feat: add cluster_name and cluster_peer labels to Prometheus metrics (#277)

Move cluster_name and cluster_peer from mev-boost relabel_configs to
global external_labels so all metrics (charon, mev-boost) include
these identity labels. Also add the missing sed substitutions in
run.sh that were preventing the variables from being rendered.

Author: apham0001

prometheus/prometheus.yml.example

@@ -3,6 +3,8 @@ global:
   evaluation_interval: 30s # Evaluate rules every 30 seconds.
   external_labels:
     service_owner: $SERVICE_OWNER # replace this with your Operator name you want to be identified by, it helps us route alerts and metrics to your notification channels easily
+    cluster_name: $CLUSTER_NAME
+    cluster_peer: $CLUSTER_PEER
 
 remote_write:
   - url: https://vm.monitoring.gcp.obol.tech/write
@@ -32,11 +34,6 @@ scrape_configs:
   - job_name: "mev-boost"
     static_configs:
       - targets: ["mev-mevboost:18551","mev-boost:18551"]
-    relabel_configs:
-      - target_label: cluster_name
-        replacement: "$CLUSTER_NAME"
-      - target_label: cluster_peer
-        replacement: "$CLUSTER_PEER"
   - job_name: "lodestar"
     static_configs:
       - targets: [ "lodestar:5064" ]

prometheus/run.sh

@@ -17,6 +17,8 @@ fi
 
 sed -e "s|\$PROM_REMOTE_WRITE_TOKEN|${PROM_REMOTE_WRITE_TOKEN}|g" \
     -e "s|\$SERVICE_OWNER|${SERVICE_OWNER}|g" \
+    -e "s|\$CLUSTER_NAME|${CLUSTER_NAME}|g" \
+    -e "s|\$CLUSTER_PEER|${CLUSTER_PEER}|g" \
     -e "s|\$ALERT_DISCORD_IDS|${ALERT_DISCORD_IDS}|g" \
     /etc/prometheus/prometheus.yml.example > /etc/prometheus/prometheus.yml