Class: Condux::Rack::CaptureExceptions

Inherits:
Object
  • Object
show all
Defined in:
lib/condux/rack.rb

Overview

Rack middleware: report an uncaught exception (as unhandled) and re-raise, so the app's own error handling still runs. Covers Rails and any Rack app.

# config.ru (Rack)
require "condux/rack"
use Condux::Rack::CaptureExceptions

# Rails (config/application.rb)
config.middleware.use "Condux::Rack::CaptureExceptions"

ON RAILS, USE config.middleware.use AND NOTHING ELSE.

use APPENDS, which puts this at the very bottom of the stack, inside ActionDispatch's ShowExceptions and DebugExceptions. That position is the whole reason it works: those two catch a controller exception and turn it into a 500, so anything above them never sees the exception at all and would report nothing, silently. Verified against a real Rails app, where this lands at position 21 with ShowExceptions at 9.

So insert_before, insert_after or unshift will move it above them and it will stop reporting with no error to tell you. A future Rails release reordering its own stack could do the same, which is why the position is pinned by a test rather than only described here.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ CaptureExceptions

Returns a new instance of CaptureExceptions.



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# File 'lib/condux/rack.rb', line 29

def initialize(app)
  @app = app
end

Class Method Details

.request_fields(env) ⇒ Object

The request, in the Sentry store shape the relay parses.

Deliberately only the path, method and query string. Rack puts headers in HTTP_* keys, including HTTP_COOKIE and HTTP_AUTHORIZATION; the relay scrubs sensitive keys at ingest, but not sending credentials at all is the stronger guarantee.



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# File 'lib/condux/rack.rb', line 50

def self.request_fields(env)
  {
    "url" => env["PATH_INFO"],
    "method" => env["REQUEST_METHOD"],
    "query_string" => env["QUERY_STRING"]
  }.reject { |_key, value| value.nil? || value.empty? }
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/condux/rack.rb', line 33

def call(env)
  # A scope per request, so a set_user in a controller belongs to that request and cannot attach to
  # a concurrent one. Puma reuses threads, which is exactly why this has to be scoped rather than
  # left to process state.
  Condux.request_scope do
    @app.call(env)
  rescue StandardError => e # report anything the app raises, then re-raise
    Condux.capture_exception(e, handled: false, request: self.class.request_fields(env))
    raise
  end
end