Deploying Cuba: micro, fast, boring.: what should I watch out for? (#1)

No ActiveRecord, no session store, no CSRF out of the box. Add Ohm or Sequel, add rack-session, add rack-protection — you're picking the stack.

Deploying Cuba: micro, fast, boring.: what should I watch out for? (#2)

Cuba plugins are loaded at boot with global effect. Don't try to conditionally load them per-request; it won't work the way you think.

Deploying Cuba: micro, fast, boring.: what should I watch out for? (#3)

The routing DSL is order-sensitive. Put more specific routes before catchalls, or you'll debug a 'route never matches' issue that has a two-line fix.

// framework · cuba

Cuba: micro, fast, boring.

Sinatra without the DSL sugar. A few hundred lines of Ruby, built on Rack. Deploys like a dream because there's nothing to it.

Cuba is a micro-framework by Michel Martens, built on top of Rack. It's aggressively minimal — routing, and that's about it — which makes it a superb foundation for high-throughput APIs where every allocation matters.

~200

framework LOC

~5.2k

req/s on 1 vCPU

102 MB

min container size

01 / 03

Rack, Puma, done

Cuba doesn't invent a new deployment model. It's Rack. Puma runs it. The Dockerfile is 12 lines.

ruby
# config.ru
require "cuba"

Cuba.define do
  on get do
    on "hello" do
      res.write "world"
    end
  end
end

run Cuba

02 / 03

Compose with plugins, not with a monolith

Cuba's plugin system (Cuba.plugin Rendering) is how you add ERB, JSON responses, sessions, etc. Add only what you need — that's the whole point.

03 / 03

Threaded Puma is the default

Cuba code tends to be short and non-blocking. Set Puma to 5 threads × 2 workers on a 1 vCPU container and you'll saturate the network before the CPU.

Gotchas we learned the hard way

!No ActiveRecord, no session store, no CSRF out of the box. Add Ohm or Sequel, add rack-session, add rack-protection — you're picking the stack.
!Cuba plugins are loaded at boot with global effect. Don't try to conditionally load them per-request; it won't work the way you think.
!The routing DSL is order-sensitive. Put more specific routes before catchalls, or you'll debug a 'route never matches' issue that has a two-line fix.