Add Http2Origin option to force HTTP/2 origin connections

If `http2Origin` is set, it will set `ForceAttemptHTTP2` in the transport config of the `OriginService`.

cmd/cloudflared/tunnel/cmd.go

@@ -821,6 +821,13 @@ func configureProxyFlags(shouldHide bool) []cli.Flag {
 			EnvVars: []string{"TUNNEL_NO_CHUNKED_ENCODING"},
 			Hidden:  shouldHide,
 		}),
+		altsrc.NewBoolFlag(&cli.BoolFlag{
+			Name:    ingress.Http2OriginFlag,
+			Usage:   "Enables HTTP/2 origin servers.",
+			EnvVars: []string{"TUNNEL_ORIGIN_ENABLE_HTTP2"},
+			Hidden:  shouldHide,
+			Value:   false,
+		}),
 	}
 	return append(flags, sshFlags(shouldHide)...)
 }

config/configuration.go

@@ -227,6 +227,8 @@ type OriginRequestConfig struct {
 	ProxyType *string `yaml:"proxyType" json:"proxyType,omitempty"`
 	// IP rules for the proxy service
 	IPRules []IngressIPRule `yaml:"ipRules" json:"ipRules,omitempty"`
+	// Attempt to connect to origin with HTTP/2
+	Http2Origin *bool `yaml:"http2Origin" json:"http2Origin,omitempty"`
 }
 
 type IngressIPRule struct {

config/configuration_test.go

@@ -139,7 +139,8 @@ var rawConfig = []byte(`
 			"ports": [443, 4443],
 			"allow": true
 		}
-	]
+	],
+	"http2Origin": true
 }
 `)
 
@@ -188,6 +189,7 @@ func assertConfig(
 	assert.Equal(t, true, *config.NoTLSVerify)
 	assert.Equal(t, uint(9000), *config.ProxyPort)
 	assert.Equal(t, "socks", *config.ProxyType)
+	assert.Equal(t, true, *config.Http2Origin)
 
 	privateV4 := "10.0.0.0/8"
 	privateV6 := "fc00::/7"

ingress/config.go

@@ -35,6 +35,7 @@ const (
 	NoChunkedEncodingFlag         = "no-chunked-encoding"
 	ProxyAddressFlag              = "proxy-address"
 	ProxyPortFlag                 = "proxy-port"
+	Http2OriginFlag               = "http2-origin"
 )
 
 const (
@@ -93,6 +94,7 @@ func originRequestFromSingeRule(c *cli.Context) OriginRequestConfig {
 	var proxyAddress = defaultProxyAddress
 	var proxyPort uint
 	var proxyType string
+	var http2Origin bool
 	if flag := ProxyConnectTimeoutFlag; c.IsSet(flag) {
 		connectTimeout = config.CustomDuration{Duration: c.Duration(flag)}
 	}
@@ -136,9 +138,13 @@ func originRequestFromSingeRule(c *cli.Context) OriginRequestConfig {
 		// Note TUN-3758 , we use Int because UInt is not supported with altsrc
 		proxyPort = uint(c.Int(flag))
 	}
+	if flag := Http2OriginFlag; c.IsSet(flag) {
+		http2Origin = c.Bool(flag)
+	}
 	if c.IsSet(Socks5Flag) {
 		proxyType = socksProxy
 	}
+
 	return OriginRequestConfig{
 		ConnectTimeout:         connectTimeout,
 		TLSTimeout:             tlsTimeout,
@@ -155,6 +161,7 @@ func originRequestFromSingeRule(c *cli.Context) OriginRequestConfig {
 		ProxyAddress:           proxyAddress,
 		ProxyPort:              proxyPort,
 		ProxyType:              proxyType,
+		Http2Origin:            http2Origin,
 	}
 }
 
@@ -263,6 +270,8 @@ type OriginRequestConfig struct {
 	ProxyType string `yaml:"proxyType" json:"proxyType"`
 	// IP rules for the proxy service
 	IPRules []ipaccess.Rule `yaml:"ipRules" json:"ipRules"`
+	// Attempt to connect to origin with HTTP/2
+	Http2Origin bool `yaml:"http2Origin" json:"http2Origin"`
 }
 
 func (defaults *OriginRequestConfig) setConnectTimeout(overrides config.OriginRequestConfig) {

ingress/origin_service.go

@@ -291,6 +291,7 @@ func newHTTPTransport(service OriginService, cfg OriginRequestConfig, log *zerol
 		TLSHandshakeTimeout:   cfg.TLSTimeout.Duration,
 		ExpectContinueTimeout: 1 * time.Second,
 		TLSClientConfig:       &tls.Config{RootCAs: originCertPool, InsecureSkipVerify: cfg.NoTLSVerify},
+		ForceAttemptHTTP2:     cfg.Http2Origin,
 	}
 	if _, isHelloWorld := service.(*helloWorld); !isHelloWorld && cfg.OriginServerName != "" {
 		httpTransport.TLSClientConfig.ServerName = cfg.OriginServerName