feat: add --metrics [flag] to forest (#3609)

CHANGELOG.md

@@ -34,6 +34,9 @@
   files.
 - [#3589](https://github.com/ChainSafe/forest/pull/3589) Add
   `forest-tool archive diff` command for debugging state-root mismatches.
+- [#3609](https://github.com/ChainSafe/forest/pull/3609) Add `--no-metrics`
+  option to `forest` for controlling the availability of the metrics Prometheus
+  server.
 
 ### Changed
 

src/cli_shared/cli/client.rs

@@ -42,6 +42,7 @@ pub struct Client {
     pub data_dir: PathBuf,
     pub genesis_file: Option<String>,
     pub enable_rpc: bool,
+    pub enable_metrics_endpoint: bool,
     pub rpc_token: Option<String>,
     /// If this is true, then we do not validate the imported snapshot.
     /// Otherwise, we validate and compute the states.
@@ -82,6 +83,7 @@ impl Default for Client {
             data_dir: dir.data_dir().to_path_buf(),
             genesis_file: None,
             enable_rpc: true,
+            enable_metrics_endpoint: true,
             rpc_token: None,
             snapshot_path: None,
             snapshot: false,

src/cli_shared/cli/mod.rs

@@ -49,6 +49,9 @@ pub struct CliOpts {
     /// Allow RPC to be active or not (default: true)
     #[arg(short, long)]
     pub rpc: Option<bool>,
+    /// Disable Metrics endpoint
+    #[arg(short, long)]
+    pub no_metrics: bool,
     /// Client JWT token to use for JSON-RPC authentication
     #[arg(short, long)]
     pub token: Option<String>,
@@ -186,9 +189,16 @@ impl CliOpts {
         } else {
             cfg.client.enable_rpc = false;
         }
-        if let Some(metrics_address) = self.metrics_address {
-            cfg.client.metrics_address = metrics_address;
+
+        if self.no_metrics {
+            cfg.client.enable_metrics_endpoint = false;
+        } else {
+            cfg.client.enable_metrics_endpoint = true;
+            if let Some(metrics_address) = self.metrics_address {
+                cfg.client.metrics_address = metrics_address;
+            }
         }
+
         if self.import_snapshot.is_some() && self.import_chain.is_some() {
             anyhow::bail!("Can't set import_snapshot and import_chain at the same time!")
         } else if self.import_snapshot.is_some() && self.consume_snapshot.is_some() {

src/daemon/mod.rs

@@ -193,7 +193,7 @@ pub(super) async fn start(
         });
     }
 
-    {
+    if config.client.enable_metrics_endpoint {
         // Start Prometheus server port
         let prometheus_listener = TcpListener::bind(config.client.metrics_address).context(
             format!("could not bind to {}", config.client.metrics_address),