EIP-1559 gas price / fee history oracles

[wolovim]

Pre-London (legacy) transactions rely on a gasPrice to be set by the user or determined by Web3.py or the client. Post-London transactions drop gasPrice in favor of maxFeePerGas and maxPriorityFeePerGas.

Questions:

• Will eth_gasPrice continue to be supported for legacy transactions as is?
  • Geth will continue to return total fees paid (tip + base)
• Should Web3.py continue to offer gas price strategies for legacy transactions? Support both legacy and new transactions? Just new txs?
  • TBD
• Should a new oracle fee API return both a maxFeePerGas and a maxPriorityFeePerGas, or just the latter?
  • New RPC method, eth_maxPriorityFeePerGas available after London. Effectively returns eth_gasPrice - baseFee. Geth shoots for 60th percentile as the price suggestion to keep downward pressure on the price.
• What are optimal defaults for maxFeePerGas and maxPriorityFeePerGas if we don't just let the client decide? Or should that be the responsibility of the client?
  • Geth: "If the user doesn't specify maxFeePerGas, we default to maxPriorityFeePerGas + 2*baseFee"

Resources:

• Peter's description of Geth's gas oracle behavior
• Freshly merged Geth feeHistory PR and context
• Newest ethers.js release with 1559 support

Things that may update in Web3.py:

• generate_gas_price API
• gas_strategies
• gas_price_strategy middleware
• gas_price.rst docs pages
• new APIs for maxFeePerGas and/or maxPriorityFeePerGas

[banteg]

I added eth_maxPriorityFeePerGas in #2100. Tested with devel version of Erigon.

[L-F-Escobar]

beautiful