server: initialize mgw-wanfed to use local gateways more on startup (#9528)

Fixes #9342

.changelog/9528.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+server: When wan federating via mesh gateways after initial federation default to using the local mesh gateways unless the heuristic indicates a bypass is required.
+```

agent/agent_test.go

@@ -4696,6 +4696,7 @@ func TestAgent_JoinWAN_viaMeshGateway(t *testing.T) {
 		}
 		# wanfed
 		primary_gateways = ["` + gwAddr + `"]
+		retry_interval_wan = "250ms"
 		connect {
 			enabled = true
 			enable_mesh_gateway_wan_federation = true
@@ -4721,6 +4722,7 @@ func TestAgent_JoinWAN_viaMeshGateway(t *testing.T) {
 		}
 		# wanfed
 		primary_gateways = ["` + gwAddr + `"]
+		retry_interval_wan = "250ms"
 		connect {
 			enabled = true
 			enable_mesh_gateway_wan_federation = true

agent/consul/gateway_locator.go

@@ -46,6 +46,7 @@ type GatewayLocator struct {
 	gatewaysLock      sync.Mutex
 	primaryGateways   []string // WAN addrs
 	localGateways     []string // LAN addrs
+	populatedGateways bool
 
 	// primaryMeshGatewayDiscoveredAddresses is the current fallback addresses
 	// for the mesh gateways in the primary datacenter.
@@ -205,6 +206,10 @@ func (g *GatewayLocator) listGateways(primary bool) []string {
 	g.gatewaysLock.Lock()
 	defer g.gatewaysLock.Unlock()
 
+	if !g.populatedGateways {
+		return nil // don't even do anything yet
+	}
+
 	var addrs []string
 	if primary {
 		if g.datacenter == g.primaryDatacenter {
@@ -267,6 +272,7 @@ type serverDelegate interface {
 	blockingQuery(queryOpts structs.QueryOptionsCompat, queryMeta structs.QueryMetaCompat, fn queryFn) error
 	IsLeader() bool
 	LeaderLastContact() time.Time
+	setDatacenterSupportsFederationStates()
 }
 
 func NewGatewayLocator(
@@ -283,6 +289,8 @@ func NewGatewayLocator(
 		primaryGatewaysReadyCh: make(chan struct{}),
 	}
 	g.logPrimaryDialingMessage(g.DialPrimaryThroughLocalGateway())
+	// initialize
+	g.SetLastFederationStateReplicationError(nil, false)
 	return g
 }
 
@@ -292,7 +300,10 @@ func (g *GatewayLocator) Run(ctx context.Context) {
 	var lastFetchIndex uint64
 	retryLoopBackoff(ctx, func() error {
 		idx, err := g.runOnce(lastFetchIndex)
-		if err != nil {
+		if errors.Is(err, errGatewayLocalStateNotInitialized) {
+			// don't do exponential backoff for something that's not broken
+			return nil
+		} else if err != nil {
 			return err
 		}
 
@@ -300,9 +311,7 @@ func (g *GatewayLocator) Run(ctx context.Context) {
 
 		return nil
 	}, func(err error) {
-		if !errors.Is(err, errGatewayLocalStateNotInitialized) {
 		g.logger.Error("error tracking primary and local mesh gateways", "error", err)
-		}
 	})
 }
 
@@ -367,6 +376,10 @@ func (g *GatewayLocator) checkLocalStateIsReady() error {
 }
 
 func (g *GatewayLocator) updateFromState(results []*structs.FederationState) {
+	if len(results) > 0 {
+		g.srv.setDatacenterSupportsFederationStates()
+	}
+
 	var (
 		local   structs.CheckServiceNodes
 		primary structs.CheckServiceNodes
@@ -388,6 +401,8 @@ func (g *GatewayLocator) updateFromState(results []*structs.FederationState) {
 	g.gatewaysLock.Lock()
 	defer g.gatewaysLock.Unlock()
 
