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.
If you are already happily connected to your Ethereum node, then you can skip the rest of the Providers section.
Most nodes have a variety of ways to connect to them. If you have not decided what kind of node to use, head on over to :ref:`choosing_node`
The most common ways to connect to your node are:
- IPC (uses local filesystem: fastest and most secure)
- Websockets (works remotely, faster than HTTP)
- HTTP (more nodes support it)
If you're not sure how to decide, choose this way:
- If you have the option of running Web3.py on the same machine as the node, choose IPC.
- If you must connect to a node on a different computer, use Websockets.
- If your node does not support Websockets, use HTTP.
Most nodes have a way of "turning off" connection options. We recommend turning off all connection options that you are not using. This provides a safer setup: it reduces the number of ways that malicious hackers can try to steal your ether.
Once you have decided how to connect, you specify the details using a Provider. Providers are Web3.py classes that are configured for the kind of connection you want.
See:
- :class:`~web3.providers.ipc.IPCProvider`
- :class:`~web3.providers.websocket.WebsocketProvider`
- :class:`~web3.providers.rpc.HTTPProvider`
Once you have configured your provider, for example:
from web3 import Web3
my_provider = Web3.IPCProvider('/my/node/ipc/path')Then you are ready to initialize your Web3 instance, like so:
w3 = Web3(my_provider)Finally, you are ready to :ref:`get started with Web3.py<first_w3_use>`.
The Web3 object will look for the Ethereum node in a few
standard locations if no providers are specified. Auto-detection happens
when you initialize like so:
from web3.auto import w3
# which is equivalent to:
from web3 import Web3
w3 = Web3()Sometimes, web3 cannot automatically detect where your node is.
- If you are not sure which kind of connection method to use, see :ref:`choosing_provider`.
- If you know the connection method, but not the other information needed to connect (like the path to the IPC file), you will need to look up that information in your node's configuration.
- If you're not sure which node you are using, see :ref:`choosing_node`
For a deeper dive into how automated detection works, see:
Web3 attempts to connect to nodes in the following order, using the first succesful connection it can make:
- The connection specified by an environment variable, see :ref:`provider_uri`
- :class:`~web3.providers.ipc.IPCProvider`, which looks for several IPC file locations
- :class:`~web3.providers.rpc.HTTPProvider`, which attempts to connect to "http://localhost:8545"
- None - if no providers are successful, you can still use Web3 APIs that do not require a connection, like:
Some nodes provide APIs beyond the standards. Sometimes the same information is provided in different ways across nodes. If you want to write code that works across multiple nodes, you may want to look up the node type you are connected to.
For example, the following retrieves the client enode endpoint for both geth and parity:
from web3.auto import w3
connected = w3.isConnected()
if connected and w3.version.node.startswith('Parity'):
enode = w3.parity.enode
elif connected and w3.version.node.startswith('Geth'):
enode = w3.admin.nodeInfo['enode']
else:
enode = NoneAlternatively, you can set the environment variable WEB3_PROVIDER_URI
before starting your script, and web3 will look for that provider first.
Valid formats for the this environment variable are:
file:///path/to/node/rpc-json/file.ipchttp://192.168.1.2:8545https://node.ontheweb.comws://127.0.0.1:8546
There are a couple auto-initialization shortcuts for common providers.
To easily connect to the Infura Mainnet remote node, first register for a free API key if you don't have one at https://infura.io/register .
Then set the environment variable WEB3_INFURA_API_KEY with your API key:
$ export WEB3_INFURA_API_KEY=YourApiKey
If you have checked the box in the Infura UI indicating that requests need
an optional secret key, set the environment variable WEB3_INFURA_API_SECRET:
$ export WEB3_INFURA_API_SECRET=YourSecretKey
>>> from web3.auto.infura import w3
# confirm that the connection succeeded
>>> w3.isConnected()
TrueTo connect to a geth --dev Proof of Authority instance with defaults:
>>> from web3.auto.gethdev import w3
# confirm that the connection succeeded
>>> w3.isConnected()
TrueWeb3 ships with the following providers which are appropriate for connecting to local and remote JSON-RPC servers.
