feat(rollup): init telemetry (#50)

Added the ability to start tracing to `stdout` with the following
options:

- tracing target: provided by default with `RUST_LOG` directives. Falls
back to `hera=info` if not provided.
- whether to show the target in stdout: `RUST_LOG_TARGET` (don't show it
only when set to `0`)
- whether to use ANSI formatting and colors: `RUST_LOG_STYLE` (don't use
it only if set to `never`)

Also initialized a Prometheus subscriber on the provided port.
Tested on the Hera binary.

closes #33

bin/hera/Cargo.toml

@@ -11,6 +11,9 @@ keywords.workspace = true
 categories.workspace = true
 
 [dependencies]
+# Local Dependencies
+rollup = { path = "../../crates/rollup" }
+
 # Workspace
 eyre.workspace = true
 tokio = { workspace = true, features = ["rt-multi-thread", "macros"] }

bin/hera/src/main.rs

@@ -7,5 +7,9 @@
 use eyre::Result;
 
 fn main() -> Result<()> {
-    unimplemented!()
+    rollup::init_telemetry_stack(8090)?;
+
+    tracing::info!("Hera OP Stack Rollup node");
+
+    Ok(())
 }

crates/rollup/Cargo.toml

@@ -30,6 +30,10 @@ kona-derive.workspace = true
 kona-primitives.workspace = true
 superchain-registry = { workspace = true, default-features = false }
 
+# Telemetry
+tracing-subscriber = { version = "0.3.18", features = ["env-filter", "fmt"] }   
+metrics-exporter-prometheus = { version = "0.15.3", features = ["http-listener"] }
+
 # Misc
 url = "2.5.2"
 serde_json = "1"

crates/rollup/src/lib.rs

@@ -16,5 +16,8 @@ pub use validator::AttributesValidator;
 mod pipeline;
 pub use pipeline::{new_rollup_pipeline, RollupPipeline};
 
+mod telemetry;
+pub use telemetry::init_telemetry_stack;
+
 /// The identifier of the Hera Execution Extension.
 pub const HERA_EXEX_ID: &str = "hera";

crates/rollup/src/telemetry.rs

@@ -0,0 +1,50 @@
+use std::{io::IsTerminal, net::SocketAddr};
+
+use eyre::{bail, Result};
+use metrics_exporter_prometheus::PrometheusBuilder;
+use tracing::{info, Level};
+use tracing_subscriber::{
+    fmt::Layer as FmtLayer, layer::SubscriberExt, util::SubscriberInitExt, EnvFilter, Layer,
+};
+
+/// Initialize the tracing stack and Prometheus metrics recorder.
+///
+/// This function should be called at the beginning of the program.
+pub fn init_telemetry_stack(metrics_port: u16) -> Result<()> {
+    let filter = EnvFilter::builder().with_default_directive("hera=info".parse()?).from_env_lossy();
+
+    // Whether to use ANSI formatting and colors in the console output.
+    // If unset, always use colors if stdout is a tty.
+    // If set to "never", just disable all colors.
+    let should_use_colors = match std::env::var("RUST_LOG_STYLE") {
+        Ok(val) => val != "never",
+        Err(_) => std::io::stdout().is_terminal(),
+    };
+
+    // Whether to show the tracing target in the console output.
+    // If set, always show the target unless explicitly set to "0".
+    // If unset, show target only if the filter is more verbose than INFO.
+    let should_show_target = match std::env::var("RUST_LOG_TARGET") {
+        Ok(val) => val != "0",
+        Err(_) => filter.max_level_hint().map_or(true, |max_level| max_level > Level::INFO),
+    };
+
+    let std_layer = FmtLayer::new()
+        .with_ansi(should_use_colors)
+        .with_target(should_show_target)
+        .with_writer(std::io::stdout)
+        .with_filter(filter);
+
+    tracing_subscriber::registry().with(std_layer).try_init()?;
+
+    let prometheus_addr = SocketAddr::from(([0, 0, 0, 0], metrics_port));
+    let builder = PrometheusBuilder::new().with_http_listener(prometheus_addr);
+
+    if let Err(e) = builder.install() {
+        bail!("failed to install Prometheus recorder: {:?}", e);
+    } else {
+        info!("Telemetry initialized. Serving Prometheus metrics at: http://{}", prometheus_addr);
+    }
+
+    Ok(())
+}