Deprecation of CentOS 6 images

Deprecation of CentOS 6 images

Starting from the Newton release, the images based on CentOS 6 are available also with CentOS 7, sometimes even with more choices for CentOS 7 version (CDH). This spec propose to deprecate and remove the support for CentOS 6 images.

Problem description

Keeping the support for CentOS 6 is increasinglly difficult.

The cloud image provided by the CentOS team can not be used as it is (lack of resize) so a special image should be prepared. This is documented but the default image, which should be manually regenerated, is hosted on, which will be discontinued.

Also, diskimage-builder’s support for CentOS 6 is not so effective as it should be, as most of the focus is (rightfully) on CentOS 7.

Example of issues which requires a workaround:

A blocker bug right now is:

The (non-blocking, even if they should be blocking) gate jobs for sahara-image-builder fails due to the latter.

Proposed change

The support for CentOS 6 images should be deprecated starting from Pike and removed as soon as the compliance with the follows-standard-deprecation allows us to do it.

The change mainly affects sahara-image-elements. The CentOS 6 would not be built anymore by default while building all the images for a certain plugin and a warning message would be printed if one of them is selected.

The code path which checks for CentOS 6 in Sahara services should be kept as they are and not changed as long as the features is available even if deprecated; after the removal the code can be restructured, if needed, to not consider the CentOS 6 use case.


Keep CentOS 6 support until it is retired officially (November 30, 2020) or until diskimage-builder removes the support, but make sure that the current issues are fixed. A change is needed anyway in the sahara-image-elements jobs, as the building fails right now.

Data model impact


REST API impact


Other end user impact

Users won’t be able to use CentOS 6 as base.

Deployer impact


Developer impact


Sahara-image-elements impact

Most of the described changes are in sahara-image-elements (see above).

Sahara-dashboard / Horizon impact

Minor: remove the reference to CentOS 6 and the default cloud image from the image registration panel when the feature is removed.



Primary assignee:

Work Items

  • do not build CentOS 6 image by default for a certain plugin
  • add a warning message if one of them is requested
  • inform the operators (openstack-operators@) about the change to evaluate the time for the removal




If the change is implemented, the existing jobs for sahara-image-elements will only test the supported images and won’t fail.

Documentation Impact

Add or change the list of supported base images.



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