ui: added node constraint solver to UI

server/admin.go

@@ -25,6 +25,8 @@ import (
 	"strings"
 	"time"
 
+	yaml "gopkg.in/yaml.v2"
+
 	"github.com/gogo/protobuf/proto"
 	gwruntime "github.com/grpc-ecosystem/grpc-gateway/runtime"
 	"github.com/pkg/errors"
@@ -1306,3 +1308,31 @@ func (s *adminServer) queryDescriptorIDPath(
 	}
 	return path, nil
 }
+
+// Constraints runs a set of constraints against the current stores and returns
+// a list of candidates that satisfy them along with their scores.
+func (s *adminServer) Constraints(ctx context.Context, req *serverpb.ConstraintsRequest) (*serverpb.ConstraintsResponse, error) {
+	input := fmt.Sprintf("[%s]", req.Constraints)
+	var constraints config.Constraints
+	if err := yaml.Unmarshal([]byte(input), &constraints); err != nil {
+		return nil, err
+	}
+
+	rs := storage.MakeDefaultRuleSolver(s.server.storePool)
+	candidates, err := rs.Solve(constraints, nil)
+	if err != nil {
+		return nil, err
+	}
+	resp := serverpb.ConstraintsResponse{
+		Stores:     s.server.storePool.GetStoreDescs(),
+		Candidates: make([]serverpb.Candidate, len(candidates)),
+	}
+
+	for i, c := range candidates {
+		resp.Candidates[i] = serverpb.Candidate{
+			Desc:  c.Store,
+			Score: c.Score,
+		}
+	}
+	return &resp, nil
+}

server/admin_test.go

@@ -36,6 +36,7 @@ import (
 
 	"github.com/cockroachdb/cockroach/base"
 	"github.com/cockroachdb/cockroach/config"
+	"github.com/cockroachdb/cockroach/roachpb"
 	"github.com/cockroachdb/cockroach/security"
 	"github.com/cockroachdb/cockroach/server/serverpb"
 	"github.com/cockroachdb/cockroach/sql"
@@ -894,3 +895,41 @@ func TestClusterFreeze(t *testing.T) {
 		}
 	}
 }
+
+func TestConstraints(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+	s, _, _ := serverutils.StartServer(t, base.TestServerArgs{})
+	defer s.Stopper().Stop()
+
+	testCases := []struct {
+		constraints string
+		want        []roachpb.StoreID
+	}{
+		{
+			"",
+			[]roachpb.StoreID{1},
+		},
+		{
+			"+nonexistant",
+			nil,
+		},
+	}
+
+	for i, tc := range testCases {
+		var resp serverpb.ConstraintsResponse
+		path := "constraints/" + tc.constraints
+		if err := getAdminJSONProto(s, path, &resp); err != nil {
+			t.Fatal(err)
+		}
+		if len(resp.Candidates) != len(tc.want) {
+			t.Errorf("%d: GET %q len(%+v) = %d; not %d", i, path, resp.Candidates, len(resp.Candidates), len(tc.want))
+			continue
+		}
+		for j, id := range tc.want {
+			rid := resp.Candidates[j].Desc.StoreID
+			if rid != id {
+				t.Errorf("%d: GET %q [%d] = %+v; not %+v", i, path, j, rid, id)
+			}
+		}
+	}
+}