http resolver

validator/client/BUILD.bazel

@@ -10,6 +10,7 @@ go_library(
         "log.go",
         "metrics.go",
         "multiple_endpoints_grpc_resolver.go",
+        "multiple_endpoints_http_resolver.go",
         "propose.go",
         "propose_protect.go",
         "registration.go",

validator/client/multiple_endpoints_http_resolver.go

@@ -0,0 +1,70 @@
+package client
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/prysmaticlabs/prysm/v4/network/httputil"
+)
+
+// MultipleEndpointsHTTPResolver is a custom resolver for HTTP clients that supports multiple addresses.
+type MultipleEndpointsHTTPResolver struct {
+	addresses  []string
+	currentIdx int
+	client     *http.Client
+}
+
+// NewMultipleEndpointsHTTPResolver creates a new instance of MultipleEndpointsHTTPResolver.
+func NewMultipleEndpointsHTTPResolver(addresses []string) *MultipleEndpointsHTTPResolver {
+	return &MultipleEndpointsHTTPResolver{
+		addresses:  addresses,
+		currentIdx: 0,
+		client:     &http.Client{},
+	}
+}
+
+func (r *MultipleEndpointsHTTPResolver) HttpMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		// Attempt to send the request to the current endpoint
+		err := r.sendRequest(req, w)
+
+		// Switch to the next endpoint and retry if there is an error
+		for i := 0; i < len(r.addresses)-1 && err != nil; i++ {
+			r.switchEndpoint()
+			err = r.sendRequest(req, w)
+		}
+
+		if err != nil {
+			httputil.HandleError(w, fmt.Sprintf("failed to send request: %v", err), http.StatusInternalServerError)
+			return
+		}
+
+		next.ServeHTTP(w, req)
+	})
+}
+
+// sendRequest sends the HTTP request to the current endpoint.
+func (r *MultipleEndpointsHTTPResolver) sendRequest(req *http.Request, w http.ResponseWriter) error {
+	// Update the request URL with the current endpoint
+	req.URL.Host = r.resolveEndpoint()
+
+	// Send the HTTP request using the client
+	resp, err := r.client.Do(req)
+	if err != nil {
+		// Optionally handle specific errors or log them
+		httputil.HandleError(w, fmt.Sprintf("error sending request to %s: %v\n", r.resolveEndpoint(), err), http.StatusInternalServerError)
+		return err
+	}
+	defer resp.Body.Close()
+	return nil
+}
+
+// resolveEndpoint returns the current endpoint based on the resolver's state.
+func (r *MultipleEndpointsHTTPResolver) resolveEndpoint() string {
+	return r.addresses[r.currentIdx]
+}
+
+// switchToNextEndpoint switches to the next available endpoint, this is circular.
+func (r *MultipleEndpointsHTTPResolver) switchEndpoint() {
+	r.currentIdx = (r.currentIdx + 1) % len(r.addresses)
+}