feat(proxyd): ability to add additional headers to backend requests (#8134)

proxyd/proxyd/backend.go

@@ -139,6 +139,7 @@ type Backend struct {
 	wsURL                string
 	authUsername         string
 	authPassword         string
+	headers              map[string]string
 	client               *LimitedHTTPClient
 	dialer               *websocket.Dialer
 	maxRetries           int
@@ -170,6 +171,12 @@ func WithBasicAuth(username, password string) BackendOpt {
 	}
 }
 
+func WithHeaders(headers map[string]string) BackendOpt {
+	return func(b *Backend) {
+		b.headers = headers
+	}
+}
+
 func WithTimeout(timeout time.Duration) BackendOpt {
 	return func(b *Backend) {
 		b.client.Timeout = timeout
@@ -535,6 +542,10 @@ func (b *Backend) doForward(ctx context.Context, rpcReqs []*RPCReq, isBatch bool
 	httpReq.Header.Set("content-type", "application/json")
 	httpReq.Header.Set("X-Forwarded-For", xForwardedFor)
 
+	for name, value := range b.headers {
+		httpReq.Header.Set(name, value)
+	}
+
 	start := time.Now()
 	httpRes, err := b.client.DoLimited(httpReq)
 	if err != nil {

proxyd/proxyd/config.go

@@ -94,6 +94,7 @@ type BackendConfig struct {
 	ClientCertFile   string            `toml:"client_cert_file"`
 	ClientKeyFile    string            `toml:"client_key_file"`
 	StripTrailingXFF bool              `toml:"strip_trailing_xff"`
+	Headers          map[string]string `toml:"headers"`
 
 	ConsensusSkipPeerCountCheck bool   `toml:"consensus_skip_peer_count"`
 	ConsensusForcedCandidate    bool   `toml:"consensus_forced_candidate"`

proxyd/proxyd/proxyd.go

@@ -130,6 +130,18 @@ func Start(config *Config) (*Server, func(), error) {
 			}
 			opts = append(opts, WithBasicAuth(cfg.Username, passwordVal))
 		}
+
+		headers := map[string]string{}
+		for headerName, headerValue := range cfg.Headers {
+			headerValue, err := ReadFromEnvOrConfig(headerValue)
+			if err != nil {
+				return nil, nil, err
+			}
+
+			headers[headerName] = headerValue
+		}
+		opts = append(opts, WithHeaders(headers))
+
 		tlsConfig, err := configureBackendTLS(cfg)
 		if err != nil {
 			return nil, nil, err