Connecting to the cluster

Connecting to the cluster¶

Scylla is a distributed database, which means that it operates on multiple nodes running independently. When creating a Session you can specify a few known nodes to which the driver will try connecting:

use scylla::{Session, SessionBuilder};
use std::error::Error;
use std::time::Duration;
use std::net::{IpAddr, Ipv4Addr, SocketAddr};

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let uri = std::env::var("SCYLLA_URI")
        .unwrap_or_else(|_| "127.0.0.1:9042".to_string());

    let session: Session = SessionBuilder::new()
        .known_node(uri)
        .known_node("127.0.0.72:4321")
        .known_node("localhost:8000")
        .connection_timeout(Duration::from_secs(3))
        .known_node_addr(SocketAddr::new(
            IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)),
            9000,
        ))
        .build()
        .await?;

    Ok(())
}

After successfully connecting to some specified node the driver will fetch topology information about other nodes in this cluster and connect to them as well.

Scylla Serverless is an elastic and dynamic deployment model. When creating a Session you need to specify the secure connection bundle as follows:

use std::path::Path;
use std::error::Error;
use scylla::CloudSessionBuilder;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let session = CloudSessionBuilder::new(Path::new("config_data.yaml"))
        .unwrap()
        .build()
        .await
        .unwrap();

    Ok(())
}

Note that the bundle file will be provided after the serverless cluster is created. Here is an example of a configuration file for a serverless cluster:

datacenters:
  datacenter1:
    certificateAuthorityData: CERTIFICATE_DATA
    server: 127.0.1.1:9142
    nodeDomain: cql.cluster-id.scylla.com
    insecureSkipTlsVerify: false
authInfos:
  default:
    clientCertificateData: CERTIFICATE_DATA
    clientKeyData: KEY_DATA
    username: scylladb
    password: scylladb
contexts:
  default:
    datacenterName: datacenter1
    authInfoName: default
currentContext: default

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