from flask import Flask, request, jsonify

from flask_cors import CORS

import mysql.connector

from mysql.connector import Error

import redis

import json

app = Flask(__name__)

CORS(app)

# =========================

# REDIS CONFIG

# =========================

redis_client = redis.Redis(

host='veera-6nsjc1.serverless.use1.cache.amazonaws.com',

port=6379,

ssl=True,

decode_responses=True,

socket_timeout=5

)

CACHE_TTL = 90

# =========================

# RDS CONFIG (DEV ONLY)

# =========================

db_write_config = {

'host': 'database-1.c8lweogi44to.us-east-1.rds.amazonaws.com',

'user': 'admin',

'password': 'cloud123',

'database': 'dev'

}

db_read_config = {

'host': 'reader.c8lweogi44to.us-east-1.rds.amazonaws.com',

'user': 'admin',

'password': 'cloud123',

'database': 'dev'

}

# =========================

# CONNECTION HELPERS

# =========================

def get_write_connection():

print("✍️ CONNECTING TO RDS WRITER")

return mysql.connector.connect(**db_write_config)

def get_read_connection():

print("👀 CONNECTING TO RDS READER")

return mysql.connector.connect(**db_read_config)

def get_db_info(cursor):

cursor.execute("SELECT @@hostname AS host, @@read_only AS read_only")

return cursor.fetchone()

# =========================

# ROUTES

# =========================

@app.route('/')

def index():

return "API running with Redis + RDS (Reader/Writer)"

# =========================

# READ APIs

# =========================

@app.route('/users', methods=['GET'])

def get_users():

cache_key = "users:all"

try:

# 1️⃣ Redis check

cached_data = redis_client.get(cache_key)

if cached_data:

print("⚡ REDIS CACHE HIT → /users")

return jsonify({

"data": json.loads(cached_data),

"source": "REDIS_CACHE",

"db_role": "READER"

})

print("❌ REDIS CACHE MISS → /users")

# 2️⃣ RDS Reader

conn = get_read_connection()

cursor = conn.cursor(dictionary=True)

cursor.execute("SELECT * FROM users")

users = cursor.fetchall()

db_info = get_db_info(cursor)

print(f"📖 READ FROM RDS READER → host={db_info['host']}")

# 3️⃣ Cache result

redis_client.setex(cache_key, CACHE_TTL, json.dumps(users))

print("📦 DATA STORED IN REDIS CACHE")

return jsonify({

"data": users,

"served_by": db_info["host"],

"read_only": db_info["read_only"],

"db_role": "READER",

"source": "RDS_READER"

})

except Error as err:

print("❌ ERROR:", err)

return jsonify({'error': str(err)}), 500

finally:

if 'cursor' in locals():

cursor.close()

if 'conn' in locals():

conn.close()

@app.route('/users/<int:user_id>', methods=['GET'])

def get_user(user_id):

cache_key = f"user:{user_id}"

try:

cached_data = redis_client.get(cache_key)

if cached_data:

print(f"⚡ REDIS CACHE HIT → /users/{user_id}")

return jsonify({

"data": json.loads(cached_data),

"source": "REDIS_CACHE",

"db_role": "READER"

})

print(f"❌ REDIS CACHE MISS → /users/{user_id}")

conn = get_read_connection()

cursor = conn.cursor(dictionary=True)

cursor.execute("SELECT * FROM users WHERE id = %s", (user_id,))

user = cursor.fetchone()

if not user:

print("⚠️ USER NOT FOUND IN DB")

return jsonify({'error': 'User not found'}), 404

db_info = get_db_info(cursor)

print(f"📖 READ FROM RDS READER → host={db_info['host']}")

redis_client.setex(cache_key, CACHE_TTL, json.dumps(user))

print("📦 USER STORED IN REDIS CACHE")

return jsonify({

"data": user,

"served_by": db_info["host"],

"read_only": db_info["read_only"],

"db_role": "READER",

"source": "RDS_READER"

})

except Error as err:

print("❌ ERROR:", err)

return jsonify({'error': str(err)}), 500

finally:

if 'cursor' in locals():

cursor.close()

if 'conn' in locals():

conn.close()

# =========================

# WRITE APIs

# =========================

@app.route('/users/add', methods=['POST'])

def add_user():

try:

print("✍️ WRITE REQUEST → /users/add")

conn = get_write_connection()

cursor = conn.cursor()

data = request.json

cursor.execute(

"INSERT INTO users (name, email) VALUES (%s, %s)",

(data['name'], data['email'])

)

conn.commit()

print("✅ WRITE SUCCESSFUL ON RDS WRITER")

# Cache invalidation

redis_client.delete("users:all")

print("🧹 CACHE INVALIDATED → users:all")

return jsonify({'message': 'User added successfully'}), 201

except Error as err:

print("❌ WRITE ERROR:", err)

return jsonify({'error': str(err)}), 500

finally:

cursor.close()

conn.close()

@app.route('/users/update/<int:user_id>', methods=['PUT'])

def update_user(user_id):

try:

print(f"✍️ WRITE REQUEST → /users/update/{user_id}")

conn = get_write_connection()

cursor = conn.cursor()

data = request.json

cursor.execute(

"UPDATE users SET name = %s, email = %s WHERE id = %s",

(data['name'], data['email'], user_id)

)

conn.commit()

print("✅ UPDATE SUCCESSFUL ON RDS WRITER")

redis_client.delete("users:all")

redis_client.delete(f"user:{user_id}")

print("🧹 CACHE INVALIDATED → users:all, user:{user_id}")

return jsonify({'message': 'User updated successfully'})

except Error as err:

print("❌ UPDATE ERROR:", err)

return jsonify({'error': str(err)}), 500

finally:

cursor.close()

conn.close()

@app.route('/users/delete/<int:user_id>', methods=['DELETE'])

def delete_user(user_id):

try:

print(f"✍️ WRITE REQUEST → /users/delete/{user_id}")

conn = get_write_connection()

cursor = conn.cursor()

cursor.execute("DELETE FROM users WHERE id = %s", (user_id,))

conn.commit()

print("✅ DELETE SUCCESSFUL ON RDS WRITER")

redis_client.delete("users:all")

redis_client.delete(f"user:{user_id}")

print("🧹 CACHE INVALIDATED → users:all, user:{user_id}")

return jsonify({'message': 'User deleted successfully'})

except Error as err:

print("❌ DELETE ERROR:", err)

return jsonify({'error': str(err)}), 500

finally:

cursor.close()

conn.close()

# =========================

# ENTRY POINT

# =========================

if __name__ == '__main__':

print("🚀 Starting Flask API with Redis + RDS")

app.run(host='0.0.0.0', port=5000, debug=True)