Some Ruby gems depend on C/C++ native extensions which are platform dependent. nokogiri is one of
these. Fortunately, Traveling Ruby provides a solution
to include native extensions for several specific platforms. However, those extensions provided by
Traveling Ruby are quite obsolete and it is quite non-trivial to build those packages using
Traveling Ruby. I encountered failures with yum update in the chroot environment every now and
then. Thus, I would rather build it on my own.
As a workaround, we can build specific library in centos:centos6 container and copy those
extensions after the build. Note that the final artifact of an extension should contain the
following (use nokogiri as an example), which can be found at your bundle --path:
2.2.0
└── extensions
└── x86_64-linux
└── 2.2.0-static
└── nokogiri-1.8.2
├── gem.build_complete
├── gem_make.out
├── mkmf.log
└── nokogiri
└── nokogiri.so
What really matters here is the *.so file, which is what we're trying to make here. Once that is
ready, you can copy it to its corresponding directory and zip it up as *.tar.gz, e.g.,
nokogiri-1.8.2.tar.gz.
The Dockerfile provided in the directory will generate nokogiri-1.8.2.tar.gz and
store it into /opt/build/target. And we can use this tarball as an upgrade for the one Traveling Ruby provides. To build native extensions for more gems, add those gem into Gemfile, and run the
following:
$ docker build -t rubygem-native-builder .
$ docker cp rubygem-native-builder:/opt/build/target /path/to/host/directory
Currently, it only builds native extensions for x86_64 Linux. Have fun!