agent: auto-register the consul service on server nodes

command/agent/agent.go

@@ -14,6 +14,9 @@ import (
 	"github.com/hashicorp/serf/serf"
 )
 
+// The internal service ID of the consul service
+const internalServiceID = "consul"
+
 /*
  The agent is the long running process that is run on every machine.
  It exposes an RPC interface that is used by the CLI to control the
@@ -114,6 +117,14 @@ func Create(config *Config, logOutput io.Writer) (*Agent, error) {
 	if config.Server {
 		err = agent.setupServer()
 		agent.state.SetIface(agent.server)
+
+		// Automatically register the "consul" service on server nodes
+		consulService := structs.NodeService{
+			Service: internalServiceID,
+			ID:      internalServiceID,
+			Port:    agent.config.Ports.Server,
+		}
+		agent.state.AddService(&consulService)
 	} else {
 		err = agent.setupClient()
 		agent.state.SetIface(agent.client)
@@ -452,6 +463,12 @@ func (a *Agent) AddService(service *structs.NodeService, chkType *CheckType) err
 // RemoveService is used to remove a service entry.
 // The agent will make a best effort to ensure it is deregistered
 func (a *Agent) RemoveService(serviceID string) error {
+	// Protect "consul" service from deletion by a user
+	if a.server != nil && serviceID == internalServiceID {
+		return fmt.Errorf(
+			"Deregistering the %s service is not allowed", internalServiceID)
+	}
+
 	// Remove service immeidately
 	a.state.RemoveService(serviceID)
 

command/agent/agent_test.go

@@ -146,6 +146,11 @@ func TestAgent_RemoveService(t *testing.T) {
 		t.Fatalf("err: %v", err)
 	}
 
+	// Remove the consul service
+	if err := agent.RemoveService("consul"); err == nil {
+		t.Fatalf("should have errored")
+	}
+
 	srv := &structs.NodeService{
 		ID:      "redis",
 		Service: "redis",
@@ -315,3 +320,14 @@ func TestAgent_UpdateCheck(t *testing.T) {
 		t.Fatalf("bad: %v", status)
 	}
 }
+
+func TestAgent_ConsulService(t *testing.T) {
+	dir, agent := makeAgent(t, nextConfig())
+	defer os.RemoveAll(dir)
+	defer agent.Shutdown()
+
+	services := agent.state.Services()
+	if _, ok := services[internalServiceID]; !ok {
+		t.Fatalf("%s service should be registered", internalServiceID)
+	}
+}

command/agent/user_event.go

@@ -157,11 +157,6 @@ func (a *Agent) shouldProcessUserEvent(msg *UserEvent) bool {
 	}
 
 	if msg.ServiceFilter != "" {
-		// Handle "consul" service on server nodes
-		if a.server != nil && msg.ServiceFilter == "consul" {
-			return true
-		}
-
 		re, err := regexp.Compile(msg.ServiceFilter)
 		if err != nil {
 			a.logger.Printf("[ERR] agent: Failed to parse service filter '%s' for event '%s': %v",