Rust SDK reference

Overview

This topic documents how to get started with the server-side Rust SDK, and links to reference information on all of the supported features.

Get started

After you complete the Get started process, follow these instructions to start using the LaunchDarkly SDK in your Rust application.

Install the SDK

First, install the LaunchDarkly SDK as a dependency in your application.

$
cargo add launchdarkly-server-sdk

Initialize the client

Next, import the LaunchDarkly client in your application code:

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use launchdarkly_server_sdk::{Client, ConfigBuilder, ContextBuilder, ServiceEndpointsBuilder};

After you install and import the SDK, create a single, shared instance of the LaunchDarkly client. Specify your SDK key here so that your application is authorized to connect to LaunchDarkly, your application, and your environment.

Once you have created the client, start the client process and wait for the client to initialize. This SDK depends on the tokio crate to provide a default runtime and as such it is a required dependency.

Only create one instance of client.

Here’s how:

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use std::time::Duration;
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#[tokio::main]
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async fn main() {
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    let config = ConfigBuilder::new(&YOUR_SDK_KEY).build();
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    let client = Client::build(config).unwrap();
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    client.start_with_default_executor();
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    let initialized = client
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        .wait_for_initialization(Duration::from_secs(10))
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        .await
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        .unwrap_or(false);
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    if !initialized {
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        panic!("Client failed to successfully initialize");
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    }
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}

To learn more about the specific configuration options available in this SDK, read Config.

Evaluate a context

You can use client to check which variation a particular context will receive for a given feature flag.

Here’s how:

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let context = ContextBuilder::new("example-context-key").build();
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let show_feature = client.bool_variation(&context, "example-flag-key", false);
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if show_feature {
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  # application code to show the feature
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} else {
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  # the code to run if the feature is off
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}

Shut down the client

Shut down the client when your application terminates. To learn more, read Shutting down.

Supported features

This SDK supports the following features:

• Anonymous contexts and users
• Configuration, including
  • Application metadata configuration
• Context configuration
• Evaluating flags
• Flag evaluation reasons
• Flushing events
• Getting all flags
• Identifying and changing contexts
• Logging configuration
• Migrations
• Offline mode
• Private attributes
• Relay Proxy configuration
  • Using proxy mode
  • Using daemon mode
• Secure mode
• Sending custom events
• Service endpoint configuration
• Shutting down
• Test data sources
• Web proxy configuration