docker build error Gem::Ext::BuildError: ERROR: Failed to build gem native extension for mimemagic-0.3.9

ruby-on-rails docker dockerfile ruby-on-rails-5

Modify the Dockerfile to install the shared-mime-info package. E.g. on Debian-based images:
RUN apt-get update && apt-get install -y shared-mime-info
If it still won't work, then you may need to update the mimemagic gem. On your host, update mimemagic in the Rails app's Gemfile/Gemfile.lock. You may need to install shared-mime-info first: If the host is macOS, you may need to run brew install shared-mime-info; if the host is Ubuntu, you may need to run apt-get install shared-mime-info. Then run
bundle update mimemagic
If your Dockerfile downloads the Rails app from a repo, push your changes to that repo first. Or, for testing, modify the Dockerfile to copy in the Rails app from the host instead.

ruby-on-rails docker dockerfile ruby-on-rails-5

If you are using macOS, try the following

 brew install shared-mime-info bundle update mimemagic

And the try to bundle your gem file

CodeHunter