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Logging

    • Developer Preview
      +
      The Rust SDK logs events. It has no hard dependency on a specific logger implementation, but you should add one you are comfortable with.

      Configuring Logging

      The Couchbase Rust SDK has no hard dependency on a specific logger implementation. It uses the Rust log facade and will use the logger that has been configured in the environment. If no logger is configured then no logging will occur.

      Rust has several logging implementations available including env_logger.

      Logger example with env_logger

      To enable logging you must add a logging crate to your Cargo.toml file:

      [dependencies]
env_logger = "0.11"

      You must also then register a global logger to consume the log messages. The simplest example of using env_logger is simply to add the following before executing any Couchbase SDK code:

      env_logger::init();

      This will create a logger which logs at the level specified by the RUST_LOG environment variable, as an example:

      $ RUST_LOG='couchbase=trace' cargo run

      You can also configure env_logger in a number of ways to customise the logger output, for example:

      env_logger::Builder::new()
    .format(|buf, record| {
        writeln!(
            buf,
            "{}:{} {} [{}] - {}",
            record.file().unwrap_or("unknown"),
            record.line().unwrap_or(0),
            chrono::Local::now().format("%Y-%m-%dT%H:%M:%S%.3f"),
            record.level(),
            record.args()
        )
    })
    .filter(Some("rustls"), LevelFilter::Warn)
    .init();

      When RUST_LOG is set to debug and the following code is run then the SDK will generate a number of log messages:

      let username = "<your-username>";
let password = "<your-password>";

let cluster = timeout(
    Duration::from_secs(60),
    Cluster::connect(
        // For a secure cluster connection, use `couchbases://<your-cluster-ip>` instead.
        "couchbase://localhost",
        ClusterOptions::new(Authenticator::PasswordAuthenticator(
            PasswordAuthenticator::new(username, password),
        )),
    ),
)
.await?;

