The Flagship platform now ships an official Rust SDK, exposing its feature‑flag capabilities to async Rust services via the OpenFeature abstraction. Engineers can pull the cloudflare-flagship crate, configure client credentials, and start querying flags with the same targeting logic used by other Flagship SDKs.
How the SDK Fits Into Your Stack
After adding the crate with cargo add cloudflare-flagship, you instantiate a FlagshipClientOptions builder, supply your application ID, account ID, and API token, and hand the resulting options to FlagshipServerProvider. The provider is registered on an OpenFeature instance, after which flag values are retrieved with standard OpenFeature calls such as get_bool_value. The SDK defaults to HTTP evaluation, but you can enable local evaluation to download flag definitions once and resolve them in‑process.
let options = FlagshipClientOptions::builder()
.app_id("<APP_ID>")
.account_id("<ACCOUNT_ID>")
.auth_token("<API_TOKEN>")
.build()?;
let mut api = OpenFeature::default();
api.set_provider(FlagshipServerProvider::new(options)?).await;
let context = EvaluationContext::default().with_targeting_key("user-42");
let enabled = api.create_client()
.get_bool_value("new-checkout", Some(&context), None)
.await
.unwrap_or(false);
Operational Considerations
The SDK requires Rust 1.88+ and a Tokio runtime, so ensure your build pipeline targets that version and that your service already runs on Tokio or can add it without major refactoring. Local evaluation reduces latency and external dependency on Flagship’s API, but it introduces a cache that must be refreshed periodically; the SDK documentation describes the refresh behavior. Logging and telemetry hooks are exposed, allowing you to integrate with existing observability pipelines.
Security Implications
Authentication relies on an API token supplied to the client options. Treat that token as a secret: store it in a vault or environment variable with restricted access, and avoid hard‑coding it. When using the default HTTP mode, each flag evaluation triggers a network request, exposing the token on the wire; ensure TLS is enforced (the SDK uses HTTPS by default). Switching to local evaluation limits exposure by keeping the token in memory only during the initial download, but the initial fetch still requires secure handling.
Related CloudNinjas coverage: hands-on guides.
What This Means For Practitioners
Adopting the Rust Flagship SDK lets you embed feature‑flag decisions directly in async Rust services without external wrappers. Evaluate whether the added dependency aligns with your runtime constraints, and decide between HTTP‑based or local evaluation based on latency requirements and token exposure concerns. Monitor the SDK’s refresh cycle and integrate its telemetry into your observability stack to detect misconfigurations early. Finally, keep the Rust toolchain and the SDK version up to date to benefit from security patches and performance improvements.
