How do I configure custom headers in requests made by headless_chrome (Rust)?

In Rust, when you're using a headless Chrome browser, you're likely using the Selenium WebDriver or a library like Fantoccini, which is an async WebDriver client for Rust.

Here's how you can configure custom headers in requests made by a headless Chrome browser in Rust using Fantoccini:

First, you need to make sure that you have the following dependencies in your Cargo.toml:

[dependencies]
fantoccini = "0.22"
tokio = { version = "1", features = ["full"] }
webdriver = "0.42"

Then you can write the Rust code to launch a headless Chrome browser and configure custom headers:

use fantoccini::{ClientBuilder, Locator};
use tokio;

#[tokio::main]
async fn main() -> Result<(), fantoccini::error::CmdError> {
    // Start the WebDriver client
    let mut caps = serde_json::map::Map::new();
    let opts = serde_json::json!({ "args": ["--headless"], "extensions": [] });

    caps.insert(
        String::from("goog:chromeOptions"),
        serde_json::Value::Object(opts),
    );

    let client = ClientBuilder::native()
        .capabilities(caps)
        .connect("http://localhost:9515") // Make sure your WebDriver server is running on this address
        .await
        .expect("Failed to connect to WebDriver");

    // Navigate to a page
    client.goto("http://example.com").await?;

    // At this point, to set custom headers, you might need to utilize browser capabilities
    // or browser extensions as raw header manipulation is not directly supported by WebDriver.
    // One common approach is to use a proxy that adds the headers for you.

    // ... your code to use the headless browser ...

    // Close the browser
    client.close().await
}

Please note the following:

1. WebDriver protocol itself does not have a direct method to modify HTTP request headers for individual requests made by the browser.
2. The common workaround is to use a proxy server that modifies the HTTP requests for you by appending the required headers.
3. The above example demonstrates setting up a headless Chrome session with Fantoccini. However, it does not directly set custom headers due to the limitations of the WebDriver protocol.
4. You may consider using browser extensions or setting up a proxy server with tools like mitmproxy, which allows you to intercept and modify HTTP requests.

If you decide to use a proxy server to add custom headers, you can configure the proxy settings in the goog:chromeOptions like so:

let proxy = serde_json::json!({
    "httpProxy": "your-proxy-address:port",
    "sslProxy": "your-proxy-address:port",
});

let opts = serde_json::json!({
    "args": ["--headless"],
    "extensions": [],
    "proxy": proxy,
});

caps.insert(
    String::from("goog:chromeOptions"),
    serde_json::Value::Object(opts),
);

Make sure you replace "your-proxy-address:port" with your actual proxy server details.

Setting custom headers directly in the browser using WebDriver isn't supported, so consider using the proxy approach if you need to modify headers for your web scraping or automation tasks.