Ruby On Rails 4.2 End Of Life
It appears that the answer regarding Rails 4.2 EOL is already answered on http://rubyonrails.org/maintenance/. The key points are:
- "New features are only added to the master branch and will not be made available in patch releases."
- "Only the latest release series will receive bug fixes."
- "For major security issues, the current release series, the next most recent one, and the last additional major series will receive patches and new versions."
- "For minor security issues, the current release series and the next most recent one will receive patches and new versions."
In addition, specifically to Rails 4.2, the release notes for Rails 5.1.0.rc1 states that Rails 4.2 will only receive severe security fixes, otherwise Rails 4.x is unsupported.
UPDATE: Rails 6.0.0 was released on August 15, 2019: https://weblog.rubyonrails.org/2019/8/15/Rails-6-0-final-release/
This marks the official end of support for Rails 4.
The end is nigh! Rails 6.0.0.rc1 was released April 24, 2019. (And now, Rails 6.0.0.rc2 on July 30.) When 6.0.0 final is released in ”a few weeks", that will indicate the end of life for Rails 4 support.
Expect that in September 2019. (I'll update this answer when it ships,) Watch for updates on https://weblog.rubyonrails.org/releases/
If you have not started updating your existing Rails 4 applications to Rails 5, it's time to get on it. The good news is, this major version upgrade looks more straightforward than previous major version upgrades.
Here is a brief overview: https://www.ombulabs.com/blog/rails/upgrades/upgrade-rails-from-4-2-to-5-0.html
Here is the official upgrade document, with more detail: https://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html#upgrading-from-rails-4-2-to-rails-5-0