# Flipt Rust
[](https://crates.io/crates/flipt)
This directory contains the Rust source code for the Flipt [server-side](https://www.flipt.io/docs/integration/server/rest) client.
## Documentation
API documentation is available at <https://www.flipt.io/docs/reference/overview>.
## Installation
```sh
cargo add flipt
```
## Usage
In your Rust code you can import this client and use it as so:
```rust
use std::collections::HashMap;
use flipt::api::FliptClient;
use flipt::evaluation::models::EvaluationRequest;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
let client = FliptClient::default();
let mut context: HashMap<String, String> = HashMap::new();
context.insert("fizz".into(), "buzz".into());
let variant_result = client
.evaluation
.variant(&EvaluationRequest {
namespace_key: "default".into(),
flag_key: "flag1".into(),
entity_id: "entity".into(),
context: context.clone(),
reference: None,
})
.await
.unwrap();
print!("{:?}", variant_result);
```
There is a more detailed example in the [examples](./examples) directory.
## Setting HTTP Headers
You can set custom HTTP headers for the client by using the `with_headers` method in the `ConfigBuilder`.
```rust
let client = FliptClient::new(ConfigBuilder::default().with_headers(HeaderMap::new()).build());
```
### Flipt V2 Environment Support
Flipt V2 introduces the concept of [environments](https://docs.flipt.io/v2/concepts#environments). This client supports evaluation of flags in a specific environment by using the `X-Flipt-Environment` header.
```rust
let client = FliptClient::new(ConfigBuilder::default().with_headers(HeaderMap::from_iter([("X-Flipt-Environment".into(), "production".into())])).build());
```