Add ALERT_DISCORD_IDS label and env variable (#387)

Discord template:
```
{{ with index .Labels "alert_discord_ids" }}
    {{ $formatted := reReplaceAll "," "> <@" . }}
    <@{{ $formatted }}>
{{ end }}
```

Author: DiogoSantoss

.env.sample.hoodi

@@ -196,6 +196,12 @@ MEV_RELAYS=https://0x98f0ef62f00780cf8eb06701a7d22725b9437d4768bb19b363e882ae871
 # Prometheus service owner used to uniquely identify user from which metrics are pushed.
 #SERVICE_OWNER=charon_user
 
+# To get Alerted with Obol Agent monitoring on Discord, specify your Discord ID(s) below.
+# Enable developer mode on discord with User Settings > Advanced. 
+# Then right click on a user's profile picture or name and select Copy ID to get a unique 18-digit number that represents their account. 
+# Specify multiple discord IDs using comma separation. (e.g. `DISCORD_IDS=123456789098765432,098765432123456789`)
+#ALERT_DISCORD_IDS=""
+
 # Uncomment these if you have log exporting with Alloy
 # and want to disable log export on a particular container.
 #EL_NETHERMIND_ALLOY_MONITORED=false

.env.sample.mainnet

@@ -196,6 +196,12 @@ MEV_RELAYS=https://0xa15b52576bcbf1072f4a011c0f99f9fb6c66f3e1ff321f11f461d15e31b
 # Prometheus service owner used to uniquely identify user from which metrics are pushed.
 #SERVICE_OWNER=charon_user
 
+# To get Alerted with Obol Agent monitoring on Discord, specify your Discord ID(s) below.
+# Enable developer mode on discord with User Settings > Advanced. 
+# Then right click on a user's profile picture or name and select Copy ID to get a unique 18-digit number that represents their account. 
+# Specify multiple discord IDs using comma separation. (e.g. `DISCORD_IDS=123456789098765432,098765432123456789`)
+#ALERT_DISCORD_IDS=""
+
 # Uncomment these if you have log exporting with Alloy
 # and want to disable log export on a particular container.
 #EL_NETHERMIND_ALLOY_MONITORED=false

prometheus/prometheus.yml.example

@@ -23,9 +23,13 @@ scrape_configs:
   - job_name: "charon"
     static_configs:
       - targets: ["charon:3620"]
+    relabel_configs:
+      - target_label: alert_discord_ids
+        replacement: "$ALERT_DISCORD_IDS"
   - job_name: "mev-boost"
     static_configs:
       - targets: ["mev-mevboost:18551"]
+
   - job_name: "lodestar"
     static_configs:
       - targets: ["lodestar:5064"]

prometheus/run.sh

@@ -14,6 +14,7 @@ fi
 
 sed -e "s|\$PROM_REMOTE_WRITE_TOKEN|${PROM_REMOTE_WRITE_TOKEN}|g" \
     -e "s|\$SERVICE_OWNER|${SERVICE_OWNER}|g" \
+    -e "s|\$ALERT_DISCORD_IDS|${ALERT_DISCORD_IDS}|g" \
     /etc/prometheus/prometheus.yml.example > /etc/prometheus/prometheus.yml
 
 /bin/prometheus \