Redis as message broker in Flask - Mini Project: Build & Apply

Redis as message broker with Flask

📖 Scenario: You are building a simple Flask web app that uses Redis as a message broker to send and receive messages asynchronously.This is useful in real-world apps where you want to decouple parts of your system, like sending notifications or processing tasks in the background.

🎯 Goal: Build a Flask app that publishes messages to a Redis channel and subscribes to that channel to receive messages.You will create the Redis connection, configure the channel name, publish messages, and subscribe to messages using Redis Pub/Sub.

📋 What You'll Learn

Use the redis Python package to connect to Redis

Create a Redis client instance

Define a channel name as a configuration variable

Publish messages to the Redis channel

Subscribe and listen to messages from the Redis channel

💡 Why This Matters

🌍 Real World

Redis is often used as a fast message broker to enable communication between different parts of an application or between different services.

💼 Career

Understanding how to use Redis Pub/Sub with Flask is useful for backend developers building scalable, decoupled web applications and microservices.

1

Create Redis client connection

Import the redis package and create a Redis client instance called redis_client connecting to localhost on the default port.

Flask

# Your code here

Need a hint?

Use redis.Redis() with host='localhost', port=6379, and db=0.

2

Define Redis channel name

Create a variable called channel_name and set it to the string 'flask_channel' to use as the Redis Pub/Sub channel.

Flask

import redis

redis_client = redis.Redis(host='localhost', port=6379, db=0)

# Your code here

Need a hint?

Just assign the string 'flask_channel' to channel_name.

3

Publish a message to the Redis channel

Use the redis_client.publish() method to send the message 'Hello from Flask!' to the channel stored in channel_name.

Flask

import redis

redis_client = redis.Redis(host='localhost', port=6379, db=0)

channel_name = 'flask_channel'

# Your code here

Need a hint?

Call redis_client.publish(channel_name, 'Hello from Flask!') to send the message.

4

Subscribe and listen to messages from the Redis channel

Create a PubSub object from redis_client called pubsub. Use pubsub.subscribe(channel_name) to subscribe. Then write a for loop iterating over pubsub.listen() to print messages when message['type'] == 'message'.

Flask

import redis

redis_client = redis.Redis(host='localhost', port=6379, db=0)

channel_name = 'flask_channel'

redis_client.publish(channel_name, 'Hello from Flask!')

# Your code here

Need a hint?

Use redis_client.pubsub() to create pubsub, subscribe with pubsub.subscribe(channel_name), then loop over pubsub.listen() checking message['type'] == 'message'.