fix docker builds to run gem update system with gem-update pinned to …

…specific version that is compatible with ruby 2.7 (#4275)

* fix docker builds to run gem update system with gem-update pinned to specific version that is compatible with 2.7

* update comments on why we pin gem-update and why updating system

* update comment with troubleshooting docs from miniracer readme

---------

Co-authored-by: Zach Wolfenbarger <[email protected]>

Dockerfile

@@ -31,6 +31,11 @@ ADD ./Gemfile /rails_app/
 ADD ./Gemfile.lock /rails_app/
 
 RUN bundle config --global jobs `cat /proc/cpuinfo | grep processor | wc -l | xargs -I % expr % - 1`
+
+# run gem update system so installation of mini_racer does not fail
+# See troubleshooting for mini_racer and supported ruby versions: https://github.com/rubyjs/mini_racer?tab=readme-ov-file#supported-ruby-versions--troubleshooting
+# pinning gem update to 3.4.22 since anything higher requires updating Ruby version to 3+
+RUN gem i "rubygems-update:~>3.4.22" --no-document && update_rubygems
 RUN bundle install --without development test
 
 ADD ./ /rails_app

Dockerfile.dev

@@ -19,6 +19,11 @@ ADD ./Gemfile /rails_app/
 ADD ./Gemfile.lock /rails_app/
 
 RUN bundle config --global jobs `cat /proc/cpuinfo | grep processor | wc -l | xargs -I % expr % - 1`
+
+# run `gem update system` so installation of mini_racer does not fail
+# See troubleshooting for mini_racer and supported ruby versions: https://github.com/rubyjs/mini_racer?tab=readme-ov-file#supported-ruby-versions--troubleshooting
+# pinning gem update to 3.4.22 since anything higher requires updating Ruby version to 3+
+RUN gem i "rubygems-update:~>3.4.22" --no-document && update_rubygems
 RUN bundle install
 
 ADD ./ /rails_app