Use request.add for header append operation

README.md

@@ -109,7 +109,7 @@ spec:
     # Envoy timeout and retry policy (optional)
     headers:
       request:
-        set:
+        add:
           x-envoy-upstream-rq-timeout-ms: "15000"
           x-envoy-max-retries: "10"
           x-envoy-retry-on: "gateway-error,connect-failure,refused-stream"

artifacts/canaries/canary.yaml

@@ -36,7 +36,7 @@ spec:
     # Envoy timeout and retry policy (optional)
     headers:
       request:
-        set:
+        add:
           x-envoy-upstream-rq-timeout-ms: "15000"
           x-envoy-max-retries: "10"
           x-envoy-retry-on: "gateway-error,connect-failure,refused-stream"

docs/gitbook/how-it-works.md

@@ -128,7 +128,7 @@ metadata:
     # Envoy timeout and retry policy (optional)
     headers:
       request:
-        set:
+        add:
           x-envoy-upstream-rq-timeout-ms: "15000"
           x-envoy-max-retries: "10"
           x-envoy-retry-on: "gateway-error,connect-failure,refused-stream"

pkg/router/istio.go

@@ -85,7 +85,7 @@ func (ir *IstioRouter) Sync(canary *flaggerv1.Canary) error {
 				Rewrite:       canary.Spec.Service.Rewrite,
 				Timeout:       canary.Spec.Service.Timeout,
 				Retries:       canary.Spec.Service.Retries,
-				AppendHeaders: setHeaders(canary),
+				AppendHeaders: addHeaders(canary),
 				Route:         route,
 			},
 		},
@@ -201,7 +201,7 @@ func (ir *IstioRouter) SetRoutes(
 			Rewrite:       canary.Spec.Service.Rewrite,
 			Timeout:       canary.Spec.Service.Timeout,
 			Retries:       canary.Spec.Service.Retries,
-			AppendHeaders: setHeaders(canary),
+			AppendHeaders: addHeaders(canary),
 			Route: []istiov1alpha3.DestinationWeight{
 				{
 					Destination: istiov1alpha3.Destination{
@@ -233,13 +233,13 @@ func (ir *IstioRouter) SetRoutes(
 	return nil
 }
 
-// setHeaders applies headers before forwarding a request to the destination service
+// addHeaders applies headers before forwarding a request to the destination service
 // compatible with Istio 1.0.x and 1.1.0
-func setHeaders(canary *flaggerv1.Canary) (headers map[string]string) {
+func addHeaders(canary *flaggerv1.Canary) (headers map[string]string) {
 	if canary.Spec.Service.Headers != nil &&
 		canary.Spec.Service.Headers.Request != nil &&
-		len(canary.Spec.Service.Headers.Request.Set) > 0 {
-		headers = canary.Spec.Service.Headers.Request.Set
+		len(canary.Spec.Service.Headers.Request.Add) > 0 {
+		headers = canary.Spec.Service.Headers.Request.Add
 	}
 
 	return