cluster
    .wait_until_ready(WaitUntilReadyOptions::default())
    .await?;
      Logger output [Click to open or collapse the output] 
      .../couchbase-core-1.0.0-beta.1/src/agent.rs:466 2025-10-14T08:59:14.402 [INFO] - Creating new agent couchbase-rs-core 1.0.0-beta.1 couchbase-core-1.0.0-beta.1/src/kvclient.rs:233 2025-10-14T08:59:14.405 [DEBUG] - Kvclient 63cd285f-f1a9-4f76-bdd0-5fe917b49004 assigning client id e55cef70-f1aa-43c0-9374-c0e696e83ee8 for 192.168.107.128:11210 couchbase-core-1.0.0-beta.1/src/kvclient.rs:349 2025-10-14T08:59:14.718 [INFO] - Enabled hello features: [SeqNo, Xattr, Xerror, SelectBucket, Snappy, Json, Duplex, UnorderedExec, Durations, AltRequests, SyncReplication, Collections, SnappyEverywhere, PreserveExpiry, CreateAsDeleted, ReplaceBodyWithXattr, ClusterMapKnownVersion, DedupeNotMyVbucketClustermap, ClusterMapChangeNotificationBrief]
.../couchbase-core-1.0.0-beta.1/src/memdx/client.rs:400 2025-10-14T08:59:14.719 [DEBUG] - Client e55cef70-f1aa-43c0-9374-c0e696e83ee8 closing couchbase-core-1.0.0-beta.1/src/memdx/client.rs:423 2025-10-14T08:59:14.719 [DEBUG] - Client e55cef70-f1aa-43c0-9374-c0e696e83ee8 exiting couchbase-core-1.0.0-beta.1/src/kvclientmanager.rs:190 2025-10-14T08:59:14.719 [DEBUG] - Reconfiguring client manager couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:670 2025-10-14T08:59:14.719 [DEBUG] - Creating new client pool 6d28241a-f6f1-455c-a43a-c831d5e7e126 for 192.168.107.129:11210 couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:615 2025-10-14T08:59:14.719 [DEBUG] - Client pool 6d28241a-f6f1-455c-a43a-c831d5e7e126 creating new client with id 00453726-ac2c-4da2-89ca-55ea4cf3040b couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:670 2025-10-14T08:59:14.719 [DEBUG] - Creating new client pool 44ef4d63-d7d4-4985-8f61-a871c2617e6b for 192.168.107.128:11210 couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:615 2025-10-14T08:59:14.719 [DEBUG] - Client pool 44ef4d63-d7d4-4985-8f61-a871c2617e6b creating new client with id a7f35a19-a61b-4b06-9408-acdc89ad59af couchbase-core-1.0.0-beta.1/src/agent.rs:678 2025-10-14T08:59:14.720 [DEBUG] - Agent created, 1 strong references couchbase-core-1.0.0-beta.1/src/agent.rs:739 2025-10-14T08:59:14.719 [DEBUG] - Bootstrap client 63cd285f-f1a9-4f76-bdd0-5fe917b49004 closed couchbase-core-1.0.0-beta.1/src/memdx/client.rs:162 2025-10-14T08:59:14.720 [DEBUG] - e55cef70-f1aa-43c0-9374-c0e696e83ee8 read loop shut down couchbase-core-1.0.0-beta.1/src/kvclient.rs:233 2025-10-14T08:59:14.720 [DEBUG] - Kvclient a7f35a19-a61b-4b06-9408-acdc89ad59af assigning client id 83de7fed-0a80-474f-b8a8-9cd98d0fbe1c for 192.168.107.128:11210 couchbase-core-1.0.0-beta.1/src/kvclient.rs:233 2025-10-14T08:59:14.720 [DEBUG] - Kvclient 00453726-ac2c-4da2-89ca-55ea4cf3040b assigning client id e8f44e82-85b2-4653-b99e-a073d6f3ac3c for 192.168.107.129:11210 reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.720 [DEBUG] - starting new connection: http://192.168.107.128:8093/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.720 [DEBUG] - starting new connection: http://192.168.107.129:8093/
.../couchbase-core-1.0.0-beta.1/src/agent.rs:466 2025-10-14T08:59:14.402 [INFO] - Creating new agent couchbase-rs-core 1.0.0-beta.1
.../couchbase-core-1.0.0-beta.1/src/kvclient.rs:233 2025-10-14T08:59:14.405 [DEBUG] - Kvclient 63cd285f-f1a9-4f76-bdd0-5fe917b49004 assigning client id e55cef70-f1aa-43c0-9374-c0e696e83ee8 for 192.168.107.128:11210
.../couchbase-core-1.0.0-beta.1/src/kvclient.rs:349 2025-10-14T08:59:14.718 [INFO] - Enabled hello features: [SeqNo, Xattr, Xerror, SelectBucket, Snappy, Json, Duplex, UnorderedExec, Durations, AltRequests, SyncReplication, Collections, SnappyEverywhere, PreserveExpiry, CreateAsDeleted, ReplaceBodyWithXattr, ClusterMapKnownVersion, DedupeNotMyVbucketClustermap, ClusterMapChangeNotificationBrief]
.../couchbase-core-1.0.0-beta.1/src/memdx/client.rs:400 2025-10-14T08:59:14.719 [DEBUG] - Client e55cef70-f1aa-43c0-9374-c0e696e83ee8 closing
.../couchbase-core-1.0.0-beta.1/src/memdx/client.rs:423 2025-10-14T08:59:14.719 [DEBUG] - Client e55cef70-f1aa-43c0-9374-c0e696e83ee8 exiting
.../couchbase-core-1.0.0-beta.1/src/kvclientmanager.rs:190 2025-10-14T08:59:14.719 [DEBUG] - Reconfiguring client manager
.../couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:670 2025-10-14T08:59:14.719 [DEBUG] - Creating new client pool 6d28241a-f6f1-455c-a43a-c831d5e7e126 for 192.168.107.129:11210
