you can build CentOS Images using maas image builder(maas-image-builder) for MAAS.html
Getting a Local Copy of maas-image-builderpython
Please use maas-clustercontroler to install maas-image-builderubuntu
bzr branch lp:maas-image-buildercentos
cd maas-image-builderapi
python setup.py installui
aptitude install python-devcentos7
makehtm
Building CentOS 6 Imageget
maas-image-builder -a amd64 -o centos6-amd64-root-tgz centos --edition 6it
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