*: cherry picking blinded metric (#4129)

Cherry-picking #4117 for `v1.7.2`

category: misc
ticket: none

Author: DiogoSantoss

core/fetcher/fetcher.go

@@ -302,6 +302,13 @@ func (f *Fetcher) fetchProposerData(ctx context.Context, slot uint64, defSet cor
 			return nil, errors.Wrap(err, "new proposal")
 		}
 
+		// Track whether the fetched proposal is blinded (built by MEV builder, 1) or local (built by beacon node, 0)
+		var blinded float64
+		if proposal.Blinded {
+			blinded = 1
+		}
+		proposalBlindedGauge.Set(blinded)
+
 		resp[pubkey] = coreProposal
 	}
 

core/fetcher/metrics.go

@@ -0,0 +1,18 @@
+// Copyright © 2022-2025 Obol Labs Inc. Licensed under the terms of a Business Source License 1.1
+
+package fetcher
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+
+	"github.com/obolnetwork/charon/app/promauto"
+)
+
+var (
+	proposalBlindedGauge = promauto.NewGauge(prometheus.GaugeOpts{
+		Namespace: "core",
+		Subsystem: "fetcher",
+		Name:      "proposal_blinded",
+		Help:      "Whether the fetched proposal was blinded (1) or local (0)",
+	})
+)

docs/metrics.md

@@ -57,6 +57,7 @@ when storing metrics from multiple nodes or clusters in one Prometheus instance.
 | `core_consensus_duration_seconds` | Histogram | Duration of the consensus process by protocol, duty, and timer | `protocol, duty, timer` |
 | `core_consensus_error_total` | Counter | Total count of consensus errors by protocol | `protocol` |
 | `core_consensus_timeout_total` | Counter | Total count of consensus timeouts by protocol, duty, and timer | `protocol, duty, timer` |
+| `core_fetcher_proposal_blinded` | Gauge | Whether the fetched proposal was blinded (1) or local (0) |  |
 | `core_parsigdb_exit_total` | Counter | Total number of partially signed voluntary exits per public key | `pubkey` |
 | `core_scheduler_current_epoch` | Gauge | The current epoch |  |
 | `core_scheduler_current_slot` | Gauge | The current slot |  |