Shuttle Persist

The persist plugin allows data to be persisted in a key-value store, which is backed by a struct type. The struct implements serde::Serialize for serialization (prepare data for saving or transmission) and serde::Deserialize for deserialization (load data to memory, either from storage or fetched via the network). The persist plugin is useful for saving and retrieving data when it is not desired to hard code that data into the app. An example is saved settings for a Discord bot that need to remain the same between updates. State data, used in web frameworks such as Axum and Rocket, is also a good candidate for use of the persist plugin.

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Usage

To use the persist plugin, add shuttle-persist to the dependencies of your service with cargo add shuttle-persist. Then, annotate your shuttle_runtime::main function by adding the shuttle-persist::Persist attribute as a parameter. This will give a PersistInstance. There are six methods available to PersistInstance, providing tools to manage the data stored within. The methods are:

• clear(): removes the keys within the PersistInstance
• list(): returns a vector of strings containing all the keys associated with a PersistInstance
• load(): loads a value from a key stored within the PersistInstance
• new(): constructs a new PersistInstance along with its associated storage folder
• save(): saves a key-value pair into the PersistInstance
• remove(): deletes a key from the PersistInstance

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Example

This snippet shows a Shuttle rocket main function that uses the shuttle_persist::Persist attribute to provision and get access to a PersistInstance. In this example,the PersistInstance is used to store state for the app.

#[shuttle_runtime::main]
async fn rocket(
    #[shuttle_persist::Persist] persist: PersistInstance,
) -> ShuttleRocket {
    let state = MyState { persist };
    let rocket = rocket::build()
        .mount("/", routes![retrieve, add])
        .manage(state);

    Ok(rocket.into())
}

The full example can be found on GitHub.