adding routing delegate in dynamic channel support for routing throug…

…h sidecar (#658)

codegen/templates/tchannel_client.tmpl

@@ -162,9 +162,13 @@ func initializeDynamicChannel(deps *module.Dependencies, headerPatterns []string
 
 		ruleWrapper := ruleengine.RuleWrapper{}
 		for _, routingConfig := range alternateServiceDetail.RoutingConfigs {
+			ruleValue := []string{routingConfig.ServiceName}
+			rd := routingConfig.RoutingDelegate
+			if rd != nil {
+				ruleValue = append(ruleValue, *rd)
+			}
 			rawRule := ruleengine.RawRule{Patterns: []string{textproto.CanonicalMIMEHeaderKey(routingConfig.HeaderName),
-			 strings.ToLower(routingConfig.HeaderValue)},
-				Value: routingConfig.ServiceName}
+				strings.ToLower(routingConfig.HeaderValue)}, Value: ruleValue}
 			headerPatterns = append(headerPatterns, textproto.CanonicalMIMEHeaderKey(routingConfig.HeaderName))
 			ruleWrapper.Rules = append(ruleWrapper.Rules, rawRule)
 

config/config.go

@@ -33,9 +33,10 @@ type EnvConfig map[string]struct {
 }
 
 type RoutingConfig struct {
-	HeaderName  string `yaml:"headerName" json:"headerName"`
-	HeaderValue string `yaml:"headerValue" json:"headerValue"`
-	ServiceName string `yaml:"serviceName" json:"serviceName"`
+	HeaderName      string  `yaml:"headerName" json:"headerName"`
+	HeaderValue     string  `yaml:"headerValue" json:"headerValue"`
+	ServiceName     string  `yaml:"serviceName" json:"serviceName"`
+	RoutingDelegate *string `yaml:"rd,omitempty" json:"rd,omitempty"`
 }
 
 type ServiceRouting struct {

examples/example-gateway/config/production.yaml

@@ -72,6 +72,7 @@ clients.baz.alternates:
     - headerName: x-container
       headerValue: ^sandbox$
       serviceName: basicSandbox
+      rd: reverse-proxy
     - headerName: x-test-env
       headerValue: ^sandbox$
       serviceName: nomatch

runtime/tchannel_client.go

@@ -224,7 +224,7 @@ func (c *TChannelClient) call(
 	err = c.ch.RunWithRetry(ctx, func(ctx netContext.Context, rs *tchannel.RequestState) (cerr error) {
 		call.resHeaders, call.success = nil, false
 
-		sc := c.getDynamicChannelWithFallback(reqHeaders, c.sc)
+		sc, ctx := c.getDynamicChannelWithFallback(reqHeaders, c.sc, ctx)
 		call.call, cerr = sc.BeginCall(ctx, call.serviceMethod, &tchannel.CallOptions{
 			Format:          tchannel.Thrift,
 			ShardKey:        GetShardKeyFromCtx(ctx),
@@ -275,10 +275,10 @@ func (c *TChannelClient) call(
 
 // first rule match, would be the choosen channel. if nothing matches fallback to default channel
 func (c *TChannelClient) getDynamicChannelWithFallback(reqHeaders map[string]string,
-	sc *tchannel.SubChannel) *tchannel.SubChannel {
+	sc *tchannel.SubChannel, ctx netContext.Context) (*tchannel.SubChannel, netContext.Context) {
 	ch := sc
 	if c.ruleEngine == nil {
-		return ch
+		return ch, ctx
 	}
 	for _, headerPattern := range c.headerPatterns {
 		// this header is not present, so can't match a rule
@@ -291,11 +291,14 @@ func (c *TChannelClient) getDynamicChannelWithFallback(reqHeaders map[string]str
 		if !match {
 			continue
 		}
-		serviceName := val.(string)
+		serviceDetails := val.([]string)
 		// we know service has a channel, as this was constructed in c'tor
-		ch = c.altChannelMap[serviceName]
-		return ch
+		ch = c.altChannelMap[serviceDetails[0]]
+		if len(serviceDetails) > 1 {
+			ctx = WithRoutingDelegate(ctx, serviceDetails[1])
+		}
+		return ch, ctx
 	}
 	// if nothing matches return the default channel/**/
-	return ch
+	return ch, ctx
 }