grrdocker/centos_i686 repository overview

We have Travis jobs that use Docker containers to build 32-bit debian and rpm client templates on every github commit. Since there aren't any official 32-bit Ubuntu or Centos images, we have to build our own Docker images and push them to dockerhub. Here's how we built this particular image:

• Install the Community-Edition version of Docker (docker-ce, and not docker, or docker.io)

• Create a new directory somewhere on your filesystem, e.g /tmp/dockerbuild

• Become root ($ sudo su), and cd to the build directory.

• Download the 32-bit Centos 7 release:

  wget http://mirror.centos.org/altarch/7/os/i386/Packages/centos-release-7-3.1611.el7.centos.i686.rpm
  

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• Unpack the release as follows:

  rpm -i centos-release-7-3.1611.el7.centos.i686.rpm --root $PWD/centos7_i686_chroot
  

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• Rebuild the rpm database for the Centos installation:

  rpm --root $PWD/centos7_i686_chroot --rebuilddb
  

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• Install all packages in the base package group; you will need to use the setarch tool to 'fake' a 32-bit architecture, since you will likely be running a 64-bit Linux host:

  linux32 yum --installroot=$PWD/centos7_i686_chroot -y groupinstall base
  

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• Build a gzipped tar archive of the installation directory:

  tar --create --gzip --file centos7_i686.tar.gz --directory centos7_i686_chroot .
  

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• Create a Docker image using the archive you have built:

  cat centos7_i686.tar.gz | docker import - centos_i686:7_base
  

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• Create a copy of this Docker file in the build directory: https://github.com/google/grr/blob/master/docker/Dockerfile.build_centos_i686⁠

• Use the Docker file to build the final 32-bit image:

  docker build -t grrdocker/centos_i686:7 -t grrdocker/centos_i686:latest \
      -f Dockerfile.build_centos_i686 .
  

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• Log into Docker as grrdocker (or any account that is an owner in the grrdocker org): $ docker login

• Push the image to dockerhub with both the '7' and 'latest' tags:

  docker push grrdocker/centos_i686:7 && \
      docker push grrdocker/centos_i686:latest
  

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