Tracing and Logging

seleniumbase-rs uses the tracing ecosystem for structured logging. Both the sbrs CLI and the sbrs-mcp server initialize a default tracing_subscriber::fmt() subscriber on startup. This page explains how to control verbosity, configure runtime settings through the environment, and use tracing in your own tests.

Log levels#

Set the RUST_LOG environment variable to control verbosity:

RUST_LOG=info cargo run --bin sbrs -- open https://example.comRUST_LOG=seleniumbase_rs=debug cargo testRUST_LOG=warn cargo run --bin sbrs-mcp

RUST_LOG follows the standard env_logger/tracing-subscriber syntax:

# Show only errors from everything and debug from this crate.RUST_LOG=error,seleniumbase_rs=debug cargo test

Runtime configuration (SB_* environment variables)#

Following Twelve-Factor III (config in the environment), sbrs and the library read runtime settings from SB_* variables:

SB_WEBDRIVER_URL=http://localhost:9515 SB_LOG_LEVEL=debug sbrs open https://example.com

One bad value does not undo the others: with SB_SHUTDOWN_TIMEOUT_SECS=soon sbrs still honours SB_LOG_LEVEL=debug, uses the default timeout and logs a warning that names the variable. A program that builds the configuration itself can do the same with RuntimeConfig::from_env_lenient(), which returns the configuration and the list of problems.

Spans in the library#

Key BaseCase and BrowserSession methods are instrumented with tracing spans so you can see where time is spent:

• BaseCase::new
• BaseCase::with_session
• BaseCase::open, click, type_text, quit
• BrowserSession::connect

Example output:

INFO  seleniumbase_rs::api::base_case: new basecase browser=Chrome mode=UcDEBUG seleniumbase_rs::api::base_case: opening url=https://example.comINFO  seleniumbase_rs::api::base_case: quit

Using tracing in your own tests#

use tracing::{info, instrument};#[instrument]async fn login_flow(sb: &mut seleniumbase_rs::BaseCase) -> Result<(), Box<dyn std::error::Error>> {    info!("starting login flow");    sb.open("https://example.com/login").await?;    // ...    Ok(())}

Tauri multi-profile example#

The Tauri app also initializes tracing_subscriber in src-tauri/src/lib.rs. Its REST API logs each endpoint call so you can correlate UI actions with local HTTP requests.

Error diagnostics#

Errors are emitted as structured tracing::error! events. Each event includes:

Example output:

ERROR seleniumbase_rs::stealth::patcher: binary patch failed for 'chromedriver': failed to read chromedriver: No such file error.category=patcher error.transient=false error.hint="Ensure 'chromedriver' is a valid chromedriver binary and that you have write permissions."

You can also log errors manually:

use seleniumbase_rs::{Result, ResultExt};async fn example() -> Result<()> {    // Log on error but still return the original error:    do_something().await.log_err()?;    // Or attach context and log:    do_something_else()        .sb_context("while loading profile")        .log_err()?;    Ok(())}

Watching async tasks with tokio-console#

When something hangs, tokio-console shows every async task live: which ones are waiting, for how long, and on what.

RUSTFLAGS="--cfg tokio_unstable" cargo run --features tokio-console --bin sbrs -- --headless smoke https://example.com

cargo install --locked tokio-consoletokio-console

It connects to 127.0.0.1:6669. Your own program gets the same when it calls seleniumbase_rs::tracing_util::init_tracing() with the feature on.

Troubleshooting#