Travis CI allow you to run any particular command, including Docker, on the top of their Ubuntu Precise/Trusty images. There is no way to choose other images from docker hub in the .travis.yml.
Actually, PackPack is not just for Travis, it can be also used locally:
~/gitrepo$ OS=fedora DIST=24 packpack # Build for Fedora 24
~/gitrepo$ OS=centos DIST=7 packpack # Build for CentOS 7
~/gitrepo$ OS=debian DIST=stretch packpack # Build for Debian Stretch
~/gitrepo$ OS=ubuntu DIST=xenial packpack # Build for Ubuntu Xenial
PackPack automatically bumps version in the RPM spec, packs a source tarball, creates a source RPM and then builds binary packages. You only need a proper RPM spec at `rpm/` and `major.minor` annotated git tag.
