adding in debug flag

changelog/james-prysm_json-only-validator.md

@@ -0,0 +1,3 @@
+### Added
+
+- Added `json-only` debugging feature flag on validator client that forces use of json requests on api endpoints that support both json and ssz.

config/features/config.go

@@ -53,6 +53,7 @@ type Flags struct {
 	EnableDutiesV2                      bool // EnableDutiesV2 sets validator client to use the get Duties V2 endpoint
 	EnableWeb                           bool // EnableWeb enables the webui on the validator client
 	SSZOnly                             bool // SSZOnly forces the validator client to use SSZ for communication with the beacon node when REST mode is enabled (useful for debugging)
+	JSONOnly                            bool // JSONOnly forces the validator client to use JSON for communication with the beacon node when REST mode is enabled (useful for debugging)
 	// Logging related toggles.
 	DisableGRPCConnectionLogs bool // Disables logging when a new grpc client has connected.
 	EnableFullSSZDataLogging  bool // Enables logging for full ssz data on rejected gossip messages
@@ -349,6 +350,10 @@ func ConfigureValidator(ctx *cli.Context) error {
 		logEnabled(SSZOnly)
 		cfg.SSZOnly = true
 	}
+	if ctx.Bool(JSONOnly.Name) {
+		logEnabled(JSONOnly)
+		cfg.JSONOnly = true
+	}
 
 	cfg.KeystoreImportDebounceInterval = ctx.Duration(dynamicKeyReloadDebounceInterval.Name)
 	Init(cfg)

config/features/flags.go

@@ -207,6 +207,12 @@ var (
 		Name:  "ssz-only",
 		Usage: "(debug): Forces the validator client to use SSZ for communication with the beacon node when REST mode is enabled",
 	}
+
+	// JSONOnly forces the validator client to use JSON for communication with the beacon node when REST mode is enabled
+	JSONOnly = &cli.BoolFlag{
+		Name:  "json-only",
+		Usage: "(debug): Forces the validator client to use JSON for communication with the beacon node when REST mode is enabled",
+	}
 )
 
 // devModeFlags holds list of flags that are set when development mode is on.

validator/client/beacon-api/rest_handler_client.go

@@ -82,6 +82,9 @@ func (c *BeaconApiRestHandler) GetSSZ(ctx context.Context, endpoint string) ([]b
 	if features.Get().SSZOnly {
 		acceptHeaderString = api.OctetStreamMediaType
 	}
+	if features.Get().JSONOnly {
+		acceptHeaderString = api.JsonMediaType
+	}
 	req.Header.Set("Accept", acceptHeaderString)
 	httpResp, err := c.client.Do(req)
 	if err != nil {
@@ -115,7 +118,7 @@ func (c *BeaconApiRestHandler) GetSSZ(ctx context.Context, endpoint string) ([]b
 		return nil, nil, errorJson
 	}
 
-	if features.Get().SSZOnly && contentType != api.OctetStreamMediaType {
+	if (features.Get().SSZOnly && contentType != api.OctetStreamMediaType) || (features.Get().JSONOnly && contentType != api.JsonMediaType) {
 		return nil, nil, errors.Errorf("server responded with non primary accept type %s", contentType)
 	}