Logging | ScyllaDB Docs

Logging¶

The driver uses the tracing crate for all logs.
There are two ways to view the logs:

Create a tracing subscriber to which all logs will be written (recommended).

Enable log feature on tracing crate and use some logger from log ecosystem.
Only do this if you can’t use tracing subscriber for some reason.

Using tracing subscriber¶

To print the logs you can use the default subscriber:

use tracing::info;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    // Install global collector configured based on RUST_LOG env var
    // This collector will receive logs from the driver
    tracing_subscriber::fmt::init();

    let uri = std::env::var("SCYLLA_URI")
        .unwrap_or_else(|_| "127.0.0.1:9042".to_string());

    info!("Connecting to {}", uri);

    let session: Session = SessionBuilder::new().known_node(uri).build().await?;
    session
        .query_unpaged(
            "CREATE KEYSPACE IF NOT EXISTS ks WITH REPLICATION = \
            {'class' : 'NetworkTopologyStrategy', 'replication_factor' : 1}",
            &[],
        )
        .await?;

    // This query should generate a warning message
    session.query_unpaged("USE ks", &[]).await?;

    Ok(())
}

To start this example execute:

RUST_LOG=info cargo run

The full example is available in the examples folder. You can run it from main folder of driver repository using RUST_LOG=trace SCYLLA_URI=<scylla_ip>:9042 cargo run --example logging.

Using log¶

To collect tracing events using log collector you first need to enable log feature on tracing crate. You can use cargo add tracing -F log or edit Cargo.toml:

tracing = { version = "0.1.40" , features = ["log"] }

then you can setup env_logger os some other logger and it will output logs from the driver:

use tracing::info;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    // Setup `log` collector that uses RUST_LOG env variable to configure
    // verbosity.
    env_logger::init();

    let uri = std::env::var("SCYLLA_URI").unwrap_or_else(|_| "127.0.0.1:9042".to_string());
    info!("Connecting to {}", uri);

    let session: Session = SessionBuilder::new().known_node(uri).build().await?;
    session.query_unpaged("CREATE KEYSPACE IF NOT EXISTS examples_ks WITH REPLICATION = {'class' : 'NetworkTopologyStrategy', 'replication_factor' : 1}", &[]).await?;

    session.query_unpaged("USE examples_ks", &[]).await?;

    Ok(())
}

The full example is available in the examples folder. You can run it from main folder of driver repository using RUST_LOG=trace SCYLLA_URI=<scylla_ip>:9042 cargo run --example logging_log.

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