Repository: aptos-labs/aptos-core
File: keyless/pepper/service/src/main.rs (Rust)

Code before:
    pepper_service_port: u16,

    /// The hex-encoded VUF private key (used directly if provided, otherwise derived from the seed)
    #[arg(
        long,
        required_unless_present = "vuf_private_key_seed_hex",
        conflicts_with = "vuf_private_key_seed_hex"
    )]
    vuf_private_key_hex: Option<String>,

    /// The hex-encoded VUF private key seed (used to derive the private key if the key is not provided directly)
    #[arg(
        long,
        required_unless_present = "vuf_private_key_hex",
        conflicts_with = "vuf_private_key_hex"
    )]
    vuf_private_key_seed_hex: Option<String>,

    #[arg(long)]
    jwk_issuers_override: Vec<JWKIssuer>,
}

#[tokio::main]
async fn main() {
    // Fetch the command line arguments
    let args = Args::parse();

    // Start the logger
    aptos_logger::Logger::new().init();
    info!("Starting the Pepper service...");

    // Start the metrics server
    start_metrics_server();

    // Fetch the VUF public and private keypair (this will load the private key into memory)
    info!("Fetching the VUF public and private keypair for the pepper service...");
    let (vuf_public_key, vuf_private_key) = vuf_pub_key::get_pepper_service_vuf_keypair(
        args.vuf_private_key_hex,
        args.vuf_private_key_seed_hex,
    );
    info!("Retrieved the VUF public key: {:?}", vuf_public_key);

    // Collect the account recovery managers
    info!("Collecting the account recovery managers...");
    let account_recovery_managers =
        Arc::new(AccountRecoveryManagers::new(args.account_recovery_managers));

    // Start the cached resource fetcher
    let cached_resources = resource_fetcher::start_cached_resource_fetcher(
        args.on_chain_groth16_vk_url,
        args.on_chain_keyless_config_url,

Review comment (suggestion):
Can you add a comment similar to what we do for `account_recovery_managers` for how this can be used? e.g.,

```
    /// A list of account recovery managers that are allowed to override the
    /// aud claim in the JWTs they issue when handling pepper requests.
    ///
    /// For example:
    /// --account-recovery-managers="https://accounts.google.com 1234567890"
    /// --account-recovery-managers="https://accounts.facebook.com 9876543210"
```

The comment will be displayed in the `--help` command 😄 

Code after:
    pepper_service_port: u16,

    /// The hex-encoded VUF private key (used directly if provided, otherwise derived from the seed)
    #[arg(
        long,
        required_unless_present = "vuf_private_key_seed_hex",
        conflicts_with = "vuf_private_key_seed_hex"
    )]
    vuf_private_key_hex: Option<String>,

    /// The hex-encoded VUF private key seed (used to derive the private key if the key is not provided directly)
    #[arg(
        long,
        required_unless_present = "vuf_private_key_hex",
        conflicts_with = "vuf_private_key_hex"
    )]
    vuf_private_key_seed_hex: Option<String>,

    /// A list of JWK URLs the pepper service should monitor in addition to the default issuers.
    /// This can also be used to override the JWK URL of default issuers.
    ///
    /// For example:
    /// --jwk-issuers-override="https://accounts.google.com https://www.googleapis.com/oauth2/v999/certs"
    /// --jwk-issuers-override="https://www.facebook.com https://www.facebook.com/.well-known/oauth/openid/jwks"
    #[arg(long)]
    jwk_issuers_override: Vec<JWKIssuer>,
}

#[tokio::main]
async fn main() {
    // Fetch the command line arguments
    let args = Args::parse();

    // Start the logger
    aptos_logger::Logger::new().init();
    info!("Starting the Pepper service...");

    // Start the metrics server
    start_metrics_server();

    // Fetch the VUF public and private keypair (this will load the private key into memory)
    info!("Fetching the VUF public and private keypair for the pepper service...");
    let (vuf_public_key, vuf_private_key) = vuf_pub_key::get_pepper_service_vuf_keypair(
        args.vuf_private_key_hex,
        args.vuf_private_key_seed_hex,
    );
    info!("Retrieved the VUF public key: {:?}", vuf_public_key);

    // Collect the account recovery managers
    info!("Collecting the account recovery managers...");
    let account_recovery_managers =