hwdocker/web/app.py

# ./web/app.py

from flask import Flask, jsonify
import pymysql
import os
import logging
import time

app = Flask(__name__)

# Configure logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

def get_db_connection():
    try:
        connection = pymysql.connect(
            host='db',
            user=os.getenv('MYSQL_USER'),
            password=os.getenv('MYSQL_PASSWORD'),
            db=os.getenv('MYSQL_DATABASE')
        )
        logger.info("Connected to the database.")
        return connection
    except pymysql.MySQLError as e:
        logger.error(f"Database connection failed: {e}")
        return None

def wait_for_file(file_path):
    logger.info(f"Waiting for the file: {file_path} to exist...")
    while not os.path.isfile(file_path):
        logger.debug("File not found, sleeping for 1 second...")
        time.sleep(1)
    logger.info("Signal file detected, proceeding...")

@app.route('/health')
def health():
    # Check if the application can connect to the database
    conn = get_db_connection()
    if conn:
        logger.info("Application is healthy.")
        return jsonify({"status": "OK"}), 200
    else:
        logger.warning("Application health check failed.")
        return jsonify({"status": "FAIL"}), 500

@app.route('/')
def index():
    conn = get_db_connection()
    if conn:
        with conn.cursor() as cursor:
            cursor.execute("SELECT name, age FROM data")
            result = cursor.fetchall()
            logger.info("Data queried successfully.")
    else:
        logger.error("Failed to fetch data due to database connection error.")
        return jsonify({"error": "Database connection failed"}), 500

    return jsonify(result), 200

@app.errorhandler(404)
def not_found(e):
    logger.warning("404 error encountered.")
    return jsonify({"error": "Not found"}), 404

if __name__ == "__main__":
    signal_file_path = "/shared/data_filled.signal"
    wait_for_file(signal_file_path)

    app.run(host='0.0.0.0', port=8000)