Providers¶

The provider is how web3 talks to the blockchain. Providers take JSON-RPC requests and return the response. This is normally done by submitting the request to an HTTP or IPC socket based server.

The Web3 object requires at least one provider to be able to function.

>>> from web3 import Web3, HTTPProvider
>>> provider = HTTPProvider('http://localhost:8545')
>>> web3 = Web3(provider)

Built In Providers¶

Web3 ships with the following providers which are appropriate for connecting to local and remote JSON-RPC servers.

HTTPProvider¶

class web3.providers.rpc.HTTPProvider(endpoint_uri[, request_kwargs])¶

This provider handles interactions with an HTTP or HTTPS based JSON-RPC server.

endpoint_uri should be the full URI to the RPC endpoint such as 'https://localhost:8545'. For RPC servers behind HTTP connections running on port 80 and HTTPS connections running on port 443 the port can be omitted from the URI.
request_kwargs this should be a dictionary of keyword arguments which will be passed onto the http/https request.

>>> from web3 import Web3
>>> web3 = Web3(Web3.HTTPProvider("http://127.0.0.1:8545")

Under the hood, the HTTPProvider uses the python requests library for making requests. If you would like to modify how requests are made, you can use the request_kwargs to do so. A common use case for this is increasing the timeout for each request.

>>> from web3 import Web3
>>> web3 = Web3(Web3.HTTPProvider("http://127.0.0.1:8545", request_kwargs={'timeout': 60})

IPCProvider¶

IPCProvider(ipc_path=None, testnet=False):

This provider handles interaction with an IPC Socket based JSON-RPC server.

ipc_path is the filesystem path to the IPC socket.:56

>>> from web3 import Web3
>>> web3 = Web3(Web3.IPCProvider("~/Library/Ethereum/geth.ipc")

EthereumTesterProvider¶

Warning

Experimental: This provider is experimental and should be used with caution.

class web3.providers.eth_tester.EthereumTesterProvider(eth_tester)¶

This provider integrates with the ethereum-tester library. The eth_tester constructor argument should be an instance of the eth_tester.EthereumTester class provided by the ethereum-tester library. See the ethereum-tester library documentation for instructions on how to use the library.

>>> from web3 import Web3
>>> from web3.providers.eth_tester import EthereumTesterProvider
>>> from eth_tester import EthereumTester
>>> eth_tester = EthereumTester()
>>> web3 = Web3(EthereumTesterProvider(eth_tester))

EthereumTesterProvider (legacy)¶

Warning

Pending Deprecation: This provider is being deprecated soon in favor of the newly created ethereum-tester library.

EthereumTesterProvider():: This provider can be used for testing. It uses an ephemeral blockchain backed by the ethereum.tester module.

TestRPCProvider¶

Warning

Pending Deprecation: This provider is being deprecated soon in favor of the newly created ethereum-tester library.

TestRPCProvider():: This provider can be used for testing. It uses an ephemeral blockchain backed by the ethereum.tester module. This provider will be slower than the EthereumTesterProvider since it uses an HTTP server for RPC interactions with.

Using Multiple Providers¶

Web3 supports the use of multiple providers. This is useful for cases where you wish to delegate requests across different providers. To use this feature, simply instantiate your web3 instance with an iterable of provider instances.

>>> from web3 import Web3, HTTPProvider
>>> from . import MySpecialProvider
>>> special_provider = MySpecialProvider()
>>> infura_provider = HTTPProvider('https://ropsten.infura.io')
>>> web3 = Web3([special_provider, infura_provider])

When web3 has multiple providers it will iterate over them in order, trying the RPC request and returning the first response it receives. Any provider which cannot respond to a request must throw a web3.exceptions.CannotHandleRequest exception.

If none of the configured providers are able to hand the request, then a web3.exceptions.UnhandledRequest exception will be thrown.