Ruby
A language and runtime behind Rails and GitLab.
Where It Sits
The small stack marks its layer. Beside it, each related technology links to its own page.
- App
- Framework
- Web Server
- RuntimeRuby
- Containers
- OS
- Hypervisor
- Firmware
- Hardware
- Data
About
Ruby is the runtime behind Ruby on Rails and, through it, GitLab. An app server such as Puma runs the application on it, often with a web server such as nginx in front. It is a rival to the other runtimes, not a layer above them.
How to Spot It
These are signs that a system runs Ruby, seen from outside without signing in, such as a response header, a cookie, a path or a default port. They help you find where it runs across your own estate. A version shown to the world also tells anyone scanning which flaws might apply, so it is worth hiding.
- Response header
Server: WEBrick/1.9.2 (Ruby/3.4.9/2026-03-11)- Response header
X-Powered-By: Phusion Passenger
If It Has a Flaw
A flaw in the Ruby runtime reaches every Ruby application on the host, beneath the level of any one application.
A flaw exposes what runs on it and the data it reaches.
- Application
GitLab- Framework and Libraries
Ruby on Rails- Web and App Servers
Puma- Data
PostgreSQL
Redis
Rivals
Rivals do the same job on the same layer, so a system usually runs one of them in any one place. A flaw in a rival does not reach Ruby.
Stacks and Code
Ruby is part of the common stacks below, and each stack's page shows who runs every layer. Its code arrives from the sources listed, and each source's page says how bad code could get in through it.
- In Common Stacks
- A Rails App on Puma
- Its Code Comes From
RubyGems