Updates activator to support h2c (#1260)

cmd/activator/main.go

@@ -25,7 +25,9 @@ import (
 	"github.com/knative/serving/pkg/activator"
 	clientset "github.com/knative/serving/pkg/client/clientset/versioned"
 	"github.com/knative/serving/pkg/controller"
+	h2cutil "github.com/knative/serving/pkg/h2c"
 	"github.com/knative/serving/pkg/signals"
+	"github.com/knative/serving/third_party/h2c"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 )
@@ -45,7 +47,13 @@ type activationHandler struct {
 type retryRoundTripper struct{}
 
 func (rrt retryRoundTripper) RoundTrip(r *http.Request) (*http.Response, error) {
-	transport := http.DefaultTransport
+	var transport http.RoundTripper
+
+	transport = http.DefaultTransport
+	if r.ProtoMajor == 2 {
+		transport = h2cutil.NewTransport()
+	}
+
 	resp, err := transport.RoundTrip(r)
 	// TODO: Activator should retry with backoff.
 	// https://github.com/knative/serving/issues/1229
@@ -79,9 +87,11 @@ func (a *activationHandler) handler(w http.ResponseWriter, r *http.Request) {
 	}
 	proxy := httputil.NewSingleHostReverseProxy(target)
 	proxy.Transport = retryRoundTripper{}
+
 	// TODO: Clear the host to avoid 404's.
 	// https://github.com/elafros/elafros/issues/964
 	r.Host = ""
+
 	proxy.ServeHTTP(w, r)
 }
 
@@ -114,5 +124,5 @@ func main() {
 	}()
 
 	http.HandleFunc("/", ah.handler)
-	http.ListenAndServe(":8080", nil)
-}
+	h2c.ListenAndServe(":8080", nil)
+}

pkg/h2c/transport.go

@@ -0,0 +1,21 @@
+package h2c
+
+import (
+	"crypto/tls"
+	"net"
+	"net/http"
+
+	"golang.org/x/net/http2"
+)
+
+// NewTransport will reroute all https traffic to http. This is
+// to explicitly allow h2c (http2 without TLS) transport.
+// See https://github.com/golang/go/issues/14141 for more details.
+func NewTransport() http.RoundTripper {
+	return &http2.Transport{
+		AllowHTTP: true,
+		DialTLS: func(netw, addr string, cfg *tls.Config) (net.Conn, error) {
+			return net.Dial(netw, addr)
+		},
+	}
+}