I believe the issue may have started with this commit:
Which changed the Bundler version from 1.17.3 to 2.2.9 – based on the error message:
/usr/local/lib/ruby/gems/2.5.0/gems/bundler-1.17.2/lib/bundler/lockfile_parser.rb:238:in parse_spec': undefined method dependencies’ for nil:NilClass (NoMethodError)
It looks like bundler-1.17.2 is still trying to be used in the container, likely causing the mismatch and issues. You can set the specific version of Bundler in your Gemfile like the following:
gem 'bundler', '2.2.9'
You will likely also want to add the following run steps to your config.yml before your bundle install after adding that gem to ensure it’s installed before the bundle install: