V1.3: Overview

Hanami applications use Hanami::Router for routing: a Rack compatible, lightweight and fast HTTP router for Ruby.

The first route

With your favorite editor open apps/web/config/routes.rb and add the following line.

get '/hello', to: ->(env) { [200, {}, ['Hello from Hanami!']] }

Then start the server with bundle exec hanami server and visit http://localhost:2300/hello. You should see Hello from Hanami! in your browser.

Let’s explain what we just did. We created a route; an application can have many routes. Each route starts with an HTTP verb declaration, get in our case. Then we specify a relative URI (/hello for us) and the object that is responsible to respond to incoming requests.

We can use most common HTTP verbs: GET, POST, PUT, PATCH, DELETE, TRACE and OPTIONS.

endpoint = ->(env) { [200, {}, ['Hello from Hanami!']] }

get     '/hello', to: endpoint
post    '/hello', to: endpoint
put     '/hello', to: endpoint
patch   '/hello', to: endpoint
delete  '/hello', to: endpoint
trace   '/hello', to: endpoint
options '/hello', to: endpoint


Hanami is compatible with Rack SPEC, and so the endpoints that we use MUST be compliant as well. In the example above we used a Proc that was fitting our requirements.

A valid endpoint can be an object, a class, an action, or an application that responds to #call.

get '/proc',       to: ->(env) { [200, {}, ['Hello from Hanami!']] }
get '/action',     to: "home#index"
get '/middleware', to: Middleware
get '/rack-app',   to: RackApp.new
get '/rails',      to: ActionControllerSubclass.action(:new)

When we use a string, it tries to instantiate a class from it:

get '/rack-app', to: 'rack_app' # it will map to RackApp.new


Full Rack integration is great, but the most common endpoint that we’ll use in our web applications is an action. Actions are objects responsible for responding to incoming HTTP requests. They have a nested naming like Web::Controllers::Home::Index. This is a really long name to write, that’s why Hanami has a naming convention for it: "home#index".

# apps/web/config/routes.rb
root to: "home#index" # => will route to Web::Controllers::Home::Index

The first token is the name of the controller "home" is translated to Home. The same transformation will be applied to the name after the #: "index" to Index.

Hanami is able to figure out the namespace (Web::Controllers) and compose the full class name.

Mounting Applications

If we want to mount an application, we should use mount within the Hanami environment configuration file. The global configuration file is located at config/environment.rb. Place mount within the Hanami.configure block.

Hanami.configure do
  mount Web::Application, at: '/'
  mount OtherApplication.new, at: '/other'


Mounting To A Path

mount SinatraApp.new, at: '/sinatra'

All the HTTP requests starting with /sinatra will be routed to SinatraApp.

Mounting On A Subdomain

mount Blog.new, host: 'blog'

All the HTTP requests to http://blog.example.com will be routed to Blog.

In development, you will NOT be able to access http://blog.localhost:2300, so you should specify a host when running the server: bundle exec hanami server --host=lvh.me. Then your application can be visited at http://blog.lvh.me:2300