Correctly re-establish the stream

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

plugin/traffic/setup.go

@@ -38,7 +38,26 @@ func setup(c *caddy.Controller) error {
 	})
 
 	c.OnStartup(func() error {
-		go t.c.Run()
+		go func() {
+			for {
+				opts := []grpc.DialOption{grpc.WithInsecure()}
+				if t.tlsConfig != nil {
+					opts = []grpc.DialOption{grpc.WithTransportCredentials(credentials.NewTLS(t.tlsConfig))}
+				}
+
+			redo:
+
+				t.c, err = xds.New(t.hosts[0], t.node, opts...)
+				err := t.c.Run()
+				if err != nil {
+					log.Warning(err)
+					time.Sleep(2 * time.Second) // back off foo
+					goto redo
+				}
+				// err == nil
+				break
+			}
+		}()
 		metrics.MustRegister(c, xds.ClusterGauge)
 		return nil
 	})
@@ -47,9 +66,8 @@ func setup(c *caddy.Controller) error {
 }
 
 func parseTraffic(c *caddy.Controller) (*Traffic, error) {
-	node := "coredns"
 	toHosts := []string{}
-	t := &Traffic{}
+	t := &Traffic{node: "coredns"}
 	var (
 		err           error
 		tlsConfig     *tls.Config
@@ -85,7 +103,7 @@ func parseTraffic(c *caddy.Controller) (*Traffic, error) {
 				if len(args) != 1 {
 					return nil, c.ArgErr()
 				}
-				node = args[0]
+				t.node = args[0]
 			case "tls":
 				args := c.RemainingArgs()
 				if len(args) > 3 {
@@ -109,19 +127,13 @@ func parseTraffic(c *caddy.Controller) (*Traffic, error) {
 		}
 	}
 
-	opts := []grpc.DialOption{grpc.WithInsecure()}
 	if tlsConfig != nil {
+		t.tlsConfig = tlsConfig
 		if tlsServerName != "" {
-			tlsConfig.ServerName = tlsServerName
+			t.tlsConfig.ServerName = tlsServerName
 		}
-		opts = []grpc.DialOption{grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig))}
 	}
-
-	// TODO: only the first host is used, need to figure out how to reconcile multiple upstream providers.
-	if t.c, err = xds.New(toHosts[0], node, opts...); err != nil {
-		return nil, err
-	}
-
+	t.hosts = toHosts
 	return t, nil
 }
 

plugin/traffic/traffic.go

@@ -2,6 +2,7 @@ package traffic
 
 import (
 	"context"
+	"crypto/tls"
 	"fmt"
 	"strconv"
 	"strings"
@@ -18,6 +19,10 @@ import (
 // Traffic is a plugin that load balances according to assignments.
 type Traffic struct {
 	c         *xds.Client
+	node      string
+	tlsConfig *tls.Config
+	hosts     []string
+
 	id      string
 	health  bool
 	origins []string

plugin/traffic/xds/client.go

@@ -24,7 +24,6 @@ import (
 	"context"
 	"fmt"
 	"sync"
-	"time"
 
 	"github.com/coredns/coredns/coremain"
 	clog "github.com/coredns/coredns/plugin/pkg/log"
@@ -79,21 +78,19 @@ func New(addr, node string, opts ...grpc.DialOption) (*Client, error) {
 func (c *Client) Stop() error { c.cancel(); return c.cc.Close() }
 
 // Run starts all goroutines and gathers the clusters and endpoint information from the upstream manager.
-func (c *Client) Run() {
+func (c *Client) Run() error {
 	first := true
 	for {
 		select {
 		case <-c.ctx.Done():
-			return
+			return nil
 		default:
 		}
 
 		cli := xdspb.NewAggregatedDiscoveryServiceClient(c.cc)
 		stream, err := cli.StreamAggregatedResources(c.ctx)
 		if err != nil {
-			log.Debug(err)
-			time.Sleep(2 * time.Second) // grpc's client.go does more spiffy exp. backoff, do we really need that?
-			continue
+			return err
 		}
 
 		if first {
@@ -107,7 +104,7 @@ func (c *Client) Run() {
 		}
 
 		if err := c.receive(stream); err != nil {
-			log.Warning(err)
+			return err
 		}
 	}
 }