Read base fee from Geth

base_fee.py

import requests

FILE_NAME = "base_fee.csv"
LONDON_FORK_BLOCK = 12_965_000

session = requests.Session()
headers = {"Content-type": "application/json"}

# Get latest block number from Geth
response = session.post(
    "http://localhost:8545",
    json={"jsonrpc": "2.0", "method": "eth_blockNumber", "params": [], "id": 1},
    headers=headers,
)
end_block = int(response.json()["result"], 16) + 1

# Get latest block number in output
rw_mode = "a"
try:
    lines = open(FILE_NAME, "r").readlines()
    start_block = int(lines[-1].split(",")[0]) + 1
except (OSError, IndexError):
    rw_mode = "w"
    start_block = LONDON_FORK_BLOCK

# Get the base fee for the desired blocks, and write to file
params = [None, False]
payload = {"jsonrpc": "2.0", "method": "eth_getBlockByNumber", "params": params, "id": 1}

print(f"Reading blocks in the range [{start_block}, {end_block})")

with open(FILE_NAME, rw_mode) as o:
    for b in range(start_block, end_block):
        # Print progress every hundred blocks
        if b % 100 == 0:
            print(b, end="\r")

        params[0] = f"0x{b:x}"

        response = session.post("http://localhost:8545", json=payload, headers=headers)
        base_fee = int(response.json()["result"]["baseFeePerGas"], 16)

        o.write(f"{b},{base_fee}\n")

    print("Done!")