you can build CentOS Images using maas image builder(maas-image-builder) for MAAS.
Getting a Local Copy of maas-image-builder
Please use maas-clustercontroler to install maas-image-builder
bzr branch lp:maas-image-builder
cd maas-image-builder
python setup.py install
aptitude install python-dev
make
Building CentOS 6 Image
maas-image-builder -a amd64 -o centos6-amd64-root-tgz centos --edition 6
Building CentOS 7 Image
maas-image-builder -a amd64 -o centos7-amd64-root-tgz centos --edition 7
Getting maas-auth key and logging to API
maas-region-admin apikey --username=root
maas login maas http://10.1.35.12/MAAS/api/1.0
Checking for CentOS images if available boot images
maas maas boot-resources read | egrep -i "centos"
Uploading CentOS6 Image
maas maas boot-resources create name=centos/centos6 architecture=amd64/generic content@=/root/maas-image-builder/centos6-amd64-root-tgz
Uploading CentOS7 Image
maas maas boot-resources create name=centos/centos7 architecture=amd64/generic content@=/root/maas-image-builder/centos7-amd64-root-tgz
Checking for CentOS images available boot images
maas maas boot-resources read | egrep -i "centos"
reference: https://maas.ubuntu.com/docs/os-support.html
