I'm trying to make a framework similar to Rails, but purely focused on GraphQL. Once nice feature of Rails is that it provides a CLI interface and a config.ru for Rack. Therefore, you can call rackup or you can call bin/rails server and the Rails app will run. I managed to mimic this functionality by putting the Rack app into a separate file (config/application.rb), which I import in config.ru and in the CLI, then instantiate and run.
However, I have an issue with Rack middleware. Since Rack middleware appears to just magically work when you run use MyMiddleware with an instantiated Rack app, I'm not really sure how I can do this in both config.ru and in my CLI. Right now it looks like I need to instantiate the app in a separate location, add the middleware, then hand it over to config.ru or the CLI. Which, I could do, but it feels like there has to be a way to attach middleware in a cleaner way. For instance, can I require config.ru in some way and then run it? Or can I attach middleware before I instantiate the app?
config.ru is just a ruby file, it's loaded by Rails as part of running each command. You can require it yourself as normal if that's what you'd like to do.
If you want to really figure out how Rails does it, the config loading is buried in this part of the Rails CLI:
https://github.com/rails/rails/blob/3cac5fe94f0f81b4263cfa03d4822c05a55eb49c/railties/lib/rails/application.rb
Related
What is this file config.ru, and what is it for in Sinatra projects? In my lanyard of the project, such code is written:
require './app'
run Sinatra::Application
config.ru is a Rack configuration file (ru stands for "rackup"). Rack provides a minimal interface between web servers that support Ruby and Ruby frameworks. It's like a Ruby implementation of a CGI which offers a standard protocol for web servers to execute programs.
Rack's run command here means for requests to the server, make Sinatra::Application the execution context from which Sinatra's DSL could be used. All DSL methods on the main are then delegated to this class.
So in this config.ru file, first you require your app code which uses Sinatra's DSL then run the Sinatra framework. In the context of Sinatra::Application if your app.rb contained this:
get '/' do
'Hello world!'
end
The get block would mean something to Rack, in this case when someone tries to access (GET) the home url, send back 'Hello world!'
Rack provides a minimal interface between webservers that support Ruby and Ruby frameworks.
The interface just assumes that you have an object that responds to a call method (like a proc) and returns a array with:
The HTTP response code
A Hash of headers
The response body, which must respond to each
You can run a basic Rack server with the rackup command which will search for a config.ru file in the current directory.
You can create a minimal hello world server with:
# config.ru
run Proc.new { |env| ['200', {'Content-Type' => 'text/html'}, ['Hello World']] }
# run this with the `rackup` command
Since Sinatra just like Rails builds on Rack it uses rackup internally to interface between the server and the framework. config.ru is thus the entry point to any Rack based program.
What it does is bootstrap the application and pass the Sinatra::Application class to rack which has a call class method.
Sinatra::Application is then responsible for taking the incoming request (the env) and passing it to the routes your application provides and then passing back the response code, headers, and response body.
config.ru is a default configuration file for a rackup command with a list of instructions for Rack.
Rack is an interface and architecture that provides a domain specific language (DSL) and connects an application with a world of web. In two words, it allows to build web applications and work with requests, responses (and many other web-related technologies) in a most convenient way.
Sinatra as well as Rails are web frameworks, so they both use Rack:
http://recipes.sinatrarb.com/p/middleware
https://guides.rubyonrails.org/rails_on_rack.html
I have a rack based gem, where the user defines routes, and they are then processed by the gem. I an trying to figure out how to test this setup. Testing methods directly impacted by the creation of routes doesn't work, because they are obviously not defined yet, because no app has been created. Is there a solution to this? I am currently using RSpec, and I would really like it if there is an RSpec solution to this.
i use framwork Espresso with Enginery generator (Ruby gems). I create new project, and not understand how work this application. I will work with Espresso. Explain me struct Expresso Application, please.
I can run this apllication: rackup config.ru
I can edit controllers, but i not understand depending between ruby scripts in this project.
i run projects, but why this work it?
config.ru
require File.expand_path('../base/boot', __FILE__)
puts App.urlmap
run App
in project not /base/boot directory.
requiring '../base/boot' will actually load dependencies, controllers, models etc. and build the application.
The application are stored under App constant, so you can access it from different files:
https://github.com/espresso/enginery/blob/master/app/base/base/boot.rb#L9
puts App.urlmap will display all the routes to be served by app.
And run App will start your app.
You can also start app by ruby app.rb, then you do not need to pass server/port at startup.
Instead you'll set them in config/config.yml, like this:
development:
server: Thin
port: 5252
The config.ru file looks quite normal for a rack start-up file. You would start the application from the project folder, with a command like:
rackup -p 8080
The following line:
require File.expand_path('../base/boot', __FILE__)
will load in the ../base/boot file (similar to require_relative, but also works with older Ruby e.g. 1.8.7), which I would guess requires the dependencies where App is defined. The class or module App will implement a call method. To start the server, the rack host calls App.new (which is called due to run App) and then on each request it will call .call( env ) on the resulting object (the object doesn't have to be an App object, but in simpler frameworks it will be).
The variable env contains all the details of the request and the rack environment that can be inspected to fetch details of the current path, cookies, query params etc. Typically access to this data is abstracted through Sinatra and Espresso helper methods that you will use.
The Sinatra and Espresso helper methods look like they are doing magic declarations, but they are just normal methods. Usually they do some calculation and then stash a code block/lambda for rack to call later. Sinatra's get is like this . . . it isn't true declarative code. Instead, when the controller is parsed, it just takes the code block and tells the application object to call it (later) when the path matches.
Is there anything in the Sinatra / Rack world similar to Rails configuration loading scheme that loads one of the config\enviroments\*.rb files depending on Rails.env
I know I could develop one pretty easily, i was just wondering if there was something already in place.
If you're following the Rails convention of putting a file for each environment in config/environments/environment_name.rb, you can put something like this in your Sinatra app, or for Rack in your config.ru file:
Dir.glob(File.dirname(__FILE__) + "/config/environments/#{settings.environment}.rb", &method(:require))
With some minor modifications you could make it load other file locations/combinations. Sinatra's configure blocks work just as well, too.
It turns out that there is something from Sinatra, that provides a similar, though limited, functionality.
See the code:
https://github.com/sinatra/sinatra/blob/master/lib/sinatra/base.rb#L1120
So that you can do this:
class MyApp < Sinatra::Base
configure :development, :test do
#only executes this code when environment is equal to one of the passed arguments
# I'm pretty sure Sinatra sets this based on ENV['RACK_ENV']
end
end
There is one called Sinatra::ConfigFile, which now lives in Sinatra::Contrib http://www.sinatrarb.com/contrib/config_file.html
There's lots of useful stuff in there.
I adapted mine from monkrb.com (it's also yaml in RoR anyways)
YAML.load_file(path_of "config/settings.yml")[RACK_ENV]
e.g.
http://github.com/codepants/yasumi/blob/master/config/settings.yml
I am trying to create Sinatra based heroku app without any luck?
To answer your question: Yes!
For reference: http://docs.heroku.com/rack#sinatra
The sinatra application should be as you always do but on the root of your application you should include a config file named config.ru
It basically says:
require 'application' run
Sinatra::Application
There is a new, slightly different procedure for deploying Sinatra (and other Ruby) apps on Heroku/Cedar which involves "foreman" (and a Procfile)... see getting started guide for Ruby:
http://devcenter.heroku.com/articles/ruby