TUN-4927: Parameterize region in edge discovery code

Author: sssilver

edgediscovery/allregions/discovery.go

@@ -22,6 +22,8 @@ const (
 	dotServerName = "cloudflare-dns.com"
 	dotServerAddr = "1.1.1.1:853"
 	dotTimeout    = 15 * time.Second
+
+	logFieldAddress = "address"
 )
 
 // Redeclare network functions so they can be overridden in tests.
@@ -59,7 +61,9 @@ var friendlyDNSErrorLines = []string{
 }
 
 // EdgeDiscovery implements HA service discovery lookup.
-func edgeDiscovery(log *zerolog.Logger) ([][]*EdgeAddr, error) {
+func edgeDiscovery(log *zerolog.Logger, srvService string) ([][]*EdgeAddr, error) {
+	log.Debug().Str("domain", "_"+srvService+"._"+srvProto+"."+srvName).Msg("looking up edge SRV record")
+
 	_, addrs, err := netLookupSRV(srvService, srvProto, srvName)
 	if err != nil {
 		_, fallbackAddrs, fallbackErr := fallbackLookupSRV(srvService, srvProto, srvName)
@@ -87,7 +91,7 @@ func edgeDiscovery(log *zerolog.Logger) ([][]*EdgeAddr, error) {
 	return resolvedAddrPerCNAME, nil
 }
 
-func lookupSRVWithDOT(service, proto, name string) (cname string, addrs []*net.SRV, err error) {
+func lookupSRVWithDOT(string, string, string) (cname string, addrs []*net.SRV, err error) {
 	// Inspiration: https://github.com/artyom/dot/blob/master/dot.go
 	r := &net.Resolver{
 		PreferGo: true,
@@ -130,13 +134,13 @@ func ResolveAddrs(addrs []string, log *zerolog.Logger) (resolved []*EdgeAddr) {
 	for _, addr := range addrs {
 		tcpAddr, err := net.ResolveTCPAddr("tcp", addr)
 		if err != nil {
-			log.Error().Msgf("Failed to resolve %s to TCP address, err: %v", addr, err)
+			log.Error().Str(logFieldAddress, addr).Err(err).Msg("failed to resolve to TCP address")
 			continue
 		}
 
 		udpAddr, err := net.ResolveUDPAddr("udp", addr)
 		if err != nil {
-			log.Error().Msgf("Failed to resolve %s to UDP address, err: %v", addr, err)
+			log.Error().Str(logFieldAddress, addr).Err(err).Msg("failed to resolve to UDP address")
 			continue
 		}
 		resolved = append(resolved, &EdgeAddr{

edgediscovery/allregions/discovery_test.go

@@ -25,7 +25,7 @@ func TestEdgeDiscovery(t *testing.T) {
 	}
 
 	l := zerolog.Nop()
-	addrLists, err := edgeDiscovery(&l)
+	addrLists, err := edgeDiscovery(&l, "")
 	assert.NoError(t, err)
 	actualAddrSet := map[string]bool{}
 	for _, addrs := range addrLists {

edgediscovery/allregions/regions.go

@@ -18,8 +18,8 @@ type Regions struct {
 // ------------------------------------
 
 // ResolveEdge resolves the Cloudflare edge, returning all regions discovered.
-func ResolveEdge(log *zerolog.Logger) (*Regions, error) {
-	edgeAddrs, err := edgeDiscovery(log)
+func ResolveEdge(log *zerolog.Logger, region string) (*Regions, error) {
+	edgeAddrs, err := edgeDiscovery(log, getRegionalServiceName(region))
 	if err != nil {
 		return nil, err
 	}
@@ -122,3 +122,12 @@ func (rs *Regions) GiveBack(addr *EdgeAddr) bool {
 	}
 	return rs.region2.GiveBack(addr)
 }
+
+// Return regionalized service name if `region` isn't empty, otherwise return the global service name for origintunneld
+func getRegionalServiceName(region string) string {
+	if region != "" {
+		return region + "-" + srvService // Example: `us-origintunneld`
+	}
+
+	return srvService // Global service is just `origintunneld`
+}

edgediscovery/allregions/regions_test.go

@@ -156,6 +156,18 @@ func TestNewNoResolveBalancesRegions(t *testing.T) {
 	}
 }
 
+func TestGetRegionalServiceName(t *testing.T) {
+	// Empty region should just go to origintunneld
+	globalServiceName := getRegionalServiceName("")
+	assert.Equal(t, srvService, globalServiceName)
+
+	// Non-empty region should go to the regional origintunneld variant
+	for _, region := range []string{"us", "pt", "am"} {
+		regionalServiceName := getRegionalServiceName(region)
+		assert.Equal(t, region+"-"+srvService, regionalServiceName)
+	}
+}
+
 func RegionsIsBalanced(t *testing.T, rs *Regions) {
 	delta := rs.region1.AvailableAddrs() - rs.region2.AvailableAddrs()
 	assert.True(t, abs(delta) <= 1)

edgediscovery/edgediscovery.go

@@ -30,8 +30,8 @@ type Edge struct {
 
 // ResolveEdge runs the initial discovery of the Cloudflare edge, finding Addrs that can be allocated
 // to connections.
-func ResolveEdge(log *zerolog.Logger) (*Edge, error) {
-	regions, err := allregions.ResolveEdge(log)
+func ResolveEdge(log *zerolog.Logger, region string) (*Edge, error) {
+	regions, err := allregions.ResolveEdge(log, region)
 	if err != nil {
 		return new(Edge), err
 	}

origin/supervisor.go

@@ -74,7 +74,7 @@ func NewSupervisor(config *TunnelConfig, reconnectCh chan ReconnectSignal, grace
 	if len(config.EdgeAddrs) > 0 {
 		edgeIPs, err = edgediscovery.StaticEdge(config.Log, config.EdgeAddrs)
 	} else {
-		edgeIPs, err = edgediscovery.ResolveEdge(config.Log)
+		edgeIPs, err = edgediscovery.ResolveEdge(config.Log, "")
 	}
 	if err != nil {
 		return nil, err