More grpc LB tweaks

Signed-off-by: Miek Gieben <miek@miek.nl>

2 files changed, 17 insertions, 8 deletions

diff --git a/plugin/traffic/grpc_lb.go b/plugin/traffic/grpc_lb.go
index 7205caea3..2b27d20a3 100644
--- a/plugin/traffic/grpc_lb.go
+++ b/plugin/traffic/grpc_lb.go
@@ -1,16 +1,19 @@
 package traffic
 
 import (
+	"fmt"
+
 	"github.com/miekg/dns"
 )
 
 // See https://github.com/grpc/grpc/blob/master/doc/service_config.md for the fields in this proto.
 // We encode it as json and return it in a TXT field.
-var lbTXT = `grpc_config=[{"serviceConfig":{"loadBalancingConfig":[{"eds_experimental":{"LrsLoadReportingServerName":"","Cluster": "xds"}}]}}]`
+// TOOD(miek): balancer name should not be hardcoded
+var lbTXT = `grpc_config=[{"serviceConfig":{"loadBalancingConfig":[{"eds_experimental":{"Cluster": "xds", "EDSServiceName":"%s", "BalancerName":"xds"}}]}}]`
 
-func txt(z string) []dns.RR {
+func txt(z, cluster string) []dns.RR {
 	return []dns.RR{&dns.TXT{
 		Hdr: dns.RR_Header{Name: z, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: 5},
-		Txt: []string{lbTXT},
+		Txt: []string{fmt.Sprintf(lbTXT, cluster)},
 	}}
 }
diff --git a/plugin/traffic/traffic.go b/plugin/traffic/traffic.go
index 8f4f1606d..fbc57d101 100644
--- a/plugin/traffic/traffic.go
+++ b/plugin/traffic/traffic.go
@@ -70,7 +70,7 @@ func (t *Traffic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
 			}
 			if strings.HasPrefix(strings.ToLower(labels[0]), "_grpc_config") {
 				// this is the grpc config blob encoded in a TXT record, see documentation for lbTXT.
-				m.Answer = txt(state.Zone)
+				m.Answer = txt(state.Zone, labels[1]) // 1 is the cluster
 				m.Rcode = dns.RcodeSuccess
 				w.WriteMsg(m)
 				return 0, nil
@@ -95,10 +95,16 @@ func (t *Traffic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
 				w.WriteMsg(m)
 				return 0, nil
 			}
-			// OK, _grcplb._tcp query; we need to return the endpoint for the mgmt cluster *NOT* the cluster
-			// we got the query for. This should exist, but we'll check later anyway.
-			cluster = t.mgmt
-			sockaddr, _ = t.c.Select(cluster, healthy)
+			// OK, _grcplb._tcp query; we need to return the endpoint for the cluster in this query
+			cluster = labels[2]
+			sockaddr, ok = t.c.Select(cluster, healthy)
+			if !ok {
+				// nodata error when this cluster doesn't exist.
+				m.Ns = soa(state.Zone)
+				m.Rcode = dns.RcodeSuccess
+				w.WriteMsg(m)
+				return 0, nil
+			}
 			break
 		default:
 			m.Ns = soa(state.Zone)