# feattle
[](https://crates.io/crates/feattle)
[](https://docs.rs/feattle)
[](https://github.com/sitegui/feattle-rs/actions)
[](https://coveralls.io/github/sitegui/feattle-rs?branch=master)
Featture toggles for Rust (called "feattles", for short), extensible and with background
synchronization and administration UI.
### Features
- Feature toggles that synchronize automatically with a backing storage
- Feature toggles can be as simple `bool`, but can also be lists, maps and arbitrary tpes (
(through the [`FeattleValue`] trait).
- Web UI with documentation, change history, validation
- JSON API to read and set the toggles
- Modular and extensible: use as much or as little of the bundled features as you want. Want to
use a different Web UI? A different storage layer? No problem.
### Example
```rust
use rusoto_s3::S3Client;
use rusoto_core::Region;
use feattle::*;
use std::sync::Arc;
/// A struct with your feature toggles: you can use primitive types (like `bool`, `i32`, etc),
/// standard collections (like `Vec`, `BTreeSet`, etc) or any arbitrary type that implements
/// the required trait.
feattles! {
struct MyFeattles {
/// Is this usage considered cool?
is_cool: bool = true,
/// Limit the number of "blings" available.
/// This will not change the number of "blengs", though!
max_blings: i32,
/// List the actions that should not be available
blocked_actions: Vec<String>,
}
}
// Store their values and history in AWS' S3
let s3_client = S3Client::new(Region::default());
let persistence = S3::new(s3_client, "my-bucket".to_owned(), "some/s3/prefix/".to_owned());
// Create a new instance
let my_feattles = Arc::new(MyFeattles::new(persistence));
// Poll the storage in the background
BackgroundSync::new(&my_feattles).spawn();
// Start the admin UI with `warp`
let admin_panel = Arc::new(AdminPanel::new(my_feattles.clone(), "Project Panda - DEV".to_owned()));
tokio::spawn(run_warp_server(admin_panel, ([127, 0, 0, 1], 3030)));
// Read values (note the use of `*`)
assert_eq!(*my_feattles.is_cool(), true);
assert_eq!(*my_feattles.max_blings(), 0);
assert_eq!(*my_feattles.blocked_actions(), Vec::<String>::new());
```
You can run a full example locally with: `cargo run --example full --features='s3 uuid warp'`.
With this code, you'll get an Web Admin UI like:
You can use the UI to edit the current values and see their change history. For example, this
is what you can expect when editing an `enum`:
It also supports complex types with a JSON editor and helpful error diagnostics:
## How it works
The macro will generate a struct with the given name and visibility modifier (assuming private
by default). The generated struct implements [`Feattles`] and also exposes one method for each
feattle.
The methods created for each feattle allow reading their current value. For example, for a
feattle `is_cool: bool`, there will be a method like
`pub fn is_cool(&self) -> MappedRwLockReadGuard<bool>`. Note the use of
[`parking_lot::MappedRwLockReadGuard`] because the interior of the struct is stored behind a `RwLock` to
control concurrent access.
A feattle is created with the syntax `$key: $type [= $default]`. You can use doc coments (
starting with `///`) to describe nicely what they do in your system. You can use any type that
implements [`FeattleValue`] and optionally provide a default. If not provided, the default
will be created with `Default::default()`.
## Minimum supported Rust version
As of this release, the MSRV is 1.51.0, as tested in the CI. A patch release will never require
a newer MSRV.
## Optional features
You can easily declare feattles with your custom types, use another persistance storage logic
or Web Framework (or any at all). For some out-of-the-box functionality, you can activate these
cargo features:
- **uuid**: will add support for [`uuid::Uuid`].
- **s3**: provides [`S3`] to integrate with AWS' S3
- **warp**: provides [`run_warp_server`] for a read-to-use integration with [`warp`]
### Crate's organization
This crate is a simple re-export of these three components:
* `feattle-core`: [](https://crates.io/crates/feattle-core)
* `feattle-sync`: [](https://crates.io/crates/feattle-sync)
* `feattle-ui`: [](https://crates.io/crates/feattle-ui)
Having them separate allows for leaner lower-level integration. If you're creating a crate to
provide a different storage or admin, you just need `feattle-core`.
## License
Licensed under either of
* Apache License, Version 2.0
([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
* MIT license
([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
at your option.
## Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.
See [CONTRIBUTING.md](CONTRIBUTING.md).