Crate unleash_api_client

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Unleash is a feature flag API system. This is a client for it to facilitate using the API to control features in Rust programs.

§Client overview

The client is written using async. Any std compatible async runtime should be compatible. Examples with async-std and tokio are in the examples/ in the source tree. To use it in a sync program, run an async executor and block_on() the relevant calls. As the client specification requires sending background metrics to the API, you will need to arrange to call the poll_for_updates method from a thread as demonstrated in examples/threads.rs. The unleash defined strategies are included, to support custom strategies use the ClientBuilder and call the strategy method to register your custom strategy memoization function.

use std::collections::hash_map::HashMap;
use std::collections::hash_set::HashSet;
use std::hash::BuildHasher;
use std::time::Duration;
use async_std::task;
use futures_timer::Delay;
use serde::{Deserialize, Serialize};
use enum_map::Enum;
use unleash_api_client::client;
use unleash_api_client::config::EnvironmentConfig;
use unleash_api_client::context::Context;
use unleash_api_client::strategy;
fn _reversed_uids<S: BuildHasher>(
    parameters: Option<HashMap<String, String, S>>,
) -> strategy::Evaluate {
    let mut uids: HashSet<String> = HashSet::new();
    if let Some(parameters) = parameters {
        if let Some(uids_list) = parameters.get("userIds") {
            for uid in uids_list.split(',') {
                uids.insert(uid.chars().rev().collect());
            }
        }
    }
    Box::new(move |context: &Context| -> bool {
        context
            .user_id
            .as_ref()
            .map(|uid| uids.contains(uid))
            .unwrap_or(false)
    })
}
#[allow(non_camel_case_types)]
#[derive(Debug, Deserialize, Serialize, Enum, Clone)]
enum UserFeatures {
    default
}
fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync + 'static>> {
    let _ = simple_logger::init();
    task::block_on(async {
        let config = EnvironmentConfig::from_env()?;
        let client = client::ClientBuilder::default()
            .strategy("reversed", Box::new(&_reversed_uids))
            .into_client::<UserFeatures, unleash_api_client::prelude::DefaultClient>(
                &config.api_url,
                &config.app_name,
                &config.instance_id,
               config.secret,
            )?;
        client.register().await?;
        futures::future::join(client.poll_for_updates(), async {
            // Ensure we have initial load of features completed
            Delay::new(Duration::from_millis(500)).await;
            assert_eq!(true, client.is_enabled(UserFeatures::default, None, false));
            // ... serve more requests
            client.stop_poll().await;
        }).await;
        Ok(())
    })
}

Previously there was a Re-export of enum_map::Enum - this trait is part of our public API. But there is a bug: https://gitlab.com/KonradBorowski/enum-map/-/issues/22 so instead you must match the version in your dependencies.

§Crate features

  • backtrace - Enable backtrace feature in anyhow (nightly only)
  • default - The default feature enables the async-std/surf feature.
  • functional - Only relevant to developers: enables the functional test suite.
  • reqwest-client - Enables reqwest with OpenSSL TLS support
  • reqwest-client-rustls - Enables reqwest with RusTLS support
  • strict - Turn unexpected fields in API responses into errors
  • surf-client - Enables Surf as the HTTP client to retrieve flags

Re-exports§

Modules§