fix dynamic update of the default backend

Since v0.11, all cluster updates try to be partially applied in the
in-memory model. This is addressed building an object tracking, followed
by purging the old state and recreating these same objects in the new
state. In short ingress objects track hostnames, services and secrets,
and services track endpoints.

Default backends wasn't being updated because it exposes a service
without using an ingress object, so endpoints are deployed on a full
synchronization, including de first one, and wasn't tracker anymore.
This update creates a dummy tracking point to bind the default backend
endpoints and the haproxy model.

This update also needed to manage an issue with the backend ID: the
default backend is renamed to `_default_backend` when assigned as such,
and changed back when unassiged. This unassignment happens when the
backend is purged in order to have its internal state updated, and such
asynchrony should be fixed in the dynupdate. Now dynupdate compares
backends based on an internal and immutable state.

pkg/converters/ingress/ingress.go

@@ -65,6 +65,7 @@ func NewIngressConverter(options *ingtypes.ConverterOptions, haproxy haproxy.Con
 		logger:             options.Logger,
 		cache:              options.Cache,
 		tracker:            options.Tracker,
+		defaultBackSource:  annotations.Source{Name: "<default-backend>", Type: "ingress"},
 		mapBuilder:         annotations.NewMapBuilder(options.Logger, options.AnnotationPrefix+"/", defaultConfig),
 		updater:            annotations.NewUpdater(haproxy, options),
 		globalConfig:       annotations.NewMapBuilder(options.Logger, "", defaultConfig).NewMapper(),
@@ -82,6 +83,7 @@ type converter struct {
 	cache              convtypes.Cache
 	tracker            convtypes.Tracker
 	defaultCrt         convtypes.CrtFile
+	defaultBackSource  annotations.Source
 	mapBuilder         *annotations.MapBuilder
 	updater            annotations.Updater
 	globalConfig       *annotations.Mapper
@@ -95,7 +97,6 @@ func (c *converter) Sync() {
 		c.haproxy.Clear()
 	}
 	c.syncDefaultCrt()
-	c.syncDefaultBackend()
 	if c.needFullSync {
 		c.syncFull()
 	} else {
@@ -150,8 +151,9 @@ func (c *converter) syncDefaultCrt() {
 
 func (c *converter) syncDefaultBackend() {
 	if c.options.DefaultBackend != "" {
-		if backend, err := c.addBackend(&annotations.Source{}, hatypes.DefaultHost, "/", c.options.DefaultBackend, "", map[string]string{}); err == nil {
+		if backend, err := c.addBackend(&c.defaultBackSource, hatypes.DefaultHost, "/", c.options.DefaultBackend, "", map[string]string{}); err == nil {
 			c.haproxy.Backends().SetDefaultBackend(backend)
+			c.tracker.TrackHostname(convtypes.IngressType, c.defaultBackSource.FullName(), hatypes.DefaultHost)
 		} else {
 			c.logger.Error("error reading default service: %v", err)
 		}
@@ -165,6 +167,7 @@ func (c *converter) syncFull() {
 		return
 	}
 	sortIngress(ingList)
+	c.syncDefaultBackend()
 	for _, ing := range ingList {
 		c.syncIngress(ing)
 	}
@@ -266,7 +269,11 @@ func (c *converter) syncPartial() {
 			var err error
 			ing, err = c.cache.GetIngress(name)
 			if err != nil {
-				c.logger.Warn("ignoring ingress '%s': %v", name, err)
+				if name == c.defaultBackSource.FullName() {
+					c.syncDefaultBackend()
+				} else {
+					c.logger.Warn("ignoring ingress '%s': %v", name, err)
+				}
 				ing = nil
 			}
 		}

pkg/converters/ingress/ingress_test.go

@@ -1214,7 +1214,7 @@ WARN using default certificate due to an error reading secret 'default/tls1' on
 				{"default/echo1", "echo1:8080"},
 			},
 			svcAdd:          svcDefault,
-			logging:         `INFO-V(2) syncing 1 host(s) and 0 backend(s)`,
+			logging:         `INFO-V(2) syncing 1 host(s) and 1 backend(s)`,
 			expDefaultFront: expDefaultFrontDefault,
 			expBack: `
 - id: default_echo1_8080
@@ -1347,6 +1347,30 @@ WARN using default certificate due to an error reading secret 'default/tls1' on
 	}
 }
 
