How to Use Redis With Python

Table of Contents

In this tutorial, you’ll learn how to use Python with Redis (pronounced RED-iss, or maybe REE-diss or Red-DEES, depending on who you ask), which is a lightning fast in-memory key-value store that can be used for anything from A to Z. Here’s what Seven Databases in Seven Weeks, a popular book on databases, has to say about Redis:

It’s not simply easy to use; it’s a joy. If an API is UX for programmers, then Redis should be in the Museum of Modern Art alongside the Mac Cube.

…

And when it comes to speed, Redis is hard to beat. Reads are fast, and writes are even faster, handling upwards of 100,000 SET operations per second by some benchmarks. (Source)

Intrigued? This tutorial is built for the Python programmer who may have zero to little Redis experience. We’ll tackle two tools at once and introduce both Redis itself as well as one of its Python client libraries, redis-py.

redis-py (which you import as just redis) is one of many Python clients for Redis, but it has the distinction of being billed as “currently the way to go for Python” by the Redis developers themselves. It lets you call Redis commands from Python, and get back familiar Python objects in return.

In this tutorial, you’ll cover:

Installing Redis from source and understanding the purpose of the resulting binaries
Learning a bite-size slice of Redis itself, including its syntax, protocol, and design
Mastering redis-py while also seeing glimpses of how it implements Redis’ protocol
Setting up and communicating with an Amazon ElastiCache Redis server instance

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Installing Redis From Source

As my great-great-grandfather said, nothing builds grit like installing from source. This section will walk you through downloading, making, and installing Redis. I promise that this won’t hurt one bit!

Note: This section is oriented towards installation on Mac OS X or Linux. If you’re using Windows, there is a Microsoft fork of Redis that can be installed as a Windows Service. Suffice it to say that Redis as a program lives most comfortably on a Linux box and that setup and use on Windows may be finicky.

First, download the Redis source code as a tarball:

$ redisurl="http://download.redis.io/redis-stable.tar.gz"
$ curl -s -o redis-stable.tar.gz $redisurl

Next, switch over to root and extract the archive’s source code to /usr/local/lib/:

$ sudo su root
$ mkdir -p /usr/local/lib/
$ chmod a+w /usr/local/lib/
$ tar -C /usr/local/lib/ -xzf redis-stable.tar.gz

Optionally, you can now remove the archive itself:

$ rm redis-stable.tar.gz

This will leave you with a source code repository at /usr/local/lib/redis-stable/. Redis is written in C, so you’ll need to compile, link, and install with the make utility:

$ cd /usr/local/lib/redis-stable/
$ make && make install

Using make install does two actions:

The first make command compiles and links the source code.
The make install part takes the binaries and copies them to /usr/local/bin/ so that you can run them from anywhere (assuming that /usr/local/bin/ is in PATH).

Here are all the steps so far:

$ redisurl="http://download.redis.io/redis-stable.tar.gz"
$ curl -s -o redis-stable.tar.gz $redisurl
$ sudo su root
$ mkdir -p /usr/local/lib/
$ chmod a+w /usr/local/lib/
$ tar -C /usr/local/lib/ -xzf redis-stable.tar.gz
$ rm redis-stable.tar.gz
$ cd /usr/local/lib/redis-stable/
$ make && make install

At this point, take a moment to confirm that Redis is in your PATH and check its version:

$ redis-cli --version
redis-cli 5.0.3

If your shell can’t find redis-cli, check to make sure that /usr/local/bin/ is on your PATH environment variable, and add it if not.

In addition to redis-cli, make install actually leads to a handful of different executable files (and one symlink) being placed at /usr/local/bin/:

$ # A snapshot of executables that come bundled with Redis
$ ls -hFG /usr/local/bin/redis-* | sort
/usr/local/bin/redis-benchmark*
/usr/local/bin/redis-check-aof*
/usr/local/bin/redis-check-rdb*
/usr/local/bin/redis-cli*
/usr/local/bin/redis-sentinel@
/usr/local/bin/redis-server*

While all of these have some intended use, the two you’ll probably care about most are redis-cli and redis-server, which we’ll outline shortly. But before we get to that, setting up some baseline configuration is in order.

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Configuring Redis

Redis is highly configurable. While it runs fine out of the box, let’s take a minute to set some bare-bones configuration options that relate to database persistence and basic security: