up

docker-compose.yml

@@ -28,8 +28,10 @@ services:
         condition: service_healthy
     volumes:
       - ./data.csv:/app/data.csv
+      - shared_data:/shared
     networks:
       - mynetwork
+    restart: "no"
 
   web:
     build: ./web
@@ -43,10 +45,15 @@ services:
       db:
         condition: service_healthy
       filler:
-        condition: service_completed_successfully
+        condition: service_started
     networks:
       - mynetwork
+    volumes:
+      - shared_data:/shared
 
 networks:
   mynetwork:
     driver: bridge
+
+volumes:
+  shared_data:

filler/filler_db.py

@@ -50,3 +50,8 @@ with connection.cursor() as cursor:
     cursor.execute("SELECT * FROM data")
     for row in cursor.fetchall():
         logger.info(f"Data: {row}")
+
+with open('/app/data_filled.signal', 'w') as signal_file:
+    signal_file.write('done')
+
+logger.info("Filler task completed. Signal file created.")

web/app.py

@@ -1,29 +1,70 @@
+# ./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():
-    return pymysql.connect(
+    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()
-    return jsonify(result)
+            logger.info("Data queried successfully.")
+    else:
+        logger.error("Failed to fetch data due to database connection error.")
+        return jsonify({"error": "Database connection failed"}), 500
 
-@app.route('/health')
+    return jsonify(result), 200
-def health():
-    return jsonify({"status": "OK"})
 
 @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)