FastAPI Simple Redis Cache

A simple and easy-to-use caching library for FastAPI that uses Redis as a backend.

Features

• Middleware based caching: Simple middleware extension which will add caching to your API endpoint responses.
• Async support: Fully compatible with FastAPI's async routes.
• Configurable expiration: Set cache TTL (Time-To-Live).
• Lightweight: Minimal dependencies and easy to integrate.

Requirements

• Python (>=3.13,<4.0)
• FastAPI (>=0.116.2,<1.0.0)
• redis-py (>=6.4.0,<7.0.0)

Installation

Install the package using your favorite package manager: PyPi Repo available here

How to Use

Available Parameters

The NaiveCache middleware allows you to set certain parameters

Necessary Parameters

Parameter	Description	Expected Type
redis_host	URL of redis instance to connect to	str
redis_port	Port available to connect at redis_host	str
redis_db	Logical database instance at instance to connect to	int

Optional Parameters

Parameter	Description	Expected Type
redis_username	Username to use when connecting to redis instance	str
redis_password	Password to use when connecting to redis instance	str
redis_prefix	Custom prefix used for all keys before serializing (defaults to undefined-prefix)	str
redis_ttl	Time to live in seconds for entries in database (defaults to 300)	int
excluded_paths	List of strings for paths which should not have their responses cached	[str]

Code Sample

First, you need to initialize the cache and register it with your FastAPI app. This is typically done in your main application file (main.py).

# main.py
import random 

from fastapi import FastAPI
from fastapi_simple_redis_cache.NaiveCache import NaiveCache

app = FastAPI()

app.add_middleware(
    NaiveCache,
    redis_host="my_redis_url",
    redis_port="my_redis_port",
    redis_db=0,
    redis_prefix="my_custom_key_prefix",
    excluded_paths=["/do-not-cache-this-path"]
)

@app.get("/")
def return_cached_value():
    """
    Will be random on first call, then cached response returned on all 
    subsequent calls
    """
    return {"message": random.choice(1,2,3,4)}

@app.get("/do-not-cache-this-path")
def return_cached_value():
    """
    Values will not be cached from this endpoint
    """
    return {"message": random.choice(1,2,3,4)}

Additional Features

Cache-Control

When sending a request to an endpoint, an additional header of cache-control:no-store can be provided which will have the middleware skip the addition of the entry to redis. This feature works regardless of the path being added to the initialized excluded_paths parameter

Response Headers

The NaiveCache middleware adds the following response headers for additional information

Header	Description	Expected Type
x-cache-hit	Boolean indicator if the response from the API was retrieved from cache	(True | False)
x-processing-time	Time in float seconds that it took for the request/response to be generated	float

Misc Notes

This library is a naive implementation of a caching system and is only intended as a primitive implementation for educational usage, it is not recommended to run this in production.

License

This project is licensed under the MIT License.