Images
------

The project's core philosophy regarding images is that the toolsets
required to enable the OpenStack services should be applied by
Kubernetes itself. This requires OpenStack-Helm to develop common and
simple scripts with minimal dependencies that can be overlaid on any
image that meets the OpenStack core library requirements. The advantage
of this is that the project can be image agnostic, allowing operators to
use Stackanetes, Kolla, Yaodu, or any image flavor and format they
choose and they will all function the same.

A long-term goal, besides being image agnostic, is to also be able to
support any of the container runtimes that Kubernetes supports, even
those that might not use Docker's own packaging format. This will allow
the project to continue to offer maximum flexibility with regard to
operator choice.

To that end, all charts provide an ``images:`` section that allows
operators to override images. Also, all default image references should
be fully spelled out, even those hosted by Docker or Quay. Further, no
default image reference should use ``:latest`` but rather should be
pinned to a specific version to ensure consistent behavior for
deployments over time.

Today, the ``images:`` section has several common conventions. Most
OpenStack services require a database initialization function, a
database synchronization function, and a series of steps for Keystone
registration and integration. Each component may also have a specific
image that composes an OpenStack service. The images may or may not
differ, but regardless, should all be defined in ``images``.

The following standards are in use today, in addition to any components
defined by the service itself:

-  dep\_check: The image that will perform dependency checking in an
   init-container.
-  db\_init: The image that will perform database creation operations
   for the OpenStack service.
-  db\_sync: The image that will perform database sync (schema
   initialization and migration) for the OpenStack service.
-  ks\_user: The image that will perform keystone user creation for the
   service.
-  ks\_service: The image that will perform keystone service
   registration for the service.
-  ks\_endpoints: The image that will perform keystone endpoint
   registration for the service.
-  pull\_policy: The image pull policy, one of "Always", "IfNotPresent",
   and "Never" which will be used by all containers in the chart.

An illustrative example of an ``images:`` section taken from the heat
chart:

::

    images:
      dep_check: quay.io/stackanetes/kubernetes-entrypoint:v0.1.1
      db_init: quay.io/stackanetes/stackanetes-kolla-toolbox:newton
      db_sync: docker.io/kolla/ubuntu-source-heat-api:3.0.1
      ks_user: quay.io/stackanetes/stackanetes-kolla-toolbox:newton
      ks_service: quay.io/stackanetes/stackanetes-kolla-toolbox:newton
      ks_endpoints: quay.io/stackanetes/stackanetes-kolla-toolbox:newton
      api: docker.io/kolla/ubuntu-source-heat-api:3.0.1
      cfn: docker.io/kolla/ubuntu-source-heat-api:3.0.1
      cloudwatch: docker.io/kolla/ubuntu-source-heat-api:3.0.1
      engine: docker.io/kolla/ubuntu-source-heat-engine:3.0.1
      pull_policy: "IfNotPresent"

The OpenStack-Helm project today uses a mix of Docker images from
Stackanetes and Kolla, but will likely standardize on a default set of
images for all charts without any reliance on image-specific utilities.
