Deploying Grape: REST APIs, done Ruby-style.: what should I watch out for? (#1)

Grape's built-in logger writes to $stdout by default in newer versions — good. On older versions (<1.6) wire it up explicitly, or you'll fly blind in production.

Deploying Grape: REST APIs, done Ruby-style.: what should I watch out for? (#2)

grape-swagger's generated OpenAPI is not free — it walks every endpoint at boot. Cache the doc at build time if boot latency matters.

Deploying Grape: REST APIs, done Ruby-style.: what should I watch out for? (#3)

When mounted in Rails, Grape does NOT go through ApplicationController — session, CSRF and current_user helpers are unavailable. Use a shared middleware instead.

// framework · grape

Grape: REST APIs, done Ruby-style.

Q: Deploying Grape: REST APIs, done Ruby-style.: what should I watch out for? (#2)

grape-swagger's generated OpenAPI is not free — it walks every endpoint at boot. Cache the doc at build time if boot latency matters.

Q: Deploying Grape: REST APIs, done Ruby-style.: what should I watch out for? (#3)

When mounted in Rails, Grape does NOT go through ApplicationController — session, CSRF and current_user helpers are unavailable. Use a shared middleware instead.

The framework of choice for Ruby-first API teams. Mount it in Rails, or run it standalone on a lean Puma. Deploys like any other Rack app.

Grape is a DSL for HTTP APIs — versioning, param validation, and entity presenters, without the ceremony of a full framework. This guide covers both deployment modes: mounted inside a Rails app and standalone Rack on Puma.

118 MB

min container size (standalone)

~3.8k

req/s on 1 vCPU (standalone)

6 ms

typical p50 latency

01 / 04

Standalone Rack: the lean path

For pure-API services, skip Rails. A Grape app on Puma is a ~120 MB container that boots in under 300 ms — ideal for Cloud Run, Fargate or Container Apps.

ruby
# config.ru
require "grape"

class API < Grape::API
  format :json
  version "v1", using: :path
  resource :ping do
    get { { pong: Time.now.utc.iso8601 } }
  end
end

run API

02 / 04

Mounted in Rails

For teams already running Rails, mount Grape at /api and share the same deploy pipeline. No infra changes — just add the gem and a route.

ruby
# config/routes.rb
mount API => "/api"

03 / 04

Versioning belongs in the URL

Grape supports header- and param-based versioning, but URL versioning (/v1/…) is the only kind CDNs and API gateways cache correctly. Pick it and never look back.

04 / 04

Entities, not to_json

Use Grape::Entity (or grape-swagger for OpenAPI) to lock down response shapes. Model.to_json leaks fields the day someone adds a column — an audit-log waiting to happen.

Gotchas we learned the hard way

!Grape's built-in logger writes to $stdout by default in newer versions — good. On older versions (<1.6) wire it up explicitly, or you'll fly blind in production.
!grape-swagger's generated OpenAPI is not free — it walks every endpoint at boot. Cache the doc at build time if boot latency matters.
!When mounted in Rails, Grape does NOT go through ApplicationController — session, CSRF and current_user helpers are unavailable. Use a shared middleware instead.