unicorn is an HTTP server for Rack applications designed to only serve fast clients on low-latency, high-bandwidth connections and take advantage of features in Unix/Unix-like kernels.
Slow clients should only be served by placing a reverse proxy capable of fully buffering both the the request and response in between unicorn and slow clients.
This is free and open source software.
- Designed for Rack, Unix, fast clients, and ease-of-debugging.
- Compatible with Ruby 2.0.0 and later.
- Process management: unicorn will reap and restart workers that die from broken apps. There is no need to manage multiple processes or ports yourself. unicorn can spawn and manage any number of worker processes you choose to scale to your backend.
- Load balancing is done entirely by the operating system kernel.
- Requests never pile up behind a busy worker process.
- Does not care if your application is thread-safe or not, workers all run within their own isolated address space and only serve one client at a time for maximum robustness.
- Builtin reopening of all log files in your application via USR1 signal. This allows logrotate to rotate files atomically and quickly via rename instead of the racy and slow copytruncate method. unicorn also takes steps to ensure multi-line log entries from one request all stay within the same file.
- nginx-style binary upgrades without losing connections. You can upgrade unicorn, your entire application, libraries and even your Ruby interpreter without dropping clients.
- transparent upgrades using systemd socket activation is supported.
- before_fork and after_fork hooks in case your application has special needs when dealing with forked processes. These should not be needed when the “preload_app” directive is false (the default).
- Can be used with copy-on-write-friendly GC in Ruby 2.0+ to save memory (by setting “preload_app” to true).
- Supports listening on multiple interfaces including UNIX sockets, each worker process can also bind to a private port via the after_fork hook for easy debugging.
- Simple and easy Ruby DSL for configuration.
- Decodes chunked requests on-the-fly.
Support: Source Code Repository
Developer: The Unicorn Community
License: GPLv2 or later (GPLv3+ preferred), or Ruby (1.8)-specific terms
unicorn is written in Ruby. Learn Ruby with our recommended free books and free tutorials.
Return to Ruby Application Servers Home Page
|The largest compilation of the best free and open source software in the universe. Each article is supplied with a legendary ratings chart helping you to make informed decisions.|
|Hundreds of in-depth reviews offering our unbiased and expert opinion on software. We offer helpful and impartial information.|
|Replace proprietary software with open source alternatives: Google, Microsoft, Apple, Adobe, IBM, Autodesk, Oracle, Atlassian, Corel, Cisco, Intuit, and SAS.|
|Machine Learning explores practical applications of machine learning and deep learning from a Linux perspective. This is a new series.|
|New to Linux? Read our Linux for Starters series. We start right at the basics and teach you everything you need to know to get started with Linux.|
|Alternatives to popular CLI tools showcases essential tools that are modern replacements for core Linux utilities.|
|Essential Linux system tools focuses on small, indispensable utilities, useful for system administrators as well as regular users.|
|Linux utilities to maximise your productivity. Small, indispensable tools, useful for anyone running a Linux machine.|
|Surveys popular streaming services from a Linux perspective: Amazon Music Unlimited, Myuzi, Spotify, Deezer, Tidal.|
|Saving Money with Linux looks at how you can reduce your energy bills running Linux.|
|Home computers became commonplace in the 1980s. Emulate home computers including the Commodore 64, Amiga, Atari ST, ZX81, Amstrad CPC, and ZX Spectrum.|
|Now and Then examines how promising open source software fared over the years. It can be a bumpy ride.|
|Linux at Home looks at a range of home activities where Linux can play its part, making the most of our time at home, keeping active and engaged.|
|Linux Candy reveals the lighter side of Linux. Have some fun and escape from the daily drudgery.|
|Getting Started with Docker helps you master Docker, a set of platform as a service products that delivers software in packages called containers.|
|Best Free Android Apps. We showcase free Android apps that are definitely worth downloading. There's a strict eligibility criteria for inclusion in this series.|
|These best free books accelerate your learning of every programming language. Learn a new language today!|
|These free tutorials offer the perfect tonic to our free programming books series.|
|Linux Around The World showcases usergroups that are relevant to Linux enthusiasts.|
|Stars and Stripes is an occasional series looking at the impact of Linux in the USA.|