != "" {
+		mc.BindPort, _ = strconv.Atoi(port)
 	}
-	if v := cfg.AdvertiseAddr; v != "" {
-		mc.AdvertiseAddr = v
+	if host, port, err = net.SplitHostPort(cfg.ClusterAddress); err != nil {
+		return nil, err
 	}
-	if v := cfg.AdvertisePort; v > 0 {
-		mc.AdvertisePort = v
+	if v := host; v != "" {
+		mc.AdvertiseAddr = host
+	}
+	if v := port; v != "" {
+		mc.AdvertisePort, _ = strconv.Atoi(port)
 	}
-
 	return mc, nil
 }

peers.go

@@ -2,7 +2,6 @@ package element
 
 import (
 	"encoding/json"
-	"fmt"
 	"time"
 )
 
@@ -35,7 +34,7 @@ func (a *Agent) Peers() ([]*PeerAgent, error) {
 func (a *Agent) LocalNode() (*PeerAgent, error) {
 	return &PeerAgent{
 		Name:    a.config.NodeName,
-		Addr:    fmt.Sprintf("%s:%d", a.config.AgentAddr, a.config.AgentPort),
+		Addr:    a.config.Address,
 		Updated: time.Now(),
 	}, nil
 }

register.go

@@ -1,13 +0,0 @@
-package element
-
-import "fmt"
-
-// Register registers a GRPC service with the agent
-func (a *Agent) Register(svc Service) error {
-	id := svc.ID()
-	if _, exists := a.registeredServices[id]; exists {
-		return fmt.Errorf("service %s already registered", id)
-	}
-	svc.Register(a.grpcServer)
-	return nil
-}

service.go

@@ -1,10 +0,0 @@
-package element
-
-import "google.golang.org/grpc"
-
-type Service interface {
-	// ID is the name of the service
-	ID() string
-	// Register is used to register the GRPC service
-	Register(srv *grpc.Server) error
-}

shutdown.go

@@ -5,10 +5,5 @@ func (a *Agent) Shutdown() error {
 	if err := a.members.Leave(nodeUpdateTimeout); err != nil {
 		return err
 	}
-
-	if err := a.members.Shutdown(); err != nil {
-		return err
-	}
-
-	return nil
+	return a.members.Shutdown()
 }

start.go

@@ -1,44 +1,18 @@
 package element
 
 import (
-	"fmt"
-	"net"
+	"os"
 
 	"github.com/sirupsen/logrus"
 )
 
-// Start activates the GRPC listener as well as joins the cluster if specified and blocks until a SIGTERM or SIGINT is received
-func (a *Agent) Start() error {
-	logrus.WithFields(logrus.Fields{
-		"grpc":      fmt.Sprintf("%s:%d", a.config.AgentAddr, a.config.AgentPort),
-		"bind":      fmt.Sprintf("%s:%d", a.config.BindAddr, a.config.BindPort),
-		"advertise": fmt.Sprintf("%s:%d", a.config.AdvertiseAddr, a.config.AdvertisePort),
-	}).Info("starting agent")
-	l, err := net.Listen("tcp", fmt.Sprintf("%s:%d", a.config.AgentAddr, a.config.AgentPort))
-	if err != nil {
-		return err
-	}
-	go a.grpcServer.Serve(l)
-
-	// start node metadata updater
+// Start handles cluster events
+func (a *Agent) Start(s chan os.Signal) {
 	go func() {
-		for {
-			<-a.peerUpdateChan
+		for range a.peerUpdateChan {
 			if err := a.members.UpdateNode(nodeUpdateTimeout); err != nil {
 				logrus.Errorf("error updating node metadata: %s", err)
 			}
 		}
 	}()
-
-	if len(a.config.Peers) > 0 {
-		logrus.Debugf("joining peers: %v", a.config.Peers)
-		n, err := a.members.Join(a.config.Peers)
-		if err != nil {
-			return err
-		}
-
-		logrus.Infof("joined %d peer(s)", n)
-	}
-
-	return nil
 }