Metrics

Basic metrics and a health status check can be enabled with the --metrics flag (default port 8001, use --metricsPort to specify).

Prometheus

Prometheus metrics are served on /metrics. For each chain that exists, this provides:

<chain>_blocks_processed: the number of blocks processed by the chains listener.
<chain>_latest_processed_block: most recent block that has been processed by the listener.
<chain>_latest_known_block: most recent block that exists on the chain.
<chain>_votes_submitted: number of votes submitted by the relayer.

The endpoint /health will return the current known block height, and a timestamp of when it was first seen for every chain:

{
 "chains": [
   {
     "chainId": "Number",
     "height": "Number",
     "lastUpdated": "Date"
   }
 ]
}

If the timestamp is at least 120 seconds old an error will be returned instead:

{
  "error": "String"
}