Implementing Gravatars with Rust is relatively straightforward. Below you’ll find an example of how to do so.
Example Implementation
use sha2::{Digest, Sha256};
fn main() {
let email = String::from("EMAIL_ADDRESS");
let trimmed_email = email.trim();
let mut hashed_email = Sha256::new();
hashed_email.update(trimmed_email);
println!("https://gravatar.com/avatar/{:X}", hashed_email.finalize());
}
Gravatar Developer Docs 