Gemfile.lock nof found?

This allowed Ruby apps to be deployed on Linux servers. But since version 2.2, the ruby platform is no longer included by default. Now it's up to each of us to remember to add the appropriate platforms. So, if we plan to deploy to a Linux server, we need to add the Linux platform with this command:

$ bundle lock --add-platform x86_64-linux

In some cases, this is not enough to get the deploy to work. For example, Heroku is still using the older Bundler version 2.1.4, even if your app was bundled with a newer version. It does this by removing the BUNDLED WITH section in your Gemfile.lock before running bundle install. So, if your app was bundled with Bundler version 2.2.x, to be able to deploy it to Heroku, you need to add both the Linux and the Ruby platforms. So, in addition to the command you ran above, run this one as well:

$ bundle lock --add-platform ruby