Debug host resolution part.

Signed-off-by: Bartek Plotka <[email protected]>

pkg/kedge/http/lbtransport/transport.go

@@ -2,8 +2,10 @@ package lbtransport
 
 import (
 	"context"
+	"fmt"
 	"net"
 	"net/http"
+	"os"
 	"sync"
 
 	"github.com/improbable-eng/go-httpwares/tags"
@@ -56,12 +58,14 @@ func New(ctx context.Context, targetAddr string, parent http.RoundTripper, resol
 		currentTargets: []*Target{},
 	}
 
+	fmt.Fprintln(os.Stderr, "New watcher for target ", targetAddr)
 	watcher, err := resolver.Resolve(targetAddr)
 	if err != nil {
 		return nil, errors.Wrapf(err, "tripper: failed to do initial resolve for target %s", targetAddr)
 	}
 	go func() {
 		<-ctx.Done()
+		fmt.Fprintln(os.Stderr, "Closing watcher for target ", targetAddr)
 		watcher.Close()
 	}()
 	go s.run(ctx, watcher)
@@ -71,15 +75,18 @@ func New(ctx context.Context, targetAddr string, parent http.RoundTripper, resol
 func (s *tripper) run(ctx context.Context, watcher naming.Watcher) {
 	var localCurrentTargets []*Target
 	for ctx.Err() == nil {
+		fmt.Fprintln(os.Stderr, "Waiting for Next ", s.targetName)
 		updates, err := watcher.Next() // blocking call until new updates are there
 		if err != nil {
+			fmt.Fprintln(os.Stderr, "err ", err)
 			// Watcher next errors are irrecoverable.
 			s.mu.Lock()
 			s.irrecoverableErr = err
 			s.currentTargets = []*Target{}
 			s.mu.Unlock()
 			return
 		}
+		fmt.Fprintln(os.Stderr, "After next ", len(updates))
 
 		for _, u := range updates {
 			if u.Op == naming.Add {

pkg/resolvers/host/host.go

@@ -2,7 +2,10 @@ package hostresolver
 
 import (
 	"fmt"
+	"github.com/prometheus/client_golang/prometheus"
 	"net"
+	"os"
+	"time"
 
 	"github.com/improbable-eng/go-srvlb/grpc"
 	"github.com/improbable-eng/go-srvlb/srv"
@@ -16,6 +19,32 @@ var (
 	ParentHostResolver hostResolverFn = net.LookupHost
 )
 
+var (
+	res = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Namespace: "kedge",
+			Subsystem: "dns_host",
+			Name:      "resolutions",
+			Help:      "debug.",
+		},
+		[]string{"target"},
+	)
+	resHist = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Namespace: "kedge",
+			Subsystem: "dns_host",
+			Name:      "resolutions_hist",
+			Help:      "debug.",
+		},
+		[]string{"target"},
+	)
+)
+
+func init() {
+	prometheus.MustRegister(res)
+	prometheus.MustRegister(resHist)
+}
+
 func NewFromConfig(conf *pb.HostResolver) (target string, namer naming.Resolver, err error) {
 	parent := ParentHostResolver
 	return conf.GetDnsName(), grpcsrvlb.New(newHostResolver(conf.Port, parent)), nil
@@ -35,8 +64,12 @@ func newHostResolver(port uint32, hostResolverFn hostResolverFn) srv.Resolver {
 }
 
 func (r *hostResolver) Lookup(domainName string) ([]*srv.Target, error) {
+	res.WithLabelValues(domainName).Inc()
+	start := time.Now()
 	ips, err := r.hostResolverFn(domainName)
+	resHist.WithLabelValues(domainName).Observe(float64(time.Since(start)))
 	if err != nil {
+		fmt.Fprintln(os.Stderr, "Error", err)
 		return nil, err
 	}