Pipelines
A pipeline is a set of of transformations that is performed to a HTTP request. These transformations come in the form of a pipe. A pipe is a class which includes HTTP::Handler and implements the #call method.
You can use a handler to intercept any incoming request and modify the response. These can be used for request throttling, ip-based whitelisting, adding custom headers.
Every Amber application needs to define a pipeline with a set of pipes each pipeline allow a set of transformations to be applied to different sets of route, this give you granular control and explicitness of which transformation to run for each of the requests.
Amber::Server.configure do |app|
pipeline :web do
# Plug is the method to use connect a pipe (middleware)
# A plug accepts an instance of HTTP::Handler
# plug Amber::Pipe::Params.new
plug Amber::Pipe::Logger.new
plug Amber::Pipe::Flash.new
plug Amber::Pipe::Session.new
plug Amber::Pipe::CSRF.new
end
# All static content will run these transformations
pipeline :static do
plug HTTP::StaticFileHandler.new("./public")
plug HTTP::CompressHandler.new
end
routes :static do
# Each route is defined as follow
# Verb resource : String, controller : Symbol, action : Symbol
get "/*", StaticController, :index
end
routes :web do
get "/", HomeController, :static
end
end
Above we define a pipeline called
:web as you can see the :web pipeline transforms the request using a Logger, StaticFileHandler and a CompressHandler, all of which extends from the Crystal HTTP::Handler class.Amber provides us some default pipes for a number of common tasks. In turn we can customize them as well as create new pipelines to meet our needs.
- Pipe::Static serves static assets
- Pipe::Logger logs incoming requests
- Pipe::CORS Handler adds support for Cross Origin Resource Sharing.
- Pipe::CSRF Handler adds support for Cross Site Request Forgery.
- Pipe::Error Handler catches RouteNotFound and returns.
- Pipe::Flash handler provides a mechanism to pass flash message between
- Pipe::Session a plug that sets up session management.
With our
:web pipeline now define we can use it in our routes definitions.Don't get rid of
StaticController if you need to serve static assets.If you have two pipelines that share a lot of the same pipes, you can assign the shared pipes in one block:
pipeline :web, :auth do ... endFull example for
config/routes.cr:Amber::Server.configure do |app|
pipeline :web, :auth do
plug Amber::Pipe::Logger.new
plug Amber::Pipe::Flash.new
plug Amber::Pipe::Session.new
plug Amber::Pipe::CSRF.new
end
pipeline :auth do
plug Authenticate.new
end
routes :web do
get "/", HomeController, :static
end
routes :auth do
get "/admin", AdminController, :dashboard
end
end
Last modified 6mo ago