fluxgate 1.0.0

Client for the FluxGate feature toggle edge server, over OFREP, with an optional OpenFeature provider
Documentation

fluxgate

Rust client for the FluxGate feature toggle edge server. It evaluates flags over OFREP (the OpenFeature Remote Evaluation Protocol), authenticated with a FluxGate client's SDK key.

[dependencies]
fluxgate = "1"

use fluxgate::{EvaluationContext, FluxGateClient};

let fluxgate = FluxGateClient::new("https://edge.example.com", &std::env::var("FLUXGATE_SDK_KEY").unwrap())?;
let user = EvaluationContext::new("user-1").with("country", "CA").with("user_tier", "plus");

if fluxgate.is_enabled("new-checkout", &user).await {
    // ...
}

let theme = fluxgate.evaluate("checkout-theme", "classic".to_owned(), &user).await;
println!("{} (variant {:?}, reason {})", theme.value, theme.variant, theme.reason);

What's in the crate

  • FluxGateClient: one OFREP call per flag and context, with retries, timeouts and a 30-second cache. Evaluations never fail. On any error they return your default value with an error_code. The client needs a Tokio runtime and is cheap to clone.
  • FlagSnapshot, from client.watch(context): loads every flag for one context in one call and polls every 30 seconds with If-None-Match, so an unchanged flag set costs a 304. Reads are synchronous. subscribe() notifies you of changes.
  • fluxgate::blocking (feature blocking): the same API for code without an async runtime.
  • fluxgate::openfeature::FluxGateProvider (feature openfeature): an OpenFeature provider for the open-feature crate.
Feature Default
rustls yes TLS through rustls.
native-tls no TLS through the operating system's library. Use with default-features = false.
blocking no The synchronous client.
openfeature no The OpenFeature provider.

Rust 1.85 or later.

SDK keys

Create a Backend client in the FluxGate admin UI (Clients). Its SDK key is <clientId>.<apiKey>. Keep it secret.

How evaluation works

  • Every evaluation needs a targeting key, the ID that decides the user's bucket in percentage splits. EvaluationContext::new("user-1") sets it.
  • The default value sets the expected type: a bool, String, i64, f64 or serde_json::Value (Value::Null accepts any flag). A boolean flag read with a string default is a TYPE_MISMATCH.
  • A flag that is disabled or not deployed for the client's environment answers false with no variant, whatever its type. For non-boolean reads that yields your default value.
  • The edge remembers the variant it first served to a targeting key. After you change a flag's rules, a user who already got an answer can keep it.

See the repository for samples that run against a local FluxGate stack.

License

Apache License 2.0