Pipelines

A pipeline is the ordered set of HTTP::Handler-compatible pipes applied to a group of routes. The V2 web template generates this configuration.

File: config/routes.cr — this is the generated baseline. Edit the existing pipelines in place; do not create a second Amber::Server.configure block only to change their order.

Amber::Server.configure do
  pipeline :web do
    plug Amber::Pipe::Error.new
    plug Amber::Pipe::Logger.new
    plug Amber::Pipe::Session.new
    plug Amber::Pipe::Flash.new
    plug Amber::Pipe::CSRF.new
  end

  pipeline :static do
    plug Amber::Pipe::Error.new
    plug Amber::Pipe::Static.new("./public")
  end

  routes :web do
    get "/", HomeController, :index
  end

  routes :static do
    get "/*", Amber::Controller::Static, :index
  end
end

Order is behavior. Session must run before Flash, and error handling should wrap work that can fail. Add authentication, rate limiting, or application headers deliberately to only the pipelines that need them.

A protected pipeline

Define a second pipeline when a route group needs additional handling.

File: config/routes.cr — add both the :admin pipeline and its route group inside the existing Amber::Server.configure block.

Amber::Server.configure do
  pipeline :admin do
    plug Amber::Pipe::Error.new
    plug Amber::Pipe::Logger.new
    plug Amber::Pipe::Session.new
    plug Amber::Pipe::Flash.new
    plug AuthenticateAdmin.new
    plug Amber::Pipe::CSRF.new
  end

  routes :admin, "/admin" do
    get "/", AdminController, :index
  end
end

Custom pipes implement call(context) and invoke the next handler when the request should continue. Put AuthenticateAdmin in its own source file, for example src/pipes/authenticate_admin.cr, and require that file from the application before config/routes.cr is compiled. A pipe that finalizes a response can stop the chain.