.../couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:615 2025-10-14T08:59:14.719 [DEBUG] - Client pool 6d28241a-f6f1-455c-a43a-c831d5e7e126 creating new client with id 00453726-ac2c-4da2-89ca-55ea4cf3040b
.../couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:670 2025-10-14T08:59:14.719 [DEBUG] - Creating new client pool 44ef4d63-d7d4-4985-8f61-a871c2617e6b for 192.168.107.128:11210
.../couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:615 2025-10-14T08:59:14.719 [DEBUG] - Client pool 44ef4d63-d7d4-4985-8f61-a871c2617e6b creating new client with id a7f35a19-a61b-4b06-9408-acdc89ad59af
.../couchbase-core-1.0.0-beta.1/src/agent.rs:678 2025-10-14T08:59:14.720 [DEBUG] - Agent created, 1 strong references
.../couchbase-core-1.0.0-beta.1/src/agent.rs:739 2025-10-14T08:59:14.719 [DEBUG] - Bootstrap client 63cd285f-f1a9-4f76-bdd0-5fe917b49004 closed
.../couchbase-core-1.0.0-beta.1/src/memdx/client.rs:162 2025-10-14T08:59:14.720 [DEBUG] - e55cef70-f1aa-43c0-9374-c0e696e83ee8 read loop shut down
.../couchbase-core-1.0.0-beta.1/src/kvclient.rs:233 2025-10-14T08:59:14.720 [DEBUG] - Kvclient a7f35a19-a61b-4b06-9408-acdc89ad59af assigning client id 83de7fed-0a80-474f-b8a8-9cd98d0fbe1c for 192.168.107.128:11210
.../couchbase-core-1.0.0-beta.1/src/kvclient.rs:233 2025-10-14T08:59:14.720 [DEBUG] - Kvclient 00453726-ac2c-4da2-89ca-55ea4cf3040b assigning client id e8f44e82-85b2-4653-b99e-a073d6f3ac3c for 192.168.107.129:11210
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.720 [DEBUG] - starting new connection: http://192.168.107.128:8093/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.720 [DEBUG] - starting new connection: http://192.168.107.129:8093/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.720 [DEBUG] - starting new connection: http://192.168.107.128:8094/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.721 [DEBUG] - starting new connection: http://192.168.107.129:8094/
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:395 2025-10-14T08:59:14.721 [DEBUG] - Pinging pool kvep-192.168.107.129-8091 with 1 clients
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:441 2025-10-14T08:59:14.721 [DEBUG] - Client 00453726-ac2c-4da2-89ca-55ea4cf3040b is not connected
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:395 2025-10-14T08:59:14.721 [DEBUG] - Pinging pool kvep-192.168.107.128-8091 with 1 clients
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:441 2025-10-14T08:59:14.721 [DEBUG] - Client a7f35a19-a61b-4b06-9408-acdc89ad59af is not connected
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:324 2025-10-14T08:59:14.721 [DEBUG] - Retrying { operation: wait_until_ready, id: , is_idempotent: true, retry_attempts: 1, retry_reasons: NOT_READY } after 1ms due to NOT_READY
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.722 [DEBUG] - starting new connection: http://192.168.107.129:8093/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.723 [DEBUG] - starting new connection: http://192.168.107.128:8093/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.723 [DEBUG] - starting new connection: http://192.168.107.128:8094/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.723 [DEBUG] - starting new connection: http://192.168.107.129:8094/
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:395 2025-10-14T08:59:14.723 [DEBUG] - Pinging pool kvep-192.168.107.128-8091 with 1 clients
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:441 2025-10-14T08:59:14.723 [DEBUG] - Client a7f35a19-a61b-4b06-9408-acdc89ad59af is not connected
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:395 2025-10-14T08:59:14.723 [DEBUG] - Pinging pool kvep-192.168.107.129-8091 with 1 clients
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:441 2025-10-14T08:59:14.723 [DEBUG] - Client 00453726-ac2c-4da2-89ca-55ea4cf3040b is not connected
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:324 2025-10-14T08:59:14.723 [DEBUG] - Retrying { operation: wait_until_ready, id: , is_idempotent: true, retry_attempts: 2, retry_reasons: NOT_READY } after 2ms due to NOT_READY
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.964 [DEBUG] - starting new connection: http://192.168.107.129:8093/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.965 [DEBUG] - starting new connection: http://192.168.107.128:8093/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.965 [DEBUG] - starting new connection: http://192.168.107.128:8094/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:14.965 [DEBUG] - starting new connection: http://192.168.107.129:8094/
