from django.conf import settings
from web3 import HTTPProvider, Web3
from web3.middleware import geth_poa_middleware
from .utils import Singleton
class Web3Service(metaclass=Singleton):
"""Creates a `web3` instance based on the given Provider."""
def __init__(self, *args, **kwargs):
"""Initializes the `web3` object.
Args:
rpc_provider (HTTPProvider): Valid `web3` HTTPProvider instance (optional)
"""
rpc_provider = kwargs.pop('rpc_provider', None)
if not rpc_provider:
timeout = getattr(settings, "ETHEREUM_NODE_TIMEOUT", 10)
uri = settings.ETHEREUM_NODE_URI
rpc_provider = HTTPProvider(
endpoint_uri=uri,
request_kwargs={
"timeout": timeout
}
)
self.web3 = Web3(rpc_provider)
# If running in a network with PoA consensus, inject the middleware
if getattr(settings, "ETHEREUM_GETH_POA", False):
self.web3.middleware_onion.inject(geth_poa_middleware, layer=0)
super(Web3Service, self).__init__()
