Support Ropsten on Infura

web3/auto/infura/__init__.py

@@ -0,0 +1,13 @@
+from web3 import Web3
+from web3.providers.auto import (
+    load_provider_from_uri,
+)
+
+from .endpoints import (
+    INFURA_MAINNET_DOMAIN,
+    build_infura_url,
+)
+
+_infura_url = build_infura_url(INFURA_MAINNET_DOMAIN)
+
+w3 = Web3(load_provider_from_uri(_infura_url))

web3/auto/infura/endpoints.py

@@ -0,0 +1,39 @@
+import logging
+import os
+
+from eth_utils import (
+    ValidationError,
+)
+
+INFURA_MAINNET_DOMAIN = 'mainnet.infura.io'
+INFURA_ROPSTEN_DOMAIN = 'ropsten.infura.io'
+
+WEBSOCKET_SCHEME = 'wss'
+HTTP_SCHEME = 'https'
+
+
+def load_api_key():
+    # at web3py v5, drop old variable name INFURA_API_KEY
+    key = os.environ.get(
+        'WEB3_INFURA_API_KEY',
+        os.environ.get('INFURA_API_KEY', '')
+    )
+    if key == '':
+        logging.getLogger('web3.auto.infura').warning(
+            "No Infura API Key found. Add environment variable WEB3_INFURA_API_KEY to ensure "
+            "continued API access. New keys are available at https://infura.io/register"
+        )
+    return key
+
+
+def build_infura_url(domain):
+    scheme = os.environ.get('WEB3_INFURA_SCHEME', WEBSOCKET_SCHEME)
+
+    if scheme == WEBSOCKET_SCHEME:
+        # websockets doesn't use the API key (yet?)
+        return "%s://%s/ws" % (scheme, domain)
+    elif scheme == HTTP_SCHEME:
+        key = load_api_key()
+        return "%s://%s/%s" % (scheme, domain, key)
+    else:
+        raise ValidationError("Cannot connect to Infura with scheme %r" % scheme)

web3/auto/infura/ropsten.py

@@ -0,0 +1,13 @@
+from web3 import Web3
+from web3.providers.auto import (
+    load_provider_from_uri,
+)
+
+from .endpoints import (
+    INFURA_ROPSTEN_DOMAIN,
+    build_infura_url,
+)
+
+_infura_url = build_infura_url(INFURA_ROPSTEN_DOMAIN)
+
+w3 = Web3(load_provider_from_uri(_infura_url))

web3/providers/auto.py

@@ -21,6 +21,10 @@ def load_provider_from_environment():
     if not uri_string:
         return None
 
+    return load_provider_from_uri(uri_string)
+
+
+def load_provider_from_uri(uri_string):
     uri = urlparse(uri_string)
     if uri.scheme == 'file':
         return IPCProvider(uri.path)