Hi,
One of the corner case challenges that I have on the builders that do the chained instance, images, media builds is that they consume an internal mirror - but a generic mirror. i.e updates during the day can result in the images that are built later to end up with different content ( for the ones that consume the updates/ repo etc )
To work around this, I'm proposing running a mirror closer to the image-buildsys machine, that only updates at midnight UTC, and will represent the state of play on the calendar date before the timestamped images. eg. the CentOS-7-x86_64-Generic-2014_08_26.qcow2 image will contain updates upto and including all content released till the 25th midnight.
Its likely easier to make this private. But is there value in having this be public ? its only going to be a single node ?
Also, longer term we might need / want to chain this from ci.dev.centos.org runs, so we only include content thats been through the ci process.