Replace hardcoded values with environment variables in Bot and attendee directories

[Copilot]

Hardcoded URLs, ports, API keys, and service endpoints across the Bot/ and attendee/ directories prevented flexible deployment and posed security risks.

Changes

Bot Directory

• Created Bot/app/core/config.py - Centralized configuration module with error-handling for type conversions
• Replaced hardcoded values in:
  • Redis connection parameters (host='redis', port=6379, db=0)
  • Server binding (host="0.0.0.0", port=8001)
  • API endpoints (Lingo callback URL, join meeting URL, schedule URL)
  • OAuth credentials and webhook addresses
• Updated Bot/env.sample with 22 environment variables

Attendee Directory

• Replaced hardcoded Lingo callback URL in bot_controller.py:

  # Before
  url = "http://lingo-bot:8001/meetings/call-to-lingo"
  
  # After
  url = os.environ.get("LINGO_CALLBACK_URL", "http://lingo-bot:8001/meetings/call-to-lingo")

• Updated attendee/env.sample with LINGO_CALLBACK_URL

Configuration Pattern

All numeric environment variables include try-except blocks to prevent ValueError on invalid input:

try:
    REDIS_PORT = int(os.getenv("REDIS_PORT", "6379"))
except (ValueError, TypeError):
    REDIS_PORT = 6379

New Environment Variables

• Infrastructure: REDIS_HOST, REDIS_PORT, REDIS_DB, BOT_SERVER_HOST, BOT_SERVER_PORT
• API endpoints: JOIN_MEETING_URL, SCHEDULE_JOIN_BOT_URL, GET_MEETING_URL, LINGO_CALLBACK_URL, LINGO_SAVE_TRANSCRIPTION_URL
• Auth/Webhook: CLIENT_ID, CLIENT_SECRET, TOKEN_URI, WEBHOOK_ADDR, USER_ID

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add Environment Variables Instead of Hardcoded Values</issue_title>
<issue_description>- Review the bot/ and attendee/ directories.

• Identify and remove all hardcoded values (e.g., URLs, API keys, bucket names, ports, etc.).
• Replace them with environment variables for better configurability and security.
• Update .env.example and related documentation accordingly.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add Environment Variables Instead of Hardcoded Values #8

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