Codecrafters Redis

Solving the codecrafters redis challenge in Python.

Instructions

Simply use make to run server.

# starts the your_program.sh script.
make

We use pipenv to initialize our development environment.

# install necessary requirements
pipenv install

If you don't want to use pipenv, simply read the list of requirements present in the Pipfile and make sure those packages are available on your path.

Root Structure

.
├── app # main app directory
├── CODECRAFTERS_README.md
├── codecrafters.yml
├── Makefile
├── Pipfile
├── Pipfile.lock
├── pyproject.toml
├── README.md
├── spawn_replica.sh # run multiple instances of app as 'replicas'
├── tests # tests folder
├── watch.sh # run app as a hot-reload server (requires executable 'entr' in path)
└── your_program.sh # actual script to run app

Of note are the folders,

• app: Actual logic of the app module which is run as our redis server.
• tests: Tests directory that contains unit and integration tests used during development.

App Directory

.
├── args.py # parsing of command line arguments
├── commands # handlers for specific redis commands (eg, handlers/get.py handles command GET)
├── config.py # redis server config
├── context.py # context required for execution of commands
├── info # redis server info and stats
├── __init__.py
├── logger.py # logging config
├── main.py # entrypoint
├── queue.py # wrapper around python queue (used for redis transactions)
├── replication # logic specific to the server running as a replica
├── resp # Redis Serialization Protocol (RESP)
├── storage # in-memory storage and rdb config
└── utils # utils used by the main app

Each sub module within app usually contains some common file patterns as,

• base.py: Contains definitions of base classes and types that are used by other files within the submodule.
• errors.py: Defines errors that are specific to the submodule.
• constants.py: Constants that are declared at a single place to make them reusable.
• parser.py: Parsing logic required by the submodule.

Running Tests

You can use the Makefile to run tests.

# run unit tests
make unit-test

# run integration tests
make integration-test

We use pytest for unit tests, make sure it is installed in your environment.

Contributing

This repo is mostly for self-learning and so I'm not currently accepting any contributions. If you do make a PR, make sure to install pre-commit before making any changes.

# install pre-commit so linting errors are caught before commit
pre-commit install

# you can also run the hooks manually
pre-commit run --all-files