app: json_requests feature (#3110)

Add `WithEnforceJSON(true)` parameter when `json_requests` feature is enabled in `featureset`.
This is needed for Nimbus BN to properly handle SubmitProposal requests.

category: feature
ticket: #3108
feature_flag: json_requests

app/eth2wrap/eth2wrap.go

@@ -17,6 +17,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 
 	"github.com/obolnetwork/charon/app/errors"
+	"github.com/obolnetwork/charon/app/featureset"
 	"github.com/obolnetwork/charon/app/forkjoin"
 	"github.com/obolnetwork/charon/app/promauto"
 	"github.com/obolnetwork/charon/app/z"
@@ -74,13 +75,16 @@ func NewMultiHTTP(timeout time.Duration, addresses ...string) (Client, error) {
 	for _, address := range addresses {
 		address := address // Capture range variable.
 
+		parameters := []eth2http.Parameter{
+			eth2http.WithLogLevel(zeroLogInfo),
+			eth2http.WithAddress(address),
+			eth2http.WithTimeout(timeout),
+			eth2http.WithAllowDelayedStart(true),
+			eth2http.WithEnforceJSON(featureset.Enabled(featureset.JSONRequests)),
+		}
+
 		cl := newLazy(func(ctx context.Context) (Client, error) {
-			eth2Svc, err := eth2http.New(ctx,
-				eth2http.WithLogLevel(zeroLogInfo),
-				eth2http.WithAddress(address),
-				eth2http.WithTimeout(timeout),
-				eth2http.WithAllowDelayedStart(true),
-			)
+			eth2Svc, err := eth2http.New(ctx, parameters...)
 			if err != nil {
 				return nil, wrapError(ctx, err, "new eth2 client", z.Str("address", address))
 			}

app/featureset/featureset.go

@@ -37,6 +37,9 @@ const (
 
 	// AggSigDBV2 enables a newer, simpler implementation of `aggsigdb`.
 	AggSigDBV2 Feature = "aggsigdb_v2"
+
+	// JSONRequests enables JSON requests for eth2 client.
+	JSONRequests Feature = "json_requests"
 )
 
 var (
@@ -46,6 +49,7 @@ var (
 		ConsensusParticipate: statusStable,
 		MockAlpha:            statusAlpha,
 		AggSigDBV2:           statusAlpha,
+		JSONRequests:         statusAlpha,
 		// Add all features and there status here.
 	}
 

app/featureset/featureset_internal_test.go

@@ -14,6 +14,7 @@ func TestAllFeatureStatus(t *testing.T) {
 		MockAlpha,
 		EagerDoubleLinear,
 		ConsensusParticipate,
+		JSONRequests,
 	}
 
 	for _, feature := range features {