fix: Ensure .env loaded before config init during mcp dev startup (#30)

Author: sealpp

mcp_clickhouse/mcp_env.py

@@ -138,5 +138,17 @@ def _validate_required_vars(self) -> None:
             )
 
 
-# Global instance for easy access
-config = ClickHouseConfig()
+# Global instance placeholder for the singleton pattern
+_CONFIG_INSTANCE = None
+
+
+def get_config():
+    """
+    Gets the singleton instance of ClickHouseConfig.
+    Instantiates it on the first call.
+    """
+    global _CONFIG_INSTANCE
+    if _CONFIG_INSTANCE is None:
+        # Instantiate the config object here, ensuring load_dotenv() has likely run
+        _CONFIG_INSTANCE = ClickHouseConfig()
+    return _CONFIG_INSTANCE

mcp_clickhouse/mcp_server.py

@@ -8,7 +8,7 @@
 from dotenv import load_dotenv
 from mcp.server.fastmcp import FastMCP
 
-from mcp_clickhouse.mcp_env import config
+from mcp_clickhouse.mcp_env import get_config
 
 MCP_SERVER_NAME = "mcp-clickhouse"
 
@@ -161,7 +161,7 @@ def run_select_query(query: str):
 
 
 def create_clickhouse_client():
-    client_config = config.get_client_config()
+    client_config = get_config().get_client_config()
     logger.info(
         f"Creating ClickHouse client connection to {client_config['host']}:{client_config['port']} "
         f"as {client_config['username']} "