Docker, SELinux and the myth of kernel independence

Recently I built docker images for omnibus builds. Omnibus packages must be built on the target distro so I needed images for centos, debian and ubuntu. Usually I build such docker images on my laptop which is running Ubuntu; I try to make the builds as repeatable as possible using the excellent packer tool and when I publish images I build them again (using a build server) on cloud instances. In this case, I was using GCE CentOS 7 instance to perform the build and I was surprised when a build that was smooth on my laptop failed miserably.
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