Are there any Rust crates for scraping that handle rotating user agents?

Yes, there are several Rust crates available for web scraping, and while they may not provide built-in functionality for rotating user agents directly, you can achieve this by integrating them with additional code to handle the rotation of user agents.

One of the most popular Rust crates for web scraping is reqwest, which is an HTTP client that can be used for making requests to web pages. You can integrate reqwest with a list of user agents and implement the logic to rotate them for each request. Here's a high-level example of how you might do this:

Add reqwest to your Cargo.toml:

[dependencies]
reqwest = "0.11"
rand = "0.8"

Here is a sample Rust code that demonstrates how to use reqwest with rotating user agents:

use reqwest::header::{HeaderMap, USER_AGENT};
use rand::seq::SliceRandom;
use std::error::Error;

// Define a list of user agents to rotate through.
const USER_AGENTS: &[&str] = &[
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3",
    // Add more user agents as needed
];

async fn scrape_with_rotating_user_agents(url: &str) -> Result<(), Box<dyn Error>> {
    // Create a client instance.
    let client = reqwest::Client::new();

    // Create a mutable HeaderMap to store the user agent.
    let mut headers = HeaderMap::new();

    // Randomly select a user agent from the list.
    let user_agent = *USER_AGENTS.choose(&mut rand::thread_rng()).unwrap();
    headers.insert(USER_AGENT, user_agent.parse().unwrap());

    // Make a GET request with the selected user agent.
    let response = client.get(url).headers(headers).send().await?;

    // Process the response as needed (for example, print the status code and the text).
    println!("Status: {}", response.status());
    println!("Body: {:?}", response.text().await?);

    Ok(())
}

#[tokio::main]
async fn main() {
    let url = "http://example.com"; // Replace with the URL you want to scrape
    if let Err(e) = scrape_with_rotating_user_agents(url).await {
        eprintln!("Error: {}", e);
    }
}

In this code, we define a list of user agent strings (USER_AGENTS) and then randomly select one using the rand crate when making a request with the reqwest client. The HeaderMap is used to set the USER_AGENT header for the request.

Remember that web scraping should be done responsibly and in compliance with the target website's terms of service. Rotating user agents can be seen as an attempt to evade detection and might be against the terms of service of some websites. Always check the robots.txt file of the website and respect their scraping policies.