88 lines
2.9 KiB
Ruby
88 lines
2.9 KiB
Ruby
require 'erb'
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module ActionController
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# The Failsafe middleware is usually the top-most middleware in the Rack
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# middleware chain. It returns the underlying middleware's response, but if
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# the underlying middle raises an exception then Failsafe will log the
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# exception into the Rails log file, and will attempt to return an error
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# message response.
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#
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# Failsafe is a last resort for logging errors and for telling the HTTP
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# client that something went wrong. Do not confuse this with the
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# ActionController::Rescue module, which is responsible for catching
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# exceptions at deeper levels. Unlike Failsafe, which is as simple as
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# possible, Rescue provides features that allow developers to hook into
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# the error handling logic, and can customize the error message response
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# based on the HTTP client's IP.
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class Failsafe
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cattr_accessor :error_file_path
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self.error_file_path = Rails.public_path if defined?(Rails.public_path)
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def initialize(app)
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@app = app
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end
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def call(env)
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@app.call(env)
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rescue Exception => exception
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# Reraise exception in test environment
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if defined?(Rails) && Rails.env.test?
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raise exception
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else
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failsafe_response(exception)
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end
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end
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private
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def failsafe_response(exception)
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log_failsafe_exception(exception)
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[500, {'Content-Type' => 'text/html'}, [failsafe_response_body]]
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rescue Exception => failsafe_error # Logger or IO errors
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$stderr.puts "Error during failsafe response: #{failsafe_error}"
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end
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def failsafe_response_body
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error_template_path = "#{self.class.error_file_path}/500.html"
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if File.exist?(error_template_path)
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begin
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result = render_template(error_template_path)
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rescue Exception
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result = nil
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end
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else
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result = nil
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end
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if result.nil?
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result = "<html><body><h1>500 Internal Server Error</h1>" <<
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"If you are the administrator of this website, then please read this web " <<
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"application's log file to find out what went wrong.</body></html>"
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end
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result
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end
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# The default 500.html uses the h() method.
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def h(text) # :nodoc:
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ERB::Util.h(text)
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end
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def render_template(filename)
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ERB.new(File.read(filename)).result(binding)
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end
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def log_failsafe_exception(exception)
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message = "/!\\ FAILSAFE /!\\ #{Time.now}\n Status: 500 Internal Server Error\n"
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message << " #{exception}\n #{exception.backtrace.join("\n ")}" if exception
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failsafe_logger.fatal(message)
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failsafe_logger.flush if failsafe_logger.respond_to?(:flush)
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end
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def failsafe_logger
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if defined?(Rails) && Rails.logger
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Rails.logger
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else
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Logger.new($stderr)
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end
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end
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end
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end
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