It is possible to build ISO images on a simple Centos VM (with only 8GB memory) and it should work easily. Please report problems on the mailing list https://lists.akraino.org/g/blueprints/topics with tag #rec

If building for the first time, one needs to install the docker-ce and libguestfs tools (exact commands and list in the ta-ci-build job config).

For subsequent builds:

$ git clone "https://gerrit.akraino.org/r/ta/manifest"

$ git clone "https://gerrit.akraino.org/r/ta/build-tools"

$ ./build-tools/build_images.sh -m ./manifest -w ./work

The rest of the shell scripts you see in the ta-ci-build job are the necessary overheads for the LF logs and ISO uploads.