zuul-jobs/roles/run-buildset-registry/README.rst
James E. Blair e7a0f0da8b run-buildset-registry: run a dual registry
The docker registry daemon can either act as a private registry,
or as a pull-through proxy, but not both.  Yet we need to be able
to serve private (speculative buildset) images as well as plain
upstream images.  Our registry is used as a mirror and requires
authentication, therefore docker's normal behavior of falling back
on docker.io won't work because it will attempt to use our
credentials.

However, the registry daemon stores all of its state in the
filesystem, therefore we can run two instances of the registry
service, both pointing at the same data store.  The first acts
as a pull-through proxy and will serve whatever files are already
in the local storage, or will fetch them from docker.io.  The second
can be used to upload images into the local storage.

To make a long story short, whenever we push into the buildset
registry, we will use the second endpoint.  Whenever the docker
daemon pulls from the buildset registry, it will use the first.

Change-Id: I296029068b5ef28ee56543741fe8c8deeefb5dfa
2019-02-21 13:49:49 -08:00

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Runs a docker registry for the use of this buildset.
This may be used for a single job running on a single node, or it may
be used at the root of a job graph so that multiple jobs running for a
single change can share the registry. Two registry endpoints are
provided -- one is a read-only endpoint which acts as a pull-through
proxy and serves upstream images as well as those which are pushed to
the registry. The second is intended only for pushing images.
**Role Variables**
.. zuul:rolevar:: buildset_registry_root
:default: {{ ansible_user_dir }}/buildset_registry
Path for the registry volumes.
**Return Values**
.. zuul:rolevar:: buildset_registry
Information about the registry.
.. zuul:rolevar:: host
The host (IP address) of the registry.
.. zuul:rolevar:: port
The port on which the registry is listening.
.. zuul:rolevar:: push_host
The host (IP address) to use when pushing images to the registry.
.. zuul:rolevar:: push_port
The port to use when pushing images to the registry.
.. zuul:rolevar:: username
The username used to access the registry via HTTP basic auth.
.. zuul:rolevar:: password
The password used to access the registry via HTTP basic auth.
.. zuul:rolevar:: cert
The (self-signed) certificate used by the registry.