Fix: Switch to full python image and add network wait loop to solve DNS race conditions

Dockerfile

@@ -1,11 +1,12 @@
-FROM python:3.9-slim
+FROM python:3.9
 
 # Set working directory
 WORKDIR /app
 
-# Install system dependencies
+# Install system dependencies (including ca-certificates explicitly)
 RUN apt-get update && apt-get install -y --no-install-recommends \
     gcc \
+    ca-certificates \
     && rm -rf /var/lib/apt/lists/*
 
 # Copy requirements

bot.py

@@ -2,6 +2,8 @@ import os
 import json
 import asyncio
 import logging
+import socket
+import time
 from io import BytesIO
 from dotenv import load_dotenv
 from telegram import Update
@@ -380,11 +382,32 @@ async def help_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
     await update.message.reply_text(help_message)
 
 
+def wait_for_network():
+    """Wait for network connectivity/DNS resolution before starting."""
+    logger.info("Checking network connectivity...")
+    retries = 0
+    max_retries = 12  # Wait up to 60 seconds
+    while retries < max_retries:
+        try:
+            socket.gethostbyname("api.telegram.org")
+            logger.info("Network is ready! DNS resolution successful.")
+            return
+        except socket.gaierror:
+            retries += 1
+            logger.warning(f"DNS resolution failed for api.telegram.org. Retrying in 5 seconds... ({retries}/{max_retries})")
+            time.sleep(5)
+    logger.error("Could not resolve api.telegram.org after multiple attempts. Exiting.")
+    # We continue anyway, let the library fail if it must, but we warned the logs.
+
+
 def main():
     """Start the bot."""
     if not TELEGRAM_BOT_TOKEN:
         raise ValueError("TELEGRAM_BOT_TOKEN environment variable is not set!")
     
+    # Wait for network to be ready
+    wait_for_network()
+    
     # Configure connection options to be more resilient
     request = HTTPXRequest(
         connection_pool_size=8,