agent: working DNS for Connect queries, I think, but have to

implement Health endpoints to be sure

agent/dns.go

@@ -337,7 +337,7 @@ func (d *DNSServer) addSOA(msg *dns.Msg) {
 // nameservers returns the names and ip addresses of up to three random servers
 // in the current cluster which serve as authoritative name servers for zone.
 func (d *DNSServer) nameservers(edns bool) (ns []dns.RR, extra []dns.RR) {
-	out, err := d.lookupServiceNodes(d.agent.config.Datacenter, structs.ConsulServiceName, "")
+	out, err := d.lookupServiceNodes(d.agent.config.Datacenter, structs.ConsulServiceName, "", false)
 	if err != nil {
 		d.logger.Printf("[WARN] dns: Unable to get list of servers: %s", err)
 		return nil, nil
@@ -415,7 +415,7 @@ PARSE:
 		n = n + 1
 	}
 
-	switch labels[n-1] {
+	switch kind := labels[n-1]; kind {
 	case "service":
 		if n == 1 {
 			goto INVALID
@@ -433,7 +433,7 @@ PARSE:
 			}
 
 			// _name._tag.service.consul
-			d.serviceLookup(network, datacenter, labels[n-3][1:], tag, req, resp)
+			d.serviceLookup(network, datacenter, labels[n-3][1:], tag, false, req, resp)
 
 			// Consul 0.3 and prior format for SRV queries
 		} else {
@@ -445,9 +445,17 @@ PARSE:
 			}
 
 			// tag[.tag].name.service.consul
-			d.serviceLookup(network, datacenter, labels[n-2], tag, req, resp)
+			d.serviceLookup(network, datacenter, labels[n-2], tag, false, req, resp)
 		}
 
+	case "connect":
+		if n == 1 {
+			goto INVALID
+		}
+
+		// name.connect.consul
+		d.serviceLookup(network, datacenter, labels[n-2], "", true, req, resp)
+
 	case "node":
 		if n == 1 {
 			goto INVALID
@@ -898,8 +906,9 @@ func (d *DNSServer) trimDNSResponse(network string, req, resp *dns.Msg) (trimmed
 }
 
 // lookupServiceNodes returns nodes with a given service.
-func (d *DNSServer) lookupServiceNodes(datacenter, service, tag string) (structs.IndexedCheckServiceNodes, error) {
+func (d *DNSServer) lookupServiceNodes(datacenter, service, tag string, connect bool) (structs.IndexedCheckServiceNodes, error) {
 	args := structs.ServiceSpecificRequest{
+		Connect:     connect,
 		Datacenter:  datacenter,
 		ServiceName: service,
 		ServiceTag:  tag,
@@ -935,8 +944,8 @@ func (d *DNSServer) lookupServiceNodes(datacenter, service, tag string) (structs
 }
 
 // serviceLookup is used to handle a service query
-func (d *DNSServer) serviceLookup(network, datacenter, service, tag string, req, resp *dns.Msg) {
+func (d *DNSServer) serviceLookup(network, datacenter, service, tag string, connect bool, req, resp *dns.Msg) {
-	out, err := d.lookupServiceNodes(datacenter, service, tag)
+	out, err := d.lookupServiceNodes(datacenter, service, tag, connect)
 	if err != nil {
 		d.logger.Printf("[ERR] dns: rpc error: %v", err)
 		resp.SetRcode(req, dns.RcodeServerFailure)

agent/dns_test.go

@@ -17,6 +17,7 @@ import (
 	"github.com/hashicorp/serf/coordinate"
 	"github.com/miekg/dns"
 	"github.com/pascaldekloe/goe/verify"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -1041,6 +1042,48 @@ func TestDNS_ServiceLookupWithInternalServiceAddress(t *testing.T) {
 	verify.Values(t, "extra", in.Extra, wantExtra)
 }
 
+func TestDNS_ConnectServiceLookup(t *testing.T) {
+	t.Parallel()
+
+	assert := assert.New(t)
+	a := NewTestAgent(t.Name(), "")
+	defer a.Shutdown()
+
+	// Register a node with an external service.
+	{
+		args := structs.TestRegisterRequestProxy(t)
+		args.Service.ProxyDestination = "db"
+		args.Service.Port = 12345
+		var out struct{}
+		assert.Nil(a.RPC("Catalog.Register", args, &out))
+	}
+
+	// Look up the service
+	questions := []string{
+		"db.connect.consul.",
+	}
+	for _, question := range questions {
+		m := new(dns.Msg)
+		m.SetQuestion(question, dns.TypeSRV)
+
+		c := new(dns.Client)
+		in, _, err := c.Exchange(m, a.DNSAddr())
+		assert.Nil(err)
+		assert.Len(in.Answer, 1)
+
+		srvRec, ok := in.Answer[0].(*dns.SRV)
+		assert.True(ok)
+		assert.Equal(12345, srvRec.Port)
+		assert.Equal("foo.node.dc1.consul.", srvRec.Target)
+		assert.Equal(0, srvRec.Hdr.Ttl)
+
+		cnameRec, ok := in.Extra[0].(*dns.CNAME)
+		assert.True(ok)
+		assert.Equal("foo.node.dc1.consul.", cnameRec.Hdr.Name)
+		assert.Equal(0, srvRec.Hdr.Ttl)
+	}
+}
+
 func TestDNS_ExternalServiceLookup(t *testing.T) {
 	t.Parallel()
 	a := NewTestAgent(t.Name(), "")