.. py: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.
.. code-block:: python
>>> from web3 import Web3
>>> web3 = Web3(Web3.HTTPProvider("http://127.0.0.1:8545"))
Note that you should create only one HTTPProvider per python
process, as the HTTPProvider recycles underlying TCP/IP network connections,
for better performance.
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.
.. code-block:: python
>>> from web3 import Web3
>>> web3 = Web3(Web3.HTTPProvider("http://127.0.0.1:8545", request_kwargs={'timeout': 60}))
.. py:class:: web3.providers.ipc.IPCProvider(ipc_path=None, testnet=False, timeout=10)
This provider handles interaction with an IPC Socket based JSON-RPC
server.
* ``ipc_path`` is the filesystem path to the IPC socket.:56
.. code-block:: python
>>> from web3 import Web3
>>> web3 = Web3(Web3.IPCProvider("~/Library/Ethereum/geth.ipc"))
If no ``ipc_path`` is specified, it will use the first IPC file
it can find from this list:
- On Linux and FreeBSD:
- ``~/.ethereum/geth.ipc``
- ``~/.local/share/io.parity.ethereum/jsonrpc.ipc``
- On Mac OS:
- ``~/Library/Ethereum/geth.ipc``
- ``~/Library/Application Support/io.parity.ethereum/jsonrpc.ipc``
- On Windows:
- ``\\\.\pipe\geth.ipc``
- ``\\\.\pipe\jsonrpc.ipc``
.. py:class:: web3.providers.websocket.WebsocketProvider(endpoint_uri[, websocket_kwargs])
This provider handles interactions with an WS or WSS based JSON-RPC server.
* ``endpoint_uri`` should be the full URI to the RPC endpoint such as
``'ws://localhost:8546'``.
* ``websocket_kwargs`` this should be a dictionary of keyword arguments which
will be passed onto the ws/wss websocket connection.
.. code-block:: python
>>> from web3 import Web3
>>> web3 = Web3(Web3.WebsocketProvider("ws://127.0.0.1:8546"))
Under the hood, the ``WebsocketProvider`` uses the python websockets library for
making requests. If you would like to modify how requests are made, you can
use the ``websocket_kwargs`` to do so. A common use case for this is increasing
the timeout for each request.
.. code-block:: python
>>> from web3 import Web3
>>> web3 = Web3(Web3.WebsocketProvider("http://127.0.0.1:8546", websocket_kwargs={'timeout': 60}))
.. py:currentmodule:: web3.providers.eth_tester
Warning
Experimental: This provider is experimental. There are still significant gaps in functionality. However, it is the default replacement for :class:`web3.providers.tester.EthereumTesterProvider` and is being actively developed and supported.
.. py:class:: EthereumTesterProvider(eth_tester=None)
This provider integrates with the ``eth-tester`` library. The
``eth_tester`` constructor argument should be an instance of the
:class:`~eth_tester.EthereumTester` class provided by the ``eth-tester``
library. If you would like a custom eth-tester instance to test with,
see the ``eth-tester`` library documentation for details.
.. code-block:: python
>>> from web3 import Web3, EthereumTesterProvider
>>> w3 = Web3(EthereumTesterProvider())
Warning
Deprecated: This provider is deprecated in favor of :class:`~web3.providers.eth_tester.EthereumTesterProvider` and the newly created eth-tester.
.. py:class:: web3.providers.tester.EthereumTesterProvider()
This provider can be used for testing. It uses an ephemeral blockchain
backed by the ``ethereum.tester`` module.
.. code-block:: python
>>> from web3 import Web3
>>> from web3.providers.tester import EthereumTesterProvider
>>> w3 = Web3(EthereumTesterProvider())
Warning
Deprecated: This provider is deprecated in favor of :class:`~web3.providers.eth_tester.EthereumTesterProvider` and the newly created eth-tester.
.. py:class:: 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.
:class:`~web3.providers.auto.AutoProvider` is the default used when initializing :class:`web3.Web3` without any providers. There's rarely a reason to use it explicitly.
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 handle the request, then a
web3.exceptions.UnhandledRequest exception will be thrown.