Configurable monitoring endpoint frequency (#3530)

## Issue Addressed

Closes #3514

## Proposed Changes

- Change default monitoring endpoint frequency to 120 seconds to fit with 30k requests/month limit.
- Allow configuration of the monitoring endpoint frequency using `--monitoring-endpoint-frequency N` where `N` is a value in seconds.

common/monitoring_api/src/lib.rs

@@ -16,7 +16,7 @@ use types::*;
 pub use types::ProcessType;
 
 /// Duration after which we collect and send metrics to remote endpoint.
-pub const UPDATE_DURATION: u64 = 60;
+pub const DEFAULT_UPDATE_DURATION: u64 = 60;
 /// Timeout for HTTP requests.
 pub const TIMEOUT_DURATION: u64 = 5;
 
@@ -55,6 +55,8 @@ pub struct Config {
     /// Path for the cold database required for fetching beacon db size metrics.
     /// Note: not relevant for validator and system metrics.
     pub freezer_db_path: Option<PathBuf>,
+    /// User-defined update period in seconds.
+    pub update_period_secs: Option<u64>,
 }
 
 #[derive(Clone)]
@@ -64,6 +66,7 @@ pub struct MonitoringHttpClient {
     db_path: Option<PathBuf>,
     /// Path to the freezer database.
     freezer_db_path: Option<PathBuf>,
+    update_period: Duration,
     monitoring_endpoint: SensitiveUrl,
     log: slog::Logger,
 }
@@ -74,6 +77,9 @@ impl MonitoringHttpClient {
             client: reqwest::Client::new(),
             db_path: config.db_path.clone(),
             freezer_db_path: config.freezer_db_path.clone(),
+            update_period: Duration::from_secs(
+                config.update_period_secs.unwrap_or(DEFAULT_UPDATE_DURATION),
+            ),
             monitoring_endpoint: SensitiveUrl::parse(&config.monitoring_endpoint)
                 .map_err(|e| format!("Invalid monitoring endpoint: {:?}", e))?,
             log,
@@ -100,10 +106,15 @@ impl MonitoringHttpClient {
         let mut interval = interval_at(
             // Have some initial delay for the metrics to get initialized
             Instant::now() + Duration::from_secs(25),
-            Duration::from_secs(UPDATE_DURATION),
+            self.update_period,
         );
 
-        info!(self.log, "Starting monitoring api"; "endpoint" => %self.monitoring_endpoint);
+        info!(
+            self.log,
+            "Starting monitoring API";
+            "endpoint" => %self.monitoring_endpoint,
+            "update_period" => format!("{}s", self.update_period.as_secs()),
+        );
 
         let update_future = async move {
             loop {