+func TestSyncPartialDefaultBackend(t *testing.T) {
+	c := setup(t)
+	defer c.teardown()
+
+	// first config, sync, commit, cleanup
+	c.Sync()
+	c.hconfig.Commit()
+	c.logger.Logging = []string{}
+
+	// the mock of the default backend is hardcoded to system/default:8080 at 172.17.0.99
+	_, ep := conv_helper.CreateService("system/default", "8080", "172.17.0.90")
+	c.cache.Changed.Endpoints = []*api.Endpoints{ep}
+	c.Sync()
+
+	c.compareConfigFront(`[]`)
+	c.compareConfigBack(`
+- id: _default_backend
+  endpoints:
+  - ip: 172.17.0.90
+    port: 8080
+`)
+	c.logger.CompareLogging(`INFO-V(2) syncing 1 host(s) and 1 backend(s)`)
+}
+
 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  *
  *  ANNOTATIONS

pkg/haproxy/dynupdate.go

@@ -97,12 +97,13 @@ func (d *dynUpdater) checkConfigChange() bool {
 	// return false on new backend which cannot be dynamically created
 	backends := make(map[string]*backendPair, len(d.config.backends.ItemsDel()))
 	for _, backend := range d.config.backends.ItemsDel() {
-		backends[backend.ID] = &backendPair{old: backend}
+		backends[backend.BackendID().String()] = &backendPair{old: backend}
 	}
 	for _, backend := range d.config.backends.ItemsAdd() {
-		back, found := backends[backend.ID]
+		id := backend.BackendID().String()
+		back, found := backends[id]
 		if !found {
-			d.logger.InfoV(2, "added backend '%s'", backend.ID)
+			d.logger.InfoV(2, "added backend '%s'", id)
 			updated = false
 		} else {
 			back.cur = backend
@@ -133,6 +134,7 @@ func (d *dynUpdater) checkBackendPair(pair *backendPair) bool {
 
 	// check equality of everything but endpoints
 	oldBackCopy := *oldBack
+	oldBackCopy.ID = curBack.ID
 	oldBackCopy.Dynamic = curBack.Dynamic
 	oldBackCopy.Endpoints = curBack.Endpoints
 	if !reflect.DeepEqual(&oldBackCopy, curBack) {

pkg/haproxy/dynupdate_test.go

@@ -582,6 +582,29 @@ set server default_app_8080/srv002 weight 1`,
 			},
 			dynamic: true,
 		},
+		// 23
+		{
+			doconfig1: func(c *testConfig) {
+				b := c.config.Backends().AcquireBackend("default", "app", "8080")
+				c.config.backends.SetDefaultBackend(b)
+				b.AcquireEndpoint("172.17.0.2", 8080, "")
+			},
+			doconfig2: func(c *testConfig) {
+				b := c.config.Backends().AcquireBackend("default", "app", "8080")
+				c.config.backends.SetDefaultBackend(b)
+				b.Dynamic.DynUpdate = true
+				b.AcquireEndpoint("172.17.0.3", 8080, "")
+			},
+			expected: []string{
+				"srv001:172.17.0.3:8080:1",
+			},
+			dynamic: true,
+			cmd: `
+set server _default_backend/srv001 addr 172.17.0.3 port 8080
+set server _default_backend/srv001 state ready
+set server _default_backend/srv001 weight 1`,
+			logging: `INFO-V(2) updated endpoint '172.17.0.3:8080' weight '1' state 'ready' on backend/server '_default_backend/srv001'`,
+		},
 	}
 	for i, test := range testCases {
 		c := setup(t)
@@ -591,9 +614,7 @@ set server default_app_8080/srv002 weight 1`,
 		c.instance.config.Commit()
 		backendIDs := []types.BackendID{}
 		for _, backend := range c.config.Backends().Items() {
-			if backend != c.config.Backends().DefaultBackend() {
-				backendIDs = append(backendIDs, backend.BackendID())
-			}
+			backendIDs = append(backendIDs, backend.BackendID())
 		}
 		c.config.Backends().RemoveAll(backendIDs)
 		if test.doconfig2 != nil {

pkg/haproxy/types/backends.go

@@ -230,6 +230,9 @@ func (b *Backends) RemoveAll(backendID []BackendID) {
 			}
 			b.changedShards[item.shard] = true
 			b.itemsDel[id] = item
+			if item == b.defaultBackend {
+				b.SetDefaultBackend(nil)
+			}
 			delete(b.items, id)
 		}
 	}
@@ -254,7 +257,7 @@ func (b *Backends) SetDefaultBackend(defaultBackend *Backend) {
 
 func (b BackendID) String() string {
 	if b.id == "" {
-		b.id = b.Namespace + "_" + b.Name + "_" + b.Port
+		b.id = buildID(b.Namespace, b.Name, b.Port)
 	}
 	return b.id
 }