Enable debug logs

Sometimes it is easier to troubleshoot applications if all the client library requests and responses are logged to the console. This guide shows you how to enable the logging facilities in the client library.

These logs are meant to be used for debugging applications. The logs include full requests and response messages, which may include sensitive information. If you decide to enable these logs in production, consider the security and privacy implications before doing so.

Prerequisites

This guide uses the Secret Manager API. The same concepts apply to the client libraries for other services. You may want to follow the service quickstart, which shows you how to enable the service.

For complete setup instructions for the Rust libraries, see Setting up your development environment.

Dependencies

You must declare the dependencies in your Cargo.toml file:

cargo add google-cloud-secretmanager-v1 google-cloud-gax

Enable logging

The Rust client libraries use Tokio's tracing crate to collect scoped, structured, and async-aware diagnostics. The tracing separate sources of diagnostics (such as the Rust client libraries) from the components that collect these diagnostics using the Subscriber trait. There are many implementations available for the Subscriber. In this example we will use the fmt subscriber included with the tracing-subscriber crate.

First, add a dependency on the tracing-subscriber crate:

cargo add tracing tracing-subscriber

This example receives the project ID as a function parameter:

/// # Parameters
/// - `project_id`: the id of a Google Cloud project, or its numeric ID.
///   For example: `my-project`.
pub async fn sample(project_id: &str) -> anyhow::Result<()> {

Introduce a few use declarations to make the example more readable:

/// # Parameters
/// - `project_id`: the id of a Google Cloud project, or its numeric ID.
///   For example: `my-project`.
pub async fn sample(project_id: &str) -> anyhow::Result<()> {

Initialize the default tracing subscriber:

    tracing_subscriber::fmt::init();

Initialize a client with tracing enabled. Note the call to .with_tracing():

    let client = SecretManagerService::builder()
        .with_tracing()
        .build()
        .await?;

Then use the client to send a request:

    let mut items = client
        .list_secrets()
        .set_parent(format!("projects/{project_id}"))
        .by_item();
    println!("listing all secrets in project {project_id}");
    while let Some(secret) = items.next().await.transpose()? {
        println!("  {secret:?}");
    }
    println!("DONE");

Expected output

The output (slightly edited for readability) will include a line such as:

2025-11-03T14:17:31.759452Z  INFO list_secrets{self=SecretManagerService ...

This line includes the request:

req=ListSecretsRequest { parent: "projects/... }

and the response:

return=Ok(Response { parts: ..., body: ListSecretsResponse { ...

More information

The default subscriber created via tracing_subscriber::fmt::init() can be configured dynamically using the RUST_LOG environment variable. See its documentation for details.