Python Redis

This is a simple implementation of a Redis clone written in Python. It is not meant to be a fully-featured Redis server, but rather a demonstration of how the Redis protocol works.

Features

The following Redis commands are implemented:

• PING: Sends a PONG response to the client.
• ECHO: Echoes back the provided argument to the client.
• SET: Sets a key-value pair in the database. Optionally takes a px argument to set an expiry time in milliseconds.
• GET: Gets the value of a key from the database. If the key has an expiry time set and it has passed, the key-value pair is deleted and -1 is returned to the client.

Running the Server

To run the server, simply execute the following command (it requires Python 3):

./redis-clone

The server will listen on localhost:6379 for incoming connections.

Connecting to the Server

You can use any Redis client to connect to the server. For example, to connect to the server using redis-cli, run the following command:

redis-cli -h localhost -p 6379

You should then see a 127.0.0.1:6379> prompt, where you can enter Redis commands as you would with a regular Redis server.

Limitations

This Redis clone has several limitations compared to a real Redis server:

• Only a limited set of commands are implemented.
• The database is not persisted to disk, so all data is lost when the server is stopped.
• There is no support for multiple databases or authentication.

Common Bug

When running your server locally, you might see an error like this:

Traceback (most recent call last):
  File "/.../python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/.../python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/app/app/main.py", line 11, in <module>
    main()
  File "/app/app/main.py", line 6, in main
    s = socket.create_server(("localhost", 6379), reuse_port=True)
AttributeError: module 'socket' has no attribute 'create_server'

This is because socket.create_server was introduced in Python 3.8, and you might be running an older version.

You can fix this by installing Python 3.8 locally and using that.