+	g.populatedGateways = true
+
 	changed := false
 	primaryReady := false
 	if !stringslice.Equal(g.primaryGateways, primaryAddrs) {

agent/consul/gateway_locator_test.go

@@ -2,6 +2,7 @@ package consul
 
 import (
 	"errors"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -64,13 +65,25 @@ func TestGatewayLocator(t *testing.T) {
 				)
 				g.SetUseReplicationSignal(isLeader)
 
+				t.Run("before first run", func(t *testing.T) {
+					assert.False(t, g.DialPrimaryThroughLocalGateway()) // not important
+					assert.Len(t, tsd.Calls, 0)
+					assert.Equal(t, []string(nil), g.listGateways(false))
+					assert.Equal(t, []string(nil), g.listGateways(true))
+					assert.False(t, tsd.datacenterSupportsFederationStates())
+				})
+
 				idx, err := g.runOnce(0)
 				require.NoError(t, err)
-				assert.False(t, g.DialPrimaryThroughLocalGateway())
 				assert.Equal(t, uint64(1), idx)
+
+				t.Run("after first run", func(t *testing.T) {
+					assert.False(t, g.DialPrimaryThroughLocalGateway()) // not important
 					assert.Len(t, tsd.Calls, 1)
 					assert.Equal(t, []string(nil), g.listGateways(false))
 					assert.Equal(t, []string(nil), g.listGateways(true))
+					assert.False(t, tsd.datacenterSupportsFederationStates()) // no results, so we don't flip the bit yet
+				})
 			})
 		}
 	})
@@ -93,17 +106,25 @@ func TestGatewayLocator(t *testing.T) {
 				)
 				g.SetUseReplicationSignal(isLeader)
 
+				t.Run("before first run", func(t *testing.T) {
+					assert.True(t, g.DialPrimaryThroughLocalGateway()) // defaults to sure!
+					assert.Len(t, tsd.Calls, 0)
+					assert.Equal(t, []string(nil), g.listGateways(false))
+					assert.Equal(t, []string(nil), g.listGateways(true))
+					assert.False(t, tsd.datacenterSupportsFederationStates())
+				})
+
 				idx, err := g.runOnce(0)
 				require.NoError(t, err)
-				if isLeader {
-					assert.False(t, g.DialPrimaryThroughLocalGateway())
-				} else {
-					assert.True(t, g.DialPrimaryThroughLocalGateway())
-				}
 				assert.Equal(t, uint64(1), idx)
+
+				t.Run("after first run", func(t *testing.T) {
+					assert.True(t, g.DialPrimaryThroughLocalGateway()) // defaults to sure!
 					assert.Len(t, tsd.Calls, 1)
 					assert.Equal(t, []string(nil), g.listGateways(false))
 					assert.Equal(t, []string(nil), g.listGateways(true))
+					assert.False(t, tsd.datacenterSupportsFederationStates()) // no results, so we don't flip the bit yet
+				})
 			})
 		}
 	})
@@ -130,20 +151,28 @@ func TestGatewayLocator(t *testing.T) {
 					"8.8.8.8:8888",
 				})
 
+				t.Run("before first run", func(t *testing.T) {
+					assert.True(t, g.DialPrimaryThroughLocalGateway()) // defaults to sure!
+					assert.Len(t, tsd.Calls, 0)
+					assert.Equal(t, []string(nil), g.listGateways(false))
+					assert.Equal(t, []string(nil), g.listGateways(true)) // don't return any data until we initialize
+					assert.False(t, tsd.datacenterSupportsFederationStates())
+				})
+
 				idx, err := g.runOnce(0)
 				require.NoError(t, err)
-				if isLeader {
-					assert.False(t, g.DialPrimaryThroughLocalGateway())
-				} else {
-					assert.True(t, g.DialPrimaryThroughLocalGateway())
-				}
 				assert.Equal(t, uint64(1), idx)
+
+				t.Run("after first run", func(t *testing.T) {
+					assert.True(t, g.DialPrimaryThroughLocalGateway()) // defaults to sure!
 					assert.Len(t, tsd.Calls, 1)
 					assert.Equal(t, []string(nil), g.listGateways(false))
 					assert.Equal(t, []string{
 						"7.7.7.7:7777",
 						"8.8.8.8:8888",
 					}, g.listGateways(true))
+					assert.False(t, tsd.datacenterSupportsFederationStates()) // no results, so we don't flip the bit yet
+				})
 			})
 		}
 	})
@@ -170,10 +199,20 @@ func TestGatewayLocator(t *testing.T) {
 				)
 				g.SetUseReplicationSignal(isLeader)
 
