How to use Redis for rate limiting?

There are several ways to use Redis for rate limiting, but one common approach is to use Redis’ built-in data structures and commands to keep track of the number of requests made by a user or IP address over a certain time period.

One way to implement rate limiting is to use Redis’ INCR command to increment a counter for a user or IP address each time a request is made. Then, you can use the EXPIRE command to set a time-to-live (TTL) for the counter, after which the counter will automatically be deleted. To check if a user or IP has exceeded the rate limit, you can check the value of the counter with the GET command.

Here’s an example of how you might implement rate limiting using Redis commands in Python:

import redis

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

def is_rate_limited(user_id):
    key = f"rate_limit:{user_id}"
    # Increment the counter for the user
    r.incr(key)
    # Set the TTL for the counter to 1 hour
    r.expire(key, 3600)
    # Check if the user has made more than 100 requests in the last hour
    return r.get(key) > 100

if is_rate_limited("user1"):
    print("You have exceeded the rate limit.")
else:
    print("OK")