Use version range instead of OSEM_RUBY_VERSION.

[AndrewKvalheim]

Checklist

• I have read the Contribution & Best practices Guide.
• My branch is up-to-date with the upstream master branch.
• The tests pass locally with my changes.
• I have added tests that prove my fix is effective or that my feature works (if appropriate).
• I have added necessary documentation (if appropriate).

Short description of what this resolves

In order to accommodate variation in the version of Ruby across environments, the Gemfile is currently runtime-configurable via OSEM_RUBY_VERSION:

osem/Gemfile

Line 5 in e6f3aa5

ruby ENV['OSEM_RUBY_VERSION'] || '2.5.0'

This mechanism is incompatible with typical Docker environments since, by design, the runtime configuration has no effect on builds:

$ docker-compose build osem
…
Your Ruby version is 2.5.5, but your Gemfile specified 2.5.0

Furthermore, that it's apparently become routine to circumvent the Ruby specification raises the question of why that constraint exists at all. If users are typically expected to set OSEM_RUBY_VERSION, what purpose does the Ruby specification serve?

Changes proposed in this pull request

As with the other dependencies, specify a range of compatible versions. I've guessed at a conservative starting point:

ruby '~> 2.5.0'

[codecov]

Codecov Report

Merging #2646 into master will increase coverage by 1.64%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2646      +/-   ##
==========================================
+ Coverage    80.5%   82.15%   +1.64%     
==========================================
  Files         146      146              
  Lines        4832     4780      -52     
==========================================
+ Hits         3890     3927      +37     
+ Misses        942      853      -89

Impacted Files	Coverage Δ
app/datatables/user_datatable.rb	100% <0%> (ø)	⬆️
app/models/user.rb	95.03% <0%> (+0.7%)	⬆️
app/helpers/users_helper.rb	92.85% <0%> (+7.14%)	⬆️
app/helpers/events_helper.rb	86.56% <0%> (+13.43%)	⬆️
app/helpers/date_time_helper.rb	92.85% <0%> (+14.28%)	⬆️
app/mailers/mailbot.rb	48.88% <0%> (+15.55%)	⬆️
app/helpers/application_helper.rb	93.47% <0%> (+17.39%)	⬆️
app/serializers/speaker_serializer.rb	100% <0%> (+20%)	⬆️
app/serializers/event_serializer.rb	100% <0%> (+29.16%)	⬆️
app/serializers/track_serializer.rb	100% <0%> (+33.33%)	⬆️
... and 3 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e6f3aa5...8eb696b. Read the comment docs.

[isnuryusuf]

its work for me
solve problem:

Your Ruby version is 2.5.7, but your Gemfile specified 2.5.0
ERROR: Service 'production_web' failed to build: The command '/bin/sh -c export NOKOGIRI_USE_SYSTEM_LIBRARIES=1; bundle install --jobs=3 --retry=3 --without test development' returned a non-zero code: 18

[hennevogel]

We don't really need 2.5, so this would limit us too much. Sorry, thanks anyway 💐

[AndrewKvalheim]

The point is to document what you do need.