Mention rack 2.1.0 support in UPGRADING.md

[maxkerp]

I'm currently upgrading a fairly big rails app I did not write myself which uses grape. Since I unfortunately never used grape before (I want to though 😉), I was in unknown territory and it took me quite I while to figure out that grape added support for rack >= 2.1.0 first on 1.3.0.

First thing I did when running into [https://github.com//issues/1966](this error) was checking the Upgrade.md file for any signs of rack incompatibility, but I did not find any. I wish I did, since it took me a few hours to find the mentioned issue. (I really have to up my google-fu, I know 🙈)

But for any poor soul in the future, who is just as bad as googling as I am, it might be helpful to mention this in the Upgrade guide :)

[grape-bot]

	1 Warning
⚠️	Unless you’re refactoring existing code, please update CHANGELOG.md.

Here's an example of a CHANGELOG.md entry:

* [#2130](https://github.com/ruby-grape/grape/pull/2130): Mention rack 2.1.0 support in upgrading.md - [@maxkerp](https://github.com/maxkerp).

Generated by 🚫 danger

[dblock]

Thanks! Explain what the developer that's upgrading has to do though? Does one have to upgrade and therefore add a specific version of Rack to Gemfile? Link to the issue?

[maxkerp]

Well that got merged fast 😁 Always feels good to contribute to oss, even when it's a tiny bit ☺️
(Edit: Ehmm, I just realized that the PR is still open. I don't know why I thought it was already merged 😅 Anyway, I'm glad I can help and let me know if I can improve on this 😃)

I had the option to either upgrade to grape >= 1.3.0 or ensure that we are using a compatible version of rack.

Since I want to wait with the upgrade of grape til we are done with the upgrade to rails 5.0 I opted to pin the version of rack to ~> 2.0.0 so it will be below version 2.1.0.

Since rack isn't part of a Gemfile in rails project per se I needed to add it altogether like this:

gem 'rack', '~> 2.0.0'

I will remove this line from my Gemfile once I'm done upgrading to grape >= 1.3.0 :)

Does this answer your questions?

[dblock]

First, thanks. But I am looking for a sentence of instructions below the line that you're adding to the user UPGRADING. So I am confused to what we're trying to tell the user. UPGRADING instructions should tell users what to do, CHANGELOG says what changed and feels like we're mixing the two.

[maxkerp]

Know I understand and I think this is kind of tricky. The information I thought I might find here is the incompatibility of grape versions with other "big" gems/dependencies. When I looked at the file I wasn't looking for instructions of how I upgrade to a specific version, but rather of why I would want to.

The line I added tells me that versions <= 1.3.0 don't work with rack >= 2.1.0 and from there I can decide what to do next. This is probably very project specific. Pinning the rack version worked for me, but might not for someone else.

So if you are looking for instructions it might be something like

In the section "Upgrading to >= 1.3.0":

"You will need to upgrade to this version if you depend on rack >= 2.1.0"

Or in the section "Upgrading to >= 1.2.5":

"If something prevents you from upgrading to version >= 1.3.0 it might be helpful to pin rack to ~> 2.0.0 in your Gemfile, since version 1.2.5 does not work with rack >= 2.1.0"

What do you think?

[dblock]

Your suggestions sound good! Go for it.

[maxkerp]

Sorry I totally forgot about this 😅 In case it's still relevant I updated it ✌️

[dblock]

Thanks. Can I nitpick?

[dblock]

It's missing a period.

[maxkerp]

Sure, you can. Added it ✌️