feattle

Featture toggles for Rust, extensible and with background synchronization and administration UI.

Example

use rusoto_s3::S3Client;
use rusoto_core::Region;
use feattle::*;
use std::sync::Arc;

/// A struct with your feature toggles
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());

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().

Updating values

This crate only disposes of low-level methods to load current feattles with [Feattles::reload()] and update their values with [Feattles::update()]. Please look for the crates feattle-sync and feattle-ui for higher-level functionalities.

Limitations

Due to some restrictions on how the macro is written, you can only use [feattles!] once per module. For example, the following does not compile:

use feattle_core::feattles;

feattles! { struct A { } }
feattles! { struct B { } }

You can work around this limitation by creating a sub-module and then re-exporting the generated struct. Note the use of pub struct in the second case.

use feattle_core::feattles;

feattles! { struct A { } }

mod b {
    use feattle_core::feattles;
    feattles! { pub struct B { } }
}

use b::B;

Optional 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]

Organization

feattle-core:
feattle-sync:
feattle-ui:
feattle:

License

Licensed under either of

Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (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.

feattle 0.2.3