+				t.Run("before first run", func(t *testing.T) {
+					assert.False(t, g.DialPrimaryThroughLocalGateway()) // not important
+					assert.Len(t, tsd.Calls, 0)
+					assert.Equal(t, []string(nil), g.listGateways(false))
+					assert.Equal(t, []string(nil), g.listGateways(true)) // don't return any data until we initialize
+					assert.False(t, tsd.datacenterSupportsFederationStates())
+				})
+
 				idx, err := g.runOnce(0)
 				require.NoError(t, err)
-				assert.False(t, g.DialPrimaryThroughLocalGateway())
 				assert.Equal(t, uint64(2), idx)
+
+				t.Run("after first run", func(t *testing.T) {
+					assert.False(t, g.DialPrimaryThroughLocalGateway()) // not important
 					assert.Len(t, tsd.Calls, 1)
 					assert.Equal(t, []string{
 						"1.2.3.4:5555",
@@ -183,6 +222,8 @@ func TestGatewayLocator(t *testing.T) {
 						"1.2.3.4:5555",
 						"4.3.2.1:9999",
 					}, g.listGateways(true))
+					assert.True(t, tsd.datacenterSupportsFederationStates()) // have results, so we flip the bit
+				})
 			})
 		}
 	})
@@ -205,66 +246,34 @@ func TestGatewayLocator(t *testing.T) {
 				)
 				g.SetUseReplicationSignal(isLeader)
 
-				idx, err := g.runOnce(0)
+				t.Run("before first run", func(t *testing.T) {
-				require.NoError(t, err)
+					assert.True(t, g.DialPrimaryThroughLocalGateway()) // defaults to sure!
-				if isLeader {
+					assert.Len(t, tsd.Calls, 0)
-					assert.False(t, g.DialPrimaryThroughLocalGateway())
+					assert.Equal(t, []string(nil), g.listGateways(false))
-				} else {
+					assert.Equal(t, []string(nil), g.listGateways(true)) // don't return any data until we initialize
-					assert.True(t, g.DialPrimaryThroughLocalGateway())
+					assert.False(t, tsd.datacenterSupportsFederationStates())
-				}
-				assert.Equal(t, uint64(2), idx)
-				assert.Len(t, tsd.Calls, 1)
-				assert.Equal(t, []string{
-					"5.6.7.8:5555",
-					"8.7.6.5:9999",
-				}, g.listGateways(false))
-				if isLeader {
-					assert.Equal(t, []string{
-						"1.2.3.4:5555",
-						"4.3.2.1:9999",
-					}, g.listGateways(true))
-				} else {
-					assert.Equal(t, []string{
-						"5.6.7.8:5555",
-						"8.7.6.5:9999",
-					}, g.listGateways(true))
-				}
-			})
-		}
-	})
-
-	t.Run("secondary - with data and fallback - no repl", func(t *testing.T) {
-		// Only run for the leader.
-		logger := testutil.Logger(t)
-		tsd := &testServerDelegate{State: state, isLeader: true}
-		g := NewGatewayLocator(
-			logger,
-			tsd,
-			"dc2",
-			"dc1",
-		)
-		g.SetUseReplicationSignal(true)
-
-		g.RefreshPrimaryGatewayFallbackAddresses([]string{
-			"7.7.7.7:7777",
-			"8.8.8.8:8888",
 				})
 
