Gemfile - add Rack and RDoc for testing - failures with Ruby 2.4 & 2.5

[MSP-Greg]

This seems to intermittently fail. The RubyGems that ships with Ruby 2.4 and 2.5 is not compatible with the Psych version that can be installed.

RDoc has a dependency on Psych. Rack is added just so bundle install --jobs 4 probably needs to run a job after Psych is installed.

This is the weird failure that I spoke of, which is why I had gem update --system in the PR.

[MSP-Greg]

I believe this problem is about dependencies within the std-lib/bundled gems. Psych runs CI with its tests running against core Ruby. So, it does work with core Ruby 2.4 & 2.5. Problem is, it doesn't work with the RubyGems in 2.4 & 2.5.

How to fix?

EDIT: I assumed, but I was wrong. It also involves the cache. See https://github.com/MSP-Greg/ruby-setup-ruby/actions/runs/1705378024, which shows the failures, and was done from the same branch as this PR...

[MSP-Greg]

@deivid-rodriguez @eregon

Deivid, sorry for the ping. Noticing some odd things with Actions.

Let's say I have a Gemfile which installs Psych, which currently is compatible with Ruby 2.4 and later. There is no Gemfile.lock file, and all the gems are installed in vendor/bundle, which is set with bundle config. Bundler is updated, but not RubyGems.

With Ruby 2.5 (and maybe sometimes 2.4, not sure), running bundle install seems to generate errors like:

  --- ERROR REPORT TEMPLATE -------------------------------------------------------
  
  ArgumentError: wrong number of arguments (given 4, expected 1)
    /home/runner/work/ruby-setup-ruby/ruby-setup-ruby/vendor/bundle/ruby/2.5.0/gems/psych-4.0.3/lib/psych.rb:323:in `safe_load'
    /opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/safe_yaml.rb:31:in `safe_load'
    /opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package.rb:496:in `block (2 levels) in read_checksums'

This is the situation when Action's restores a Bundle cache. I haven't tried it locally yet, wondering if you think this may be the issue? It doesn't seem to happen if vendor/bundle isn't populated with gems, similar to the cache not being used in Actions...

[dentarg]

Here's example runs of the issue @MSP-Greg talks about above

• bundler-cache: false Ruby 2.5 works: https://github.com/dentarg/puma/runs/4834198864?check_suite_focus=true#step:9:71
• bundler-cache: true Ruby 2.5 fails: https://github.com/dentarg/puma/runs/4837582771?check_suite_focus=true#step:4:2054

[deivid-rodriguez]

I did't have a close look, but the issue is indeed RubyGems depending on Psych internally. This has been partly address in recent RubyGems versions by supporting both Psych 3 and 4, so the solution is to update RubyGems when it's not modern enough to include that fix. Since ruby/setup-ruby has accepted to allow updating RubyGems, that seems enough to address this issue, no? Of course, someone has to implement it, but in the mean time I guess you can give up on bundler-cache and update RubyGems manually.

What I mean is that yes, this issue is intermittent depending on whether Bundler ends up hitting the Psych 4 interface old RubyGems is not compatible with. But it doesn't seem worth to me digging further given that upgrading RubyGems fixes the issue in general.

[MSP-Greg]

1. I have repo'd this locally. Psych needs to be in the Gemfile, and I believe bundle install needs the --jobs option.
2. Found an example of this happening about 3 weeks ago, see https://github.com/ruby/rdoc/runs/4646871718?check_suite_focus=true#step:3:57. Note that the CI was updating RubyGems for Ruby 2.5 and 2.6 after setup-ruby.

Now, this is breaking CI for repos, but it's nothing to do with the action. Since the action allows bundle install within it, what to do?

One option is to add an input for RubyGems. I'm not sure what I think of that, or the possible support problems with its interaction with a Bundler input.

Another option might be to add bundler options of something like gem-update-sys-fix and gem-update-sys-all. The first would run gem update --system for Rubies 2.3 thru 2.6, the second would do so for 2.3 thru 3.1. Obviously, this would install Bundler 2 also.

Thoughts?

[deivid-rodriguez]

If I understood correctly, @eregon accepted a rubygems input, it only needs someone to implement it.