windmill/system_prompts/auto-generated/skills/write-script-rust/SKILL.md

name, description

name	description
write-script-rust	MUST use when writing Rust scripts.

CLI Commands

Place scripts in a folder. After writing, run:

• wmill script generate-metadata - Generate .script.yaml and .lock files
• wmill sync push - Deploy to Windmill

Use wmill resource-type list --schema to discover available resource types.

Rust

Structure

The script must contain a function called main with proper return type:

use anyhow::anyhow;
use serde::Serialize;

#[derive(Serialize, Debug)]
struct ReturnType {
    result: String,
    count: i32,
}

fn main(param1: String, param2: i32) -> anyhow::Result<ReturnType> {
    Ok(ReturnType {
        result: param1,
        count: param2,
    })
}

Important:

• Arguments should be owned types
• Return type must be serializable (#[derive(Serialize)])
• Return type is anyhow::Result<T>

Dependencies

Packages must be specified with a partial cargo.toml at the beginning of the script:

//! ```cargo
//! [dependencies]
//! anyhow = "1.0.86"
//! reqwest = { version = "0.11", features = ["json"] }
//! tokio = { version = "1", features = ["full"] }
//! ```

use anyhow::anyhow;
// ... rest of the code

Note: Serde is already included, no need to add it again.

Async Functions

If you need to handle async functions (e.g., using tokio), keep the main function sync and create the runtime inside:

//! ```cargo
//! [dependencies]
//! anyhow = "1.0.86"
//! tokio = { version = "1", features = ["full"] }
//! reqwest = { version = "0.11", features = ["json"] }
//! ```

use anyhow::anyhow;
use serde::Serialize;

#[derive(Serialize, Debug)]
struct Response {
    data: String,
}

fn main(url: String) -> anyhow::Result<Response> {
    let rt = tokio::runtime::Runtime::new()?;
    rt.block_on(async {
        let resp = reqwest::get(&url).await?.text().await?;
        Ok(Response { data: resp })
    })
}