
Updates the various operating system elements so that we set the DISTRO_NAME variable for each distro. This env var is used by bin/pkg-map to set the default distribution name for package name mappings. Change-Id: Ib4b05eb7191dd50d25799a0bac51fd15c01b74cb
Use Ubuntu cloud images as the baseline for built disk images.
Overrides:
- To use a non-default URL for downloading base Ubuntu cloud images, use the environment variable DIB_CLOUD_IMAGES
- To download a non-default release of Ubuntu cloud images, use the environment variable DIB_RELEASE
- To use different mirrors rather than the default of archive.ubuntu.com and security.ubuntu.com, use the environment variable DIB_DISTRIBUTION_MIRROR