Ethers Middleware

Ethers uses a middleware-based architecture. You start the middleware stack with a Provider, and wrap it with additional middleware functionalities that you need.

Available Middleware

• Signer: Signs transactions locally, with a private key or a hardware wallet
• Nonce Manager: Manages nonces locally, allowing the rapid broadcast of transactions without having to wait for them to be submitted
• Gas Escalator: Bumps transaction gas prices in the background
• Gas Oracle: Allows getting your gas price estimates from places other than eth_gasPrice.
• Transformer: Allows intercepting and transforming a transaction to be broadcasted via a proxy wallet, e.g. DSProxy.

Example of a middleware stack

use ethers::{
providers::{Provider, Http},
signers::{LocalWallet, Signer},
middleware::{
gas_escalator::{GasEscalatorMiddleware, GeometricGasPrice, Frequency},
gas_oracle::{GasOracleMiddleware, GasNow, GasCategory},
signer::SignerMiddleware,
nonce_manager::NonceManagerMiddleware,
},
core::rand,
};
use std::convert::TryFrom;

// Start the stack
let provider = Provider::<Http>::try_from("http://localhost:8545").unwrap();

// Escalate gas prices
let escalator = GeometricGasPrice::new(1.125, 60u64, None::<u64>);
let provider =
GasEscalatorMiddleware::new(provider, escalator, Frequency::PerBlock);

// Sign transactions with a private key
let signer = LocalWallet::new(&mut rand::thread_rng());
let address = signer.address();
let provider = SignerMiddleware::new(provider, signer);

// Use GasNow as the gas oracle
let gas_oracle = GasNow::new().category(GasCategory::SafeLow);
let provider = GasOracleMiddleware::new(provider, gas_oracle);

// Manage nonces locally
let provider = NonceManagerMiddleware::new(provider, address);

// ... do something with the provider