Sort nodes before creating consul catalog config

The watch of consul can return for various reasons and not of all of
them require a reload of the config. The order of nodes provided by
consul is not stable so to ensure a identical config is generated for an
identical server set the nodes needs to be sorted before creating the
config.

provider/consul_catalog.go

@@ -2,6 +2,7 @@ package provider
 
 import (
 	"errors"
+	"sort"
 	"strconv"
 	"strings"
 	"text/template"
@@ -41,6 +42,35 @@ type catalogUpdate struct {
 	Nodes   []*api.ServiceEntry
 }
 
+type nodeSorter []*api.ServiceEntry
+
+func (a nodeSorter) Len() int {
+	return len(a)
+}
+
+func (a nodeSorter) Swap(i int, j int) {
+	a[i], a[j] = a[j], a[i]
+}
+
+func (a nodeSorter) Less(i int, j int) bool {
+	lentr := a[i]
+	rentr := a[j]
+
+	ls := strings.ToLower(lentr.Service.Service)
+	lr := strings.ToLower(rentr.Service.Service)
+
+	if ls != lr {
+		return ls < lr
+	}
+	if lentr.Service.Address != rentr.Service.Address {
+		return lentr.Service.Address < rentr.Service.Address
+	}
+	if lentr.Node.Address != rentr.Node.Address {
+		return lentr.Node.Address < rentr.Node.Address
+	}
+	return lentr.Service.Port < rentr.Service.Port
+}
+
 func (provider *ConsulCatalog) watchServices(stopCh <-chan struct{}) <-chan map[string][]string {
 	watchCh := make(chan map[string][]string)
 
@@ -139,7 +169,7 @@ func (provider *ConsulCatalog) getBackendAddress(node *api.ServiceEntry) string
 }
 
 func (provider *ConsulCatalog) getBackendName(node *api.ServiceEntry, index int) string {
-	serviceName := node.Service.Service + "--" + node.Service.Address + "--" + strconv.Itoa(node.Service.Port)
+	serviceName := strings.ToLower(node.Service.Service) + "--" + node.Service.Address + "--" + strconv.Itoa(node.Service.Port)
 
 	for _, tag := range node.Service.Tags {
 		serviceName += "--" + normalize(tag)
@@ -200,6 +230,8 @@ func (provider *ConsulCatalog) buildConfig(catalog []catalogUpdate) *types.Confi
 
 		}
 	}
+	// Ensure a stable ordering of nodes so that identical configurations may be detected
+	sort.Sort(nodeSorter(allNodes))
 
 	templateObjects := struct {
 		Services []*serviceUpdate

provider/consul_catalog_test.go

@@ -2,6 +2,7 @@ package provider
 
 import (
 	"reflect"
+	"sort"
 	"testing"
 
 	"github.com/containous/traefik/types"
@@ -274,3 +275,195 @@ func TestConsulCatalogBuildConfig(t *testing.T) {
 		}
 	}
 }
+
+func TestConsulCatalogNodeSorter(t *testing.T) {
+	cases := []struct {
+		nodes    []*api.ServiceEntry
+		expected []*api.ServiceEntry
+	}{
+		{
+			nodes:    []*api.ServiceEntry{},
+			expected: []*api.ServiceEntry{},
+		},
+		{
+			nodes: []*api.ServiceEntry{
+				{
+					Service: &api.AgentService{
+						Service: "foo",
+						Address: "127.0.0.1",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.1",
+					},
+				},
+			},
+			expected: []*api.ServiceEntry{
+				{
+					Service: &api.AgentService{
+						Service: "foo",
+						Address: "127.0.0.1",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.1",
+					},
+				},
+			},
+		},
+		{
+			nodes: []*api.ServiceEntry{
+				{
+					Service: &api.AgentService{
+						Service: "foo",
+						Address: "127.0.0.2",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.2",
+					},
+				},
+				{
+					Service: &api.AgentService{
+						Service: "bar",
+						Address: "127.0.0.2",
+						Port:    81,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.2",
+					},
+				},
+				{
+					Service: &api.AgentService{
+						Service: "foo",
+						Address: "127.0.0.1",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.1",
+					},
+				},
+				{
+					Service: &api.AgentService{
+						Service: "bar",
+						Address: "127.0.0.2",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.2",
+					},
+				},
+			},
+			expected: []*api.ServiceEntry{
+				{
+					Service: &api.AgentService{
+						Service: "bar",
+						Address: "127.0.0.2",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.2",
+					},
+				},
+				{
+					Service: &api.AgentService{
+						Service: "bar",
+						Address: "127.0.0.2",
+						Port:    81,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.2",
+					},
+				},
+				{
+					Service: &api.AgentService{
+						Service: "foo",
+						Address: "127.0.0.1",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.1",
+					},
+				},
+				{
+					Service: &api.AgentService{
+						Service: "foo",
+						Address: "127.0.0.2",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.2",
+					},
+				},
+			},
+		},
+		{
+			nodes: []*api.ServiceEntry{
+				{
+					Service: &api.AgentService{
+						Service: "foo",
+						Address: "",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.2",
+					},
+				},
+				{
+					Service: &api.AgentService{
+						Service: "foo",
+						Address: "",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.1",
+					},
+				},
+			},
+			expected: []*api.ServiceEntry{
+				{
+					Service: &api.AgentService{
+						Service: "foo",
+						Address: "",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.1",
+					},
+				},
+				{
+					Service: &api.AgentService{
+						Service: "foo",
+						Address: "",
+						Port:    80,
+					},
+					Node: &api.Node{
+						Node:    "localhost",
+						Address: "127.0.0.2",
+					},
+				},
+			},
+		},
+	}
+
+	for _, c := range cases {
+		sort.Sort(nodeSorter(c.nodes))
+		actual := c.nodes
+		if !reflect.DeepEqual(actual, c.expected) {
+			t.Fatalf("expected %q, got %q", c.expected, actual)
+		}
+	}
+}