nomad: support listing regions

command/agent/http.go

@@ -109,6 +109,8 @@ func (s *HTTPServer) registerHandlers(enableDebug bool) {
 	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/regions", s.wrap(s.RegionsListRequest))
+
 	s.mux.HandleFunc("/v1/status/leader", s.wrap(s.StatusLeaderRequest))
 	s.mux.HandleFunc("/v1/status/peers", s.wrap(s.StatusPeersRequest))
 

command/agent/regions_endpoint.go

@@ -0,0 +1,24 @@
+package agent
+
+import (
+	"net/http"
+
+	"github.com/hashicorp/nomad/nomad/structs"
+)
+
+func (s *HTTPServer) RegionsListRequest(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
+	if req.Method != "GET" {
+		return nil, CodedError(405, ErrInvalidMethod)
+	}
+
+	var args structs.GenericRequest
+	if s.parse(resp, req, &args.Region, &args.QueryOptions) {
+		return nil, nil
+	}
+
+	var regions []string
+	if err := s.agent.RPC("Region.List", &args, &regions); err != nil {
+		return nil, err
+	}
+	return regions, nil
+}

nomad/regions_endpoint.go

@@ -0,0 +1,18 @@
+package nomad
+
+import "github.com/hashicorp/nomad/nomad/structs"
+
+// Region is used to query and list the known regions
+type Region struct {
+	srv *Server
+}
+
+// List is used to list all of the known regions.
+func (r *Region) List(args *structs.GenericRequest, reply *[]string) error {
+	if done, err := r.srv.forward("Region.List", args, args, reply); done {
+		return err
+	}
+
+	*reply = r.srv.Regions()
+	return nil
+}

nomad/server.go

@@ -134,6 +134,7 @@ type endpoints struct {
 	Eval   *Eval
 	Plan   *Plan
 	Alloc  *Alloc
+	Region *Region
 }
 
 // NewServer is used to construct a new Nomad server from the
@@ -353,6 +354,7 @@ func (s *Server) setupRPC(tlsWrap tlsutil.DCWrapper) error {
 	s.endpoints.Eval = &Eval{s}
 	s.endpoints.Plan = &Plan{s}
 	s.endpoints.Alloc = &Alloc{s}
+	s.endpoints.Region = &Region{s}
 
 	// Register the handlers
 	s.rpcServer.Register(s.endpoints.Status)
@@ -361,6 +363,7 @@ func (s *Server) setupRPC(tlsWrap tlsutil.DCWrapper) error {
 	s.rpcServer.Register(s.endpoints.Eval)
 	s.rpcServer.Register(s.endpoints.Plan)
 	s.rpcServer.Register(s.endpoints.Alloc)
+	s.rpcServer.Register(s.endpoints.Region)
 
 	list, err := net.ListenTCP("tcp", s.config.RPCAddr)
 	if err != nil {
@@ -612,6 +615,18 @@ func (s *Server) State() *state.StateStore {
 	return s.fsm.State()
 }
 
+// Regions returns the known regions in the cluster.
+func (s *Server) Regions() []string {
+	s.peerLock.Lock()
+	defer s.peerLock.Unlock()
+
+	regions := make([]string, 0, len(s.peers))
+	for region, _ := range s.peers {
+		regions = append(regions, region)
+	}
+	return regions
+}
+
 // inmemCodec is used to do an RPC call without going over a network
 type inmemCodec struct {
 	method string