 				idx, err := g.runOnce(0)
 				require.NoError(t, err)
-		assert.False(t, g.DialPrimaryThroughLocalGateway())
 				assert.Equal(t, uint64(2), idx)
+
+				t.Run("after first run", func(t *testing.T) {
+					assert.True(t, g.DialPrimaryThroughLocalGateway()) // defaults to sure!
 					assert.Len(t, tsd.Calls, 1)
 					assert.Equal(t, []string{
 						"5.6.7.8:5555",
 						"8.7.6.5:9999",
 					}, g.listGateways(false))
 					assert.Equal(t, []string{
-			"1.2.3.4:5555",
+						"5.6.7.8:5555",
-			"4.3.2.1:9999",
+						"8.7.6.5:9999",
-			"7.7.7.7:7777",
-			"8.8.8.8:8888",
 					}, g.listGateways(true))
+					assert.True(t, tsd.datacenterSupportsFederationStates()) // have results, so we flip the bit
+				})
+
+			})
+		}
 	})
 
 	t.Run("secondary - with data and fallback - repl ok", func(t *testing.T) {
@@ -286,10 +295,20 @@ func TestGatewayLocator(t *testing.T) {
 
 		g.SetLastFederationStateReplicationError(nil, true)
 
+		t.Run("before first run", func(t *testing.T) {
+			assert.True(t, g.DialPrimaryThroughLocalGateway()) // defaults to sure!
+			assert.Len(t, tsd.Calls, 0)
+			assert.Equal(t, []string(nil), g.listGateways(false))
+			assert.Equal(t, []string(nil), g.listGateways(true)) // don't return any data until we initialize
+			assert.False(t, tsd.datacenterSupportsFederationStates())
+		})
+
 		idx, err := g.runOnce(0)
 		require.NoError(t, err)
-		assert.True(t, g.DialPrimaryThroughLocalGateway())
 		assert.Equal(t, uint64(2), idx)
+
+		t.Run("after first run", func(t *testing.T) {
+			assert.True(t, g.DialPrimaryThroughLocalGateway())
 			assert.Len(t, tsd.Calls, 1)
 			assert.Equal(t, []string{
 				"5.6.7.8:5555",
@@ -299,6 +318,8 @@ func TestGatewayLocator(t *testing.T) {
 				"5.6.7.8:5555",
 				"8.7.6.5:9999",
 			}, g.listGateways(true))
+			assert.True(t, tsd.datacenterSupportsFederationStates()) // have results, so we flip the bit
+		})
 	})
 
 	t.Run("secondary - with data and fallback - repl ok then failed 2 times", func(t *testing.T) {
@@ -322,10 +343,20 @@ func TestGatewayLocator(t *testing.T) {
 		g.SetLastFederationStateReplicationError(errors.New("fake"), true)
 		g.SetLastFederationStateReplicationError(errors.New("fake"), true)
 
+		t.Run("before first run", func(t *testing.T) {
+			assert.True(t, g.DialPrimaryThroughLocalGateway()) // defaults to sure!
+			assert.Len(t, tsd.Calls, 0)
+			assert.Equal(t, []string(nil), g.listGateways(false))
+			assert.Equal(t, []string(nil), g.listGateways(true)) // don't return any data until we initialize
+			assert.False(t, tsd.datacenterSupportsFederationStates())
+		})
+
 		idx, err := g.runOnce(0)
 		require.NoError(t, err)
-		assert.True(t, g.DialPrimaryThroughLocalGateway())
 		assert.Equal(t, uint64(2), idx)
+
+		t.Run("after first run", func(t *testing.T) {
+			assert.True(t, g.DialPrimaryThroughLocalGateway())
 			assert.Len(t, tsd.Calls, 1)
 			assert.Equal(t, []string{
 				"5.6.7.8:5555",
@@ -335,6 +366,8 @@ func TestGatewayLocator(t *testing.T) {
 				"5.6.7.8:5555",
 				"8.7.6.5:9999",
 			}, g.listGateways(true))
+			assert.True(t, tsd.datacenterSupportsFederationStates()) // have results, so we flip the bit
+		})
 	})
 
 	t.Run("secondary - with data and fallback - repl ok then failed 3 times", func(t *testing.T) {
@@ -359,10 +392,20 @@ func TestGatewayLocator(t *testing.T) {
 		g.SetLastFederationStateReplicationError(errors.New("fake"), true)
 		g.SetLastFederationStateReplicationError(errors.New("fake"), true)
 
