introduces default RPC endpoint health check utilities, and plant an initial entrypoint at node startup.

nucypher/blockchain/eth/actors.py

@@ -49,7 +49,7 @@ from nucypher.blockchain.eth.registry import ContractRegistry
 from nucypher.blockchain.eth.signers import Signer
 from nucypher.blockchain.eth.trackers import dkg
 from nucypher.blockchain.eth.trackers.bonding import OperatorBondedTracker
-from nucypher.blockchain.eth.utils import truncate_checksum_address
+from nucypher.blockchain.eth.utils import truncate_checksum_address, get_healthy_default_rpc_endpoints
 from nucypher.crypto.powers import (
     CryptoPower,
     RitualisticPower,
@@ -265,6 +265,7 @@ class Operator(BaseActor):
         provider = HTTPProvider(endpoint_uri=uri)
         return provider
 
+
     def connect_condition_providers(
         self, endpoints: Dict[int, List[str]]
     ) -> DefaultDict[int, Set[HTTPProvider]]:
@@ -293,6 +294,13 @@ class Operator(BaseActor):
                     )
                 providers[int(chain_id)].add(provider)
 
+        # Ingest default RPC providers for each chain
+        for chain_id in self.domain.condition_chain_ids:
+            default_endpoints = get_healthy_default_rpc_endpoints(chain_id)
+            for uri in default_endpoints:
+                provider = self._make_condition_provider(uri)
+                providers[chain_id].add(provider)
+
         humanized_chain_ids = ", ".join(
             _CONDITION_CHAINS[chain_id] for chain_id in providers
         )

nucypher/blockchain/eth/clients.py

@@ -10,7 +10,7 @@ from web3.contract.contract import Contract
 from web3.exceptions import TimeExhausted, TransactionNotFound
 from web3.types import TxReceipt, Wei
 
-from nucypher.blockchain.eth.constants import AVERAGE_BLOCK_TIME_IN_SECONDS
+from nucypher.blockchain.eth.constants import AVERAGE_BLOCK_TIME_IN_SECONDS, PUBLIC_CHAINS
 from nucypher.blockchain.middleware.retry import (
     AlchemyRetryRequestMiddleware,
     InfuraRetryRequestMiddleware,

nucypher/blockchain/eth/utils.py

@@ -1,6 +1,8 @@
+from collections import defaultdict
 from decimal import Decimal
-from typing import Union
+from typing import Union, Dict, List
 
+import requests
 from eth_typing import ChecksumAddress
 from web3 import Web3
 from web3.contract.contract import ContractConstructor, ContractFunction
@@ -64,3 +66,36 @@ def get_tx_cost_data(transaction_dict: TxParams):
     max_cost_wei = max_unit_price * transaction_dict["gas"]
     max_cost = Web3.from_wei(max_cost_wei, "ether")
     return max_cost, max_price_gwei, tx_type
+
+
+def rpc_endpoint_health_check(endpoint: str) -> bool:
+    query = {
+        "jsonrpc": "2.0",
+        "method": "eth_getBlockByNumber",
+        "params": ["latest", False],
+        "id": 1
+    }
+    try:
+        response = requests.post(
+            endpoint,
+            json=query,
+            headers={"Content-Type": "application/json"},
+            timeout=5
+        )
+        if response.status_code == 200:
+            data = response.json()
+            if "result" in data and data["result"] is not None:
+                return True
+    except requests.exceptions.RequestException:
+        return False
+
+
+def get_healthy_default_rpc_endpoints(chain_id: int) -> List[str]:
+    healthy = []
+    endpoints = DEFAULT_RPC_ENDPOINTS.get(chain_id)
+    if not endpoints:
+        return healthy
+    for endpoint in endpoints:
+        if rpc_endpoint_health_check(endpoint=endpoint):
+            healthy.append(endpoint)
+    return healthy