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:395 2025-10-14T08:59:14.965 [DEBUG] - Pinging pool kvep-192.168.107.128-8091 with 1 clients
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:441 2025-10-14T08:59:14.965 [DEBUG] - Client a7f35a19-a61b-4b06-9408-acdc89ad59af is not connected
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:395 2025-10-14T08:59:14.965 [DEBUG] - Pinging pool kvep-192.168.107.129-8091 with 1 clients
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:441 2025-10-14T08:59:14.965 [DEBUG] - Client 00453726-ac2c-4da2-89ca-55ea4cf3040b is not connected
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:324 2025-10-14T08:59:14.965 [DEBUG] - Retrying { operation: wait_until_ready, id: , is_idempotent: true, retry_attempts: 3, retry_reasons: NOT_READY } after 4ms due to NOT_READY
.../couchbase-core-1.0.0-beta.1/src/kvclient.rs:349 2025-10-14T08:59:15.194 [INFO] - Enabled hello features: [SeqNo, Xattr, Xerror, SelectBucket, Snappy, Json, Duplex, UnorderedExec, Durations, AltRequests, SyncReplication, Collections, SnappyEverywhere, PreserveExpiry, CreateAsDeleted, ReplaceBodyWithXattr, ClusterMapKnownVersion, DedupeNotMyVbucketClustermap, ClusterMapChangeNotificationBrief]
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:15.194 [DEBUG] - starting new connection: http://192.168.107.128:8093/
.../couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:475 2025-10-14T08:59:15.194 [DEBUG] - Client pool 6d28241a-f6f1-455c-a43a-c831d5e7e126 created client successfully: 00453726-ac2c-4da2-89ca-55ea4cf3040b
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:15.194 [DEBUG] - starting new connection: http://192.168.107.129:8093/
.../couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:487 2025-10-14T08:59:15.194 [DEBUG] - Client pool 6d28241a-f6f1-455c-a43a-c831d5e7e126 changing client 00453726-ac2c-4da2-89ca-55ea4cf3040b connection state to Connected
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:15.195 [DEBUG] - starting new connection: http://192.168.107.128:8094/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:15.195 [DEBUG] - starting new connection: http://192.168.107.129:8094/
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:395 2025-10-14T08:59:15.195 [DEBUG] - Pinging pool kvep-192.168.107.128-8091 with 1 clients
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:441 2025-10-14T08:59:15.195 [DEBUG] - Client a7f35a19-a61b-4b06-9408-acdc89ad59af is not connected
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:395 2025-10-14T08:59:15.195 [DEBUG] - Pinging pool kvep-192.168.107.129-8091 with 1 clients
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:324 2025-10-14T08:59:15.195 [DEBUG] - Retrying { operation: wait_until_ready, id: , is_idempotent: true, retry_attempts: 4, retry_reasons: NOT_READY } after 8ms due to NOT_READY
.../couchbase-core-1.0.0-beta.1/src/kvclient.rs:349 2025-10-14T08:59:15.196 [INFO] - Enabled hello features: [SeqNo, Xattr, Xerror, SelectBucket, Snappy, Json, Duplex, UnorderedExec, Durations, AltRequests, SyncReplication, Collections, SnappyEverywhere, PreserveExpiry, CreateAsDeleted, ReplaceBodyWithXattr, ClusterMapKnownVersion, DedupeNotMyVbucketClustermap, ClusterMapChangeNotificationBrief]
.../couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:475 2025-10-14T08:59:15.196 [DEBUG] - Client pool 44ef4d63-d7d4-4985-8f61-a871c2617e6b created client successfully: a7f35a19-a61b-4b06-9408-acdc89ad59af
.../couchbase-core-1.0.0-beta.1/src/kvclientpool.rs:487 2025-10-14T08:59:15.196 [DEBUG] - Client pool 44ef4d63-d7d4-4985-8f61-a871c2617e6b changing client a7f35a19-a61b-4b06-9408-acdc89ad59af connection state to Connected
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:15.205 [DEBUG] - starting new connection: http://192.168.107.129:8094/
.../reqwest-0.12.23/src/connect.rs:882 2025-10-14T08:59:15.206 [DEBUG] - starting new connection: http://192.168.107.128:8094/
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:395 2025-10-14T08:59:15.206 [DEBUG] - Pinging pool kvep-192.168.107.128-8091 with 1 clients
.../couchbase-core-1.0.0-beta.1/src/diagnosticscomponent.rs:395 2025-10-14T08:59:15.206 [DEBUG] - Pinging pool kvep-192.168.107.129-8091 with 1 clients