Add additional metrics for BeaconChain

beacon_node/http_server/src/metrics/local_metrics.rs

@@ -0,0 +1,66 @@
+use beacon_chain::{BeaconChain, BeaconChainTypes};
+use prometheus::{IntGauge, Opts, Registry};
+use slot_clock::SlotClock;
+use types::Slot;
+
+pub struct LocalMetrics {
+    present_slot: IntGauge,
+    best_slot: IntGauge,
+    validator_count: IntGauge,
+    justified_epoch: IntGauge,
+    finalized_epoch: IntGauge,
+}
+
+impl LocalMetrics {
+    /// Create a new instance.
+    pub fn new() -> Result<Self, prometheus::Error> {
+        Ok(Self {
+            present_slot: {
+                let opts = Opts::new("present_slot", "slot_at_time_of_scrape");
+                IntGauge::with_opts(opts)?
+            },
+            best_slot: {
+                let opts = Opts::new("best_slot", "slot_of_block_at_chain_head");
+                IntGauge::with_opts(opts)?
+            },
+            validator_count: {
+                let opts = Opts::new("validator_count", "number_of_validators");
+                IntGauge::with_opts(opts)?
+            },
+            justified_epoch: {
+                let opts = Opts::new("justified_epoch", "state_justified_epoch");
+                IntGauge::with_opts(opts)?
+            },
+            finalized_epoch: {
+                let opts = Opts::new("finalized_epoch", "state_finalized_epoch");
+                IntGauge::with_opts(opts)?
+            },
+        })
+    }
+
+    /// Registry this instance with the `registry`.
+    pub fn register(&self, registry: &Registry) -> Result<(), prometheus::Error> {
+        registry.register(Box::new(self.present_slot.clone()))?;
+        registry.register(Box::new(self.best_slot.clone()))?;
+        registry.register(Box::new(self.validator_count.clone()))?;
+
+        Ok(())
+    }
+
+    /// Update the metrics in `self` to the latest values.
+    pub fn update<T: BeaconChainTypes>(&self, beacon_chain: &BeaconChain<T>) {
+        let state = &beacon_chain.head().beacon_state;
+
+        let present_slot = beacon_chain
+            .slot_clock
+            .present_slot()
+            .unwrap_or_else(|_| None)
+            .unwrap_or_else(|| Slot::new(0));
+        self.present_slot.set(present_slot.as_u64() as i64);
+
+        self.best_slot.set(state.slot.as_u64() as i64);
+        self.validator_count.set(state.validator_registry.len() as i64);
+        self.justified_epoch.set(state.current_justified_epoch.as_u64() as i64);
+        self.finalized_epoch.set(state.finalized_epoch.as_u64() as i64);
+    }
+}