Provide a mechanism to auto-reload a Grape application

[lexer]

Grape app mounted to Rails is not reloaded on each request in development mode. Or may be I haven't configured it properly?

[mbleigh]

You'll find the same of Sinatra or any other Rack framework that you mount into a Rails app. Rails reloading is very specialized and doesn't "automatically" carry over to other frameworks. It's something we may consider in the future, but for now it's out. Sorry!

[mhenrixon]

This is really too bad because it makes it really frustrating to testin using guard and spork. How are people solving this today? Manually restart everything because spork/guard doesn't realize the api file has changed can't be very complicated in my scenario when it's just one file to reload but I can't make it happen.

Any suggestions to that? Going to the console and running rspec feels so 1999.

[mhenrixon]

@lexer you might want to have a look at mounting the app in config.ru instead of in the routes. That's how resque recommends mounting because of similar reasons and of course the assets reasons but I think it gives some benefits.

https://github.com/defunkt/resque/blob/master/examples/demo/config.ru

[mbleigh]

If you write your Grape app as an independent application you can have a separate set of tests just for it that will be quick. I have a Grape application with several hundred tests, no spork or anything like that, and it can load and execute the tests in less than 10 seconds.

[mhenrixon]

Sure but how do you share your rails app with that in a sane manner? I don't want to duplicate all the models and such and unfortunately writing the API after building the website.

Still haven't seen a good example of how to share all that code without some serious work.

I'd love to make the API truly independent because then I can host the API outside of the web app which gives a multitude of benefits but the pain of sharing the data access code is still putting me off.

[mhenrixon]

@mbleigh would you be using something like just activerecord outside rails like here http://blog.aizatto.com/2007/05/21/activerecord-without-rails/ ?

[dblock]

I am going to reopen this as a feature request. We do, in theory, want to provide a railtie to automatically reload a Grape API as well as a mechanism that works well with guard. It could be an external solution too. Any suggestions on how to accomplish this are welcome.

[mbleigh]

TL;DR I'm open to unobtrusive reloading, but I won't be working on it myself.

I guess it's true that we want reloading in an ideal world, but the "in practice" of this seems pretty unlikely. Especially now that there are mountable applications I can't really think of anything that can rebuild the application state short of reloading everything on every request, at which point we may as well not have reloading.

I also think that much of the impetus for wanting reloading is based on the use case of mounting Grape APIs inside of Rails. While I certainly want to support this use case, the reality is that Rails simply takes too long to boot and that's not Grape's fault. As I said, a bare Grape application can run hundreds of tests in about 10 seconds (with about 2 of those being boot time).

[mbleigh]

Haha, though now that I think about it since rebooting Grape is relatively fast, that's probably the solution right there. I don't know how you would do it, but completely blowing away all API classes and reloading them from scratch on each request would solve the Rails use case even if it would have no effect on bare apps.

[dblock]

I looked at implementing a Grape::API::reload!, very briefly. If something like that existed it would be trivial to add Rack::Reloader in front of it (which would reload individual files) and probably easy to trigger reload! if anything within the API were to change. That would work for Rails out of the box.

An alternative would be to look at how ActiveSupport does dependencies to trigger reloading, but either way we need something in Grape proper that dumps the existing API endpoint and recreates it from scratch.

For bare Rack applications that are rackup-ed you can use Guard with fresh-from-this-morning guard-rack gem.

[mhenrixon]

@mbleigh that's exactly what needs to be done for the sake of sanity when developing something inside a rails app which after all is a pretty common scenario (my opinion based on searching and issues).

I actually just switched back to using all the extra controllers and all the extra files and rails built in methods of api building just because having to start and stop the API. I would have much rather used Grape but when tests won't pass without restarting guard it's just too frustrating.

[mbleigh]

I'm not terribly familiar with how reloading works but if it's simply a matter of resetting the internal data structures of an API that is actually pretty damn easy. If other libraries can take up the remainder of the work I'm happy to provide an API.reset! that will empty things out.

[mbleigh]

Note: by happy to provide I mean "There's already an API.reset! method"