The packaged version of cloud-init for Fedora and Centos is to old to support the OpenStack network_data.json format. This means that you can't use OpenStack VLAN aware instances or OpenStack baremetal nodes with bonds.
Which version of cloud-init are you using? Fedora 25 currently has cloud-init-0.7.9-4.fc25, which is the latest upstream release.
cloud-init yum installed on Centos7 is 0.7.5 and the version available from EPEL 7 and EPEL testing is also 0.7.5: https://dl.fedoraproject.org/pub/epel/7/x86_64/c/cloud-init-0.7.5-6.el7.x86_64.rpm
EL6 is probably stuck with 0.7.5. There may be bug fixes and similar maintenance but it is unlikely that there will be new feature backports. EL7 will probably see 0.7.9 soon. Fedora, as Garret points out, already has 0.7.9, which is the current upstream release.
This package is no longer included in epel7. https://src.fedoraproject.org/rpms/cloud-init/c/aeebc66ebb93afe224cc4752a58955dad03a5dde?branch=epel7