agent: add HTTP endpoint for querying/modifying the server list

command/agent/agent_endpoint.go

@@ -119,6 +119,44 @@ func (s *HTTPServer) AgentForceLeaveRequest(resp http.ResponseWriter, req *http.
 	return nil, err
 }
 
+func (s *HTTPServer) AgentServersRequest(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
+	switch req.Method {
+	case "PUT", "POST":
+		return s.updateServers(resp, req)
+	case "GET":
+		return s.listServers(resp, req)
+	default:
+		return nil, CodedError(405, ErrInvalidMethod)
+	}
+}
+
+func (s *HTTPServer) listServers(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
+	client := s.agent.Client()
+	if client == nil {
+		return nil, CodedError(501, ErrInvalidMethod)
+	}
+
+	// Get the current list of servers
+	return client.Servers(), nil
+}
+
+func (s *HTTPServer) updateServers(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
+	client := s.agent.Client()
+	if client == nil {
+		return nil, CodedError(501, ErrInvalidMethod)
+	}
+
+	// Get the servers from the request
+	servers := req.URL.Query()["address"]
+	if len(servers) == 0 {
+		return nil, CodedError(400, "missing server address")
+	}
+
+	// Set the servers list into the client
+	client.SetServers(servers)
+	return nil, nil
+}
+
 type agentSelf struct {
 	Config *Config                      `json:"config"`
 	Member Member                       `json:"member,omitempty"`

command/agent/agent_endpoint_test.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 )
 
@@ -103,3 +104,53 @@ func TestHTTP_AgentForceLeave(t *testing.T) {
 		}
 	})
 }
+
+func TestHTTP_AgentSetServers(t *testing.T) {
+	httpTest(t, nil, func(s *TestServer) {
+		// Create the request
+		req, err := http.NewRequest("PUT", "/v1/agent/servers", nil)
+		if err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		// Send the request
+		respW := httptest.NewRecorder()
+		_, err = s.Server.AgentServersRequest(respW, req)
+		if err == nil || !strings.Contains(err.Error(), "missing server address") {
+			t.Fatalf("expected missing servers error, got: %#v", err)
+		}
+
+		// Create a valid request
+		req, err = http.NewRequest("PUT", "/v1/agent/servers?address=foo&address=bar", nil)
+		if err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		// Send the request
+		respW = httptest.NewRecorder()
+		_, err = s.Server.AgentServersRequest(respW, req)
+		if err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		// Retrieve the servers again
+		req, err = http.NewRequest("GET", "/v1/agent/servers", nil)
+		if err != nil {
+			t.Fatalf("err: %s", err)
+		}
+		respW = httptest.NewRecorder()
+
+		// Make the request and check the result
+		out, err := s.Server.AgentServersRequest(respW, req)
+		if err != nil {
+			t.Fatalf("err: %s", err)
+		}
+		servers := out.([]string)
+		if n := len(servers); n != 2 {
+			t.Fatalf("expected 2 servers, got: %d", n)
+		}
+		if servers[0] != "foo" || servers[1] != "bar" {
+			t.Fatalf("bad servers result: %v", servers)
+		}
+	})
+}

command/agent/http.go

@@ -107,6 +107,7 @@ func (s *HTTPServer) registerHandlers(enableDebug bool) {
 	s.mux.HandleFunc("/v1/agent/join", s.wrap(s.AgentJoinRequest))
 	s.mux.HandleFunc("/v1/agent/members", s.wrap(s.AgentMembersRequest))
 	s.mux.HandleFunc("/v1/agent/force-leave", s.wrap(s.AgentForceLeaveRequest))
+	s.mux.HandleFunc("/v1/agent/servers", s.wrap(s.AgentServersRequest))
 
 	s.mux.HandleFunc("/v1/status/leader", s.wrap(s.StatusLeaderRequest))
 	s.mux.HandleFunc("/v1/status/peers", s.wrap(s.StatusPeersRequest))