+		t.Run("before first run", func(t *testing.T) {
+			assert.False(t, g.DialPrimaryThroughLocalGateway()) // too many errors
+			assert.Len(t, tsd.Calls, 0)
+			assert.Equal(t, []string(nil), g.listGateways(false))
+			assert.Equal(t, []string(nil), g.listGateways(true)) // don't return any data until we initialize
+			assert.False(t, tsd.datacenterSupportsFederationStates())
+		})
+
 		idx, err := g.runOnce(0)
 		require.NoError(t, err)
-		assert.False(t, g.DialPrimaryThroughLocalGateway())
 		assert.Equal(t, uint64(2), idx)
+
+		t.Run("after first run", func(t *testing.T) {
+			assert.False(t, g.DialPrimaryThroughLocalGateway())
 			assert.Len(t, tsd.Calls, 1)
 			assert.Equal(t, []string{
 				"5.6.7.8:5555",
@@ -374,6 +417,8 @@ func TestGatewayLocator(t *testing.T) {
 				"7.7.7.7:7777",
 				"8.8.8.8:8888",
 			}, g.listGateways(true))
+			assert.True(t, tsd.datacenterSupportsFederationStates()) // have results, so we flip the bit
+		})
 	})
 
 	t.Run("secondary - with data and fallback - repl ok then failed 3 times then ok again", func(t *testing.T) {
@@ -399,10 +444,20 @@ func TestGatewayLocator(t *testing.T) {
 		g.SetLastFederationStateReplicationError(errors.New("fake"), true)
 		g.SetLastFederationStateReplicationError(nil, true)
 
+		t.Run("before first run", func(t *testing.T) {
+			assert.True(t, g.DialPrimaryThroughLocalGateway()) // all better again
+			assert.Len(t, tsd.Calls, 0)
+			assert.Equal(t, []string(nil), g.listGateways(false))
+			assert.Equal(t, []string(nil), g.listGateways(true)) // don't return any data until we initialize
+			assert.False(t, tsd.datacenterSupportsFederationStates())
+		})
+
 		idx, err := g.runOnce(0)
 		require.NoError(t, err)
-		assert.True(t, g.DialPrimaryThroughLocalGateway())
 		assert.Equal(t, uint64(2), idx)
+
+		t.Run("after first run", func(t *testing.T) {
+			assert.True(t, g.DialPrimaryThroughLocalGateway()) // all better again
 			assert.Len(t, tsd.Calls, 1)
 			assert.Equal(t, []string{
 				"5.6.7.8:5555",
@@ -412,10 +467,14 @@ func TestGatewayLocator(t *testing.T) {
 				"5.6.7.8:5555",
 				"8.7.6.5:9999",
 			}, g.listGateways(true))
+			assert.True(t, tsd.datacenterSupportsFederationStates()) // have results, so we flip the bit
+		})
 	})
 }
 
 type testServerDelegate struct {
+	dcSupportsFederationStates int32 // atomically accessed, at start to prevent alignment issues
+
 	State *state.Store
 
 	Calls []uint64
@@ -424,6 +483,14 @@ type testServerDelegate struct {
 	lastContact time.Time
 }
 
+func (d *testServerDelegate) setDatacenterSupportsFederationStates() {
+	atomic.StoreInt32(&d.dcSupportsFederationStates, 1)
+}
+
+func (d *testServerDelegate) datacenterSupportsFederationStates() bool {
+	return atomic.LoadInt32(&d.dcSupportsFederationStates) != 0
+}
+
 // This is just enough to exercise the logic.
 func (d *testServerDelegate) blockingQuery(
 	queryOpts structs.QueryOptionsCompat,