Warning
Gas price strategy is only supported for legacy transactions. The London fork introduced maxFeePerGas and maxPriorityFeePerGas transaction parameters which should be used over gasPrice whenever possible.
For Ethereum (legacy) transactions, gas price is a delicate property. For this reason, Web3 includes an API for configuring it.
The Gas Price API allows you to define Web3's behaviour for populating the gas price. This is done using a "Gas Price Strategy" - a method which takes the Web3 object and a transaction dictionary and returns a gas price (denominated in wei).
To retrieve the gas price using the selected strategy simply call ~web3.eth.Eth.generate_gas_price
>>> web3.eth.generate_gas_price()
20000000000A gas price strategy is implemented as a python method with the following signature:
def gas_price_strategy(web3, transaction_params=None):
...The method must return a positive integer representing the gas price in wei.
To demonstrate, here is a rudimentary example of a gas price strategy that returns a higher gas price when the value of the transaction is higher than 1 Ether.
from web3 import Web3
def value_based_gas_price_strategy(web3, transaction_params):
if transaction_params['value'] > Web3.to_wei(1, 'ether'):
return Web3.to_wei(20, 'gwei')
else:
return Web3.to_wei(5, 'gwei')The gas price strategy can be set by calling ~web3.eth.Eth.set_gas_price_strategy.
from web3 import Web3
def value_based_gas_price_strategy(web3, transaction_params):
...
w3 = Web3(...)
w3.eth.set_gas_price_strategy(value_based_gas_price_strategy)