nomad: include datacenter names in regions reply

command/agent/regions_endpoint.go → command/agent/region_endpoint.go

@@ -16,7 +16,7 @@ func (s *HTTPServer) RegionListRequest(resp http.ResponseWriter, req *http.Reque
 		return nil, nil
 	}
 
-	var regions []string
+	regions := make(map[string][]string)
 	if err := s.agent.RPC("Region.List", &args, &regions); err != nil {
 		return nil, err
 	}

command/agent/region_endpoint_test.go

@@ -3,6 +3,7 @@ package agent
 import (
 	"net/http"
 	"net/http/httptest"
+	"reflect"
 	"testing"
 )
 
@@ -21,9 +22,13 @@ func TestHTTP_RegionList(t *testing.T) {
 			t.Fatalf("err: %v", err)
 		}
 
-		out := obj.([]string)
-		if len(out) != 1 || out[0] != "global" {
-			t.Fatalf("unexpected regions: %#v", out)
+		expect := map[string][]string{
+			"global": []string{"dc1"},
+		}
+
+		out := obj.(map[string][]string)
+		if !reflect.DeepEqual(out, expect) {
+			t.Fatalf("expect: %v, got: %v", expect, out)
 		}
 	})
 }

nomad/regions_endpoint.go

@@ -7,10 +7,10 @@ type Region struct {
 	srv *Server
 }
 
-// List is used to list all of the known regions. No leader forwarding is
-// required for this endpoint because memberlist is used to populate the
-// peers list we read from.
-func (r *Region) List(args *structs.GenericRequest, reply *[]string) error {
+// List is used to list all of the known regions and datacenters. No leader
+// forwarding is required for this endpoint because memberlist is used to
+// populate the peers list we read from.
+func (r *Region) List(args *structs.GenericRequest, reply *map[string][]string) error {
 	*reply = r.srv.Regions()
 	return nil
 }

nomad/regions_endpoint_test.go

@@ -2,6 +2,7 @@ package nomad
 
 import (
 	"fmt"
+	"reflect"
 	"testing"
 
 	"github.com/hashicorp/net-rpc-msgpackrpc"
@@ -29,15 +30,20 @@ func TestRegionList(t *testing.T) {
 		t.Fatalf("Failed joining: %v (%d joined)", err, n)
 	}
 
+	expect := map[string][]string{
+		"region1": []string{"dc1"},
+		"region2": []string{"dc1"},
+	}
+
 	// Query the regions list
 	testutil.WaitForResult(func() (bool, error) {
 		var arg structs.GenericRequest
-		var out []string
+		var out map[string][]string
 		if err := msgpackrpc.CallWithCodec(codec, "Region.List", &arg, &out); err != nil {
 			t.Fatalf("err: %v", err)
 		}
-		if len(out) != 2 || out[0] != "region1" || out[1] != "region2" {
-			t.Fatalf("unexpected regions: %v", out)
+		if !reflect.DeepEqual(out, expect) {
+			t.Fatalf("expect: %v, got: %v", expect, out)
 		}
 		return true, nil
 	}, func(err error) {

nomad/server.go

@@ -615,14 +615,26 @@ func (s *Server) State() *state.StateStore {
 	return s.fsm.State()
 }
 
-// Regions returns the known regions in the cluster.
-func (s *Server) Regions() []string {
+// Regions returns the known regions in the cluster along with a list
+// of the datacenters within each region.
+func (s *Server) Regions() map[string][]string {
 	s.peerLock.RLock()
 	defer s.peerLock.RUnlock()
 
-	regions := make([]string, 0, len(s.peers))
-	for region, _ := range s.peers {
-		regions = append(regions, region)
+	regions := make(map[string][]string, len(s.peers))
+	for region, servers := range s.peers {
+		// Collect all the DC's
+		var dcs []string
+		seen := make(map[string]struct{})
+		for _, srv := range servers {
+			if _, ok := seen[srv.Datacenter]; !ok {
+				dcs = append(dcs, srv.Datacenter)
+			}
+			seen[srv.Datacenter] = struct{}{}
+		}
+
+		// Add the region
+		regions[region] = dcs
 	}
 	return regions
 }

nomad/server_test.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net"
+	"reflect"
 	"sync/atomic"
 	"testing"
 	"time"
@@ -108,11 +109,16 @@ func TestServer_Regions(t *testing.T) {
 		t.Fatalf("Failed joining: %v (%d joined)", err, n)
 	}
 
+	expect := map[string][]string{
+		"region1": []string{"dc1"},
+		"region2": []string{"dc1"},
+	}
+
 	// Try listing the regions
 	testutil.WaitForResult(func() (bool, error) {
 		out := s1.Regions()
-		if len(out) != 2 || out[0] != "region1" || out[1] != "region2" {
-			return false, fmt.Errorf("unexpected regions: %v", out)
+		if !reflect.DeepEqual(out, expect) {
+			return false, fmt.Errorf("expect: %v, got: %v", expect, out)
 		}
 		return true, nil
 	}, func(err error) {

website/source/docs/http/regions.html.md

@@ -3,7 +3,8 @@ layout: "http"
 page_title: "HTTP API: /v1/regions"
 sidebar_current: "docs-http-regions"
 description: >
-  The '/v1/regions' endpoint lists the known cluster regions.
+  The '/v1/regions' endpoint lists the known cluster regions and their
+  datacenters.
 ---
 
 # /v1/regions
@@ -13,7 +14,7 @@ description: >
 <dl>
   <dt>Description</dt>
   <dd>
-    Returns the known region names.
+    Returns a summary of the known regions, including the datacenter names.
   </dd>
 
   <dt>Method</dt>
@@ -31,7 +32,13 @@ description: >
   <dd>
 
     ```javascript
-    ["region1","region2"]
+    {
+        "global": [
+            "dc1",
+            "dc2"
+        ],
+        ...
+    }
     ```
 
   </dd>