Document client monitoring usage

docs/usage/client-monitoring.md

@@ -0,0 +1,49 @@
+# Client monitoring
+
+Lodestar has the ability to send client stats to a remote service for collection.
+At the moment, the main service offering remote monitoring is [beaconcha.in](https://beaconcha.in/).
+
+Instructions for setting up client monitoring with *beaconcha.in* can be found in their docs about
+[Mobile App <> Node Monitoring](https://kb.beaconcha.in/beaconcha.in-explorer/mobile-app-less-than-greater-than-beacon-node)
+and in your [account settings](https://beaconcha.in/user/settings#app).
+
+## Configuration
+
+Lodestar provides CLI options to configure monitoring on both the beacon node and validator client.
+
+### Remote endpoint URL
+
+Client monitoring can be enabled by setting the `--monitoring.endpoint` flag to a remote service endpoint URL.
+As monitoring relies on metrics data, it is required that metrics are also enabled by supplying the `--metrics` flag.
+
+```bash
+lodestar beacon --monitoring.endpoint "https://beaconcha.in/api/v1/client/metrics?apikey={apikey}&machine={machineName}" --metrics
+```
+
+In case of *beaconcha.in*, the API key can be found in your [account settings](https://beaconcha.in/user/settings#api).
+Setting the machine is optional but it is especially useful if you are monitoring multiple nodes.
+
+<!-- prettier-ignore-start -->
+!!! note
+    When sending data to a remote service you should be conscious about security:
+
+    - Only use a service that you trust as this will send information which may identify you
+      and associate your validators, IP address and other personal information.
+    - Always use a HTTPS connection (i.e. a URL starting with `https://`) to prevent the traffic
+      from being intercepted in transit and leaking information.
+<!-- prettier-ignore-end -->
+
+More details about the data sent to the remote service can be found in the [specification](https://docs.google.com/document/d/1qPWAVRjPCENlyAjUBwGkHMvz9qLdd_6u9DPZcNxDBpc).
+
+It is also possible to print out the data sent to the remote service by enabling debug logs which can be done by supplying the `--logLevel debug` flag.
+
+### Monitoring interval
+
+It is possible to adjust the interval between sending client stats to the remote service by
+setting the `--monitoring.interval` flag. It takes an integer value in milliseconds, the default is `60000` which means data is sent once a minute.
+
+```bash
+lodestar beacon --monitoring.interval 60000
+```
+
+Increasing the monitoring interval can be useful if you are running into rate limit errors when posting large amounts of data for multiple nodes.

mkdocs.yml

@@ -76,6 +76,7 @@ nav:
       - Validator management: usage/validator-management.md
       - Prometheus & Grafana Setup: usage/prometheus-grafana.md
       - MEV Builder Integration: usage/mev-integration.md 
+      - Client monitoring: usage/client-monitoring.md
   - Reference:
       - Command line: reference/cli.md
   - Libraries: libraries/index.md

packages/cli/src/cmds/validator/options.ts

@@ -305,7 +305,6 @@ export const validatorOptions: ICliCommandOptions<IValidatorCliArgs> = {
     description: "Interval in milliseconds between sending client stats to the remote service",
     defaultDescription: String(validatorMonitoringDefaultOptions.interval),
     group: "monitoring",
-    hidden: true,
   },
 
   "monitoring.initialDelay": {

packages/cli/src/options/beaconNodeOptions/monitoring.ts

@@ -32,7 +32,6 @@ export const options: ICliCommandOptions<IMonitoringArgs> = {
     description: "Interval in milliseconds between sending client stats to the remote service",
     defaultDescription: String(defaultOptions.monitoring.interval),
     group: "monitoring",
-    hidden: true,
   },
 
   "monitoring.initialDelay": {