Instrumentation

In order to instrument our backend, we are going to use the tracing crate.

Let's add this dependency to the Cargo.toml file of our Shuttle crate:

tracing = "0.1"

Now, let's add some instrumentation to our main.rs file. Feel free to add as many logs as you want. For example:

#![allow(unused)]
fn main() {
#[get("/version")]
async fn version(db: actix_web::web::Data<sqlx::PgPool>) -> String {
    // NOTE: added line below:
    tracing::info!("Getting version");
    let result: Result<String, sqlx::Error> = sqlx::query_scalar("SELECT version()")
        .fetch_one(db.get_ref())
        .await;

    match result {
        Ok(version) => version,
        Err(e) => format!("Error: {:?}", e),
    }
}
}

If you run the application now, and hit the version endpoint, you should see something like this in the logs of your terminal:

2023-07-01T19:47:32.836809924+02:00  INFO api_shuttle: Getting version

Log level

By default, the log level is set to info. This means that all logs with a level of info or higher will be displayed. If you want to change the log level, you can do so by setting the RUST_LOG environment variable. For example, if you want to see all logs, you can set the log level to trace:

RUST_LOG=trace cargo shuttle run

Let's commit our changes:

git add .
git commit -m "added instrumentation"