fix(harness): add harness debug feature (#1012)

crates/harness/build.sh

@@ -3,7 +3,19 @@
 # Ensure the script runs in the folder that contains this script
 cd "$(dirname "$0")"
 
-cargo build --release --package tlsn-harness-runner --package tlsn-harness-executor --package tlsn-server-fixture --package tlsn-harness-plot
+RUNNER_FEATURES=""
+EXECUTOR_FEATURES=""
+
+if [ "$1" = "debug" ]; then
+    RUNNER_FEATURES="--features debug"
+    EXECUTOR_FEATURES="--no-default-features --features debug"
+fi
+
+cargo build --release \
+    --package tlsn-harness-runner $RUNNER_FEATURES \
+    --package tlsn-harness-executor $EXECUTOR_FEATURES \
+    --package tlsn-server-fixture \
+    --package tlsn-harness-plot
 
 mkdir -p bin
 

crates/harness/executor/Cargo.toml

@@ -4,6 +4,12 @@ version = "0.1.0"
 edition = "2024"
 publish = false
 
+[features]
+# Disable tracing events as a workaround for issue 959. 
+default = ["tracing/release_max_level_off"]
+# Used to debug the executor itself.
+debug = []
+
 [lib]
 name = "harness_executor"
 crate-type = ["cdylib", "rlib"]
@@ -28,8 +34,7 @@ tokio = { workspace = true, features = ["full"] }
 tokio-util = { workspace = true, features = ["compat"] }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
-# Disable tracing events as a workaround for issue 959. 
-tracing = { workspace = true, features = ["release_max_level_off"] }
+tracing = { workspace = true }
 wasm-bindgen = { workspace = true }
 tlsn-wasm = { workspace = true }
 js-sys = { workspace = true }

crates/harness/runner/Cargo.toml

@@ -7,6 +7,10 @@ publish = false
 [lib]
 name = "harness_runner"
 
+[features]
+# Used to debug the runner itself.
+debug = []
+
 [dependencies]
 tlsn-harness-core = { workspace = true }
 tlsn-server-fixture = { workspace = true }

crates/harness/runner/src/debug_prelude.rs

@@ -0,0 +1,17 @@
+#![allow(unused_imports)]
+pub use futures::FutureExt;
+
+pub use tracing::{debug, error};
+
+pub use chromiumoxide::{
+    Browser, Page,
+    cdp::{
+        browser_protocol::{
+            log::{EventEntryAdded, LogEntryLevel},
+            network::{EnableParams, SetCacheDisabledParams},
+            page::ReloadParams,
+        },
+        js_protocol::runtime::EventExceptionThrown,
+    },
+    handler::HandlerConfig,
+};

crates/harness/runner/src/executor.rs

@@ -21,6 +21,9 @@ use harness_core::{
 
 use crate::{Target, network::Namespace, rpc::Rpc};
 
+#[cfg(feature = "debug")]
+use crate::debug_prelude::*;
+
 pub struct Executor {
     ns: Namespace,
     config: ExecutorConfig,
@@ -66,20 +69,34 @@ impl Executor {
                     Id::One => self.config.network().rpc_1,
                 };
 
-                let process = duct::cmd!(
-                    "sudo",
-                    "ip",
-                    "netns",
-                    "exec",
-                    self.ns.name(),
-                    "env",
+                let mut args = vec![
+                    "ip".into(),
+                    "netns".into(),
+                    "exec".into(),
+                    self.ns.name().into(),
+                    "env".into(),
                     format!("CONFIG={}", serde_json::to_string(&self.config)?),
-                    executor_path
-                )
-                .stdout_capture()
-                .stderr_capture()
-                .unchecked()
-                .start()?;
+                ];
+
+                if cfg!(feature = "debug") {
+                    let level = &std::env::var("RUST_LOG").unwrap_or("debug".to_string());
+                    args.push("env".into());
+                    args.push(format!("RUST_LOG={}", level));
+                };
+
+                args.push(executor_path.to_str().expect("valid path").into());
+
+                let process = duct::cmd("sudo", args);
+
+                let process = if !cfg!(feature = "debug") {
+                    process
+                        .stdout_capture()
+                        .stderr_capture()
+                        .unchecked()
+                        .start()?
+                } else {
+                    process.unchecked().start()?
+                };
 
                 let rpc = Rpc::new_native(rpc_addr).await?;
 
@@ -119,10 +136,13 @@ impl Executor {
                     "--no-sandbox",
                     format!("--user-data-dir={tmp}"),
                     format!("--allowed-ips=10.250.0.1"),
-                )
-                .stderr_capture()
-                .stdout_capture()
-                .start()?;
+                );
+
+                let process = if !cfg!(feature = "debug") {
+                    process.stderr_capture().stdout_capture().start()?
+                } else {
+                    process.start()?
+                };
 
                 const TIMEOUT: usize = 10000;
                 const DELAY: usize = 100;
@@ -171,6 +191,38 @@ impl Executor {
                     .new_page(&format!("http://{wasm_addr}:{wasm_port}/index.html"))
                     .await?;
 
+                #[cfg(feature = "debug")]
+                tokio::spawn(register_listeners(page.clone()).await?);
+
+                #[cfg(feature = "debug")]
+                async fn register_listeners(page: Page) -> Result<impl Future<Output = ()>> {
+                    let mut logs = page.event_listener::<EventEntryAdded>().await?.fuse();
+                    let mut exceptions =
+                        page.event_listener::<EventExceptionThrown>().await?.fuse();
+
+                    Ok(futures::future::join(
+                        async move {
+                            while let Some(event) = logs.next().await {
+                                let entry = &event.entry;
+                                match entry.level {
+                                    LogEntryLevel::Error => {
+                                        error!("{:?}", entry);
+                                    }
+                                    _ => {
+                                        debug!("{:?}: {}", entry.timestamp, entry.text);
+                                    }
+                                }
+                            }
+                        },
+                        async move {
+                            while let Some(event) = exceptions.next().await {
+                                error!("{:?}", event);
+                            }
+                        },
+                    )
+                    .map(|_| ()))
+                }
+
                 page.execute(EnableParams::builder().build()).await?;
                 page.execute(SetCacheDisabledParams {
                     cache_disabled: true,

crates/harness/runner/src/lib.rs

@@ -6,6 +6,9 @@ mod server_fixture;
 pub mod wasm_server;
 mod ws_proxy;
 
+#[cfg(feature = "debug")]
+mod debug_prelude;
+
 use std::time::Duration;
 
 use anyhow::Result;
@@ -24,6 +27,9 @@ use cli::{Cli, Command};
 use executor::Executor;
 use server_fixture::ServerFixture;
 
+#[cfg(feature = "debug")]
+use crate::debug_prelude::*;
+
 use crate::{cli::Route, network::Network, wasm_server::WasmServer, ws_proxy::WsProxy};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, clap::ValueEnum)]
@@ -113,6 +119,9 @@ impl Runner {
 }
 
 pub async fn main() -> Result<()> {
+    #[cfg(feature = "debug")]
+    tracing_subscriber::fmt::init();
+
     let cli = Cli::parse();
     let mut runner = Runner::new(&cli)?;
 
@@ -227,6 +236,9 @@ pub async fn main() -> Result<()> {
                 // Wait for the network to stabilize
                 tokio::time::sleep(Duration::from_millis(100)).await;
 
+                #[cfg(feature = "debug")]
+                debug!("Starting bench in group {:?}", config.group);
+
                 let (output, _) = tokio::try_join!(
                     runner.exec_p.bench(BenchCmd {
                         config: config.clone(),