*** title: Rust 'og:site\_name': Unleash 'og:title': Rust SDK description: Rust SDK for integrating with Unleash feature management platform keywords: * unleash * rust * sdk * feature flags * feature toggles max-toc-depth: 3 *** This Rust SDK is designed to help you integrate with Unleash and evaluate feature flags in Rust programs. You can use this client with [Unleash Enterprise](https://www.getunleash.io/pricing?utm_source=readme\&utm_medium=rust) or [Unleash Open Source](https://github.com/Unleash/unleash). ## Client Overview The client is written using async rust. For communicating with the Unleash API surf or reqwest support is built in, or any async HTTP client can be provided by the user if they implement the thin trait used to abstract over the actual client. Examples with async-std (feature 'surf-client') and tokio (feature 'reqwest-client') are in the examples/ in the source tree. See the API docs for more feature information. 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/theads.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. The [crate documentation](https://docs.rs/unleash-api-client/latest/unleash_api_client/) should be consulted for more detail. ### Configuration The easiest way to get started with the `Client` is using the `ClientBuilder`. A simple example is provided: ```rust let config = EnvironmentConfig::from_env()?; let client = client::ClientBuilder::default() .interval(500) .into_client::( &config.api_url, &config.app_name, &config.instance_id, config.secret, )?; client.register().await?; ``` The values required for the `into_client` method are described as follows (in order, as seen above): * `api_url` - The server URL to fetch toggles from. * `app_name` - The name of your application. * `instance_id` - A unique ID, ideally per run. A runtime generated UUID would be a sensible choice here. * `authorization` - An Unleash client secret, if set this will be passed as the authorization header. While the above code shows the usage of the `EnvironmentConfig`, this isn't required and is provided as a convenient way of reading a data from the system environment variables. | EnvironmentConfig Property | Environment Variable | Required? | | -------------------------- | ----------------------- | --------- | | `api_url` | `UNLEASH_API_URL` | Yes | | `app_name` | `UNLEASH_APP_NAME` | Yes | | `instance_id` | `UNLEASH_INSTANCE_ID` | Yes | | `secret` | `UNLEASH_CLIENT_SECRET` | No | Note that if you do use the `EnvironmentConfig` as a way of accessing the system variables, you'll need to ensure that all the environment variables marked as required in the above table are set, or a panic will be raised. The ClientBuilder also has a few builder methods for setting properties which are assumed to have good defaults and generally do not require changing. If you do need to alter these properties you can invoke the following methods on the builder (as seen above with the interval). | Method | Argument | Description | Default | | --------------------------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------- | | interval | u64 | Sets the polling interval to the Unleash server, in milliseconds | 15000ms | | disable\_metric\_submission | N/A | Turns off the metrics submission to Unleash | On | | enable\_string\_features | N/A | By default the Rust SDK requires you to define an enum for feature resolution, turning this on will allow you to resolve your features by string types instead, through the use of the `is_enabled_str` method. Be warned that this is enforced by asserts and calling `is_enabled_str` without turning this on with result in a panic | Off | ## Status Core Unleash API features work, with Rust 1.60 or above. The MSRV for this project is weakly enforced: when a hard dependency raises its version, so will the minimum version tested against, but if older rust versions work for a user, that is not prevented. `time` in particular is known to enforce a 6-month compiler age, so regular increases with the minimum version tested against are expected. Unimplemented Unleash specified features: * local serialised copy of toggles to survive restarts without network traffic. ## Code of Conduct Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms. ## Contributing PR's on Github as normal please. Cargo test to run the test suite, rustfmt code before submitting. To run the functional test suite you need an Unleash API to execute against. For instance, one way: ```shell docker-compose up -d ``` Visit `http://localhost:4242/` and log in with admin + unleash4all, then create a new Backend API token at `http://localhost:4242/admin/api/create-token` for user admin, type Client. Then run the test suite: ```shell UNLEASH_API_URL=http://127.0.0.1:4242/api \ UNLEASH_APP_NAME=fred UNLEASH_INSTANCE_ID=test \ UNLEASH_CLIENT_SECRET="" \ cargo test --features functional -- --nocapture ``` or similar. The functional test suite looks for a manually setup set of features. E.g. log into the Unleash UI on port 4242 and create a feature called `default`.