Allow to configure Docker Registry via environment variables

Change-Id: Ida7b870e86894bd33e923ae1cc1142d32e052ddc
Story: 2004817
Task: 28982

ansible/group_vars/all/docker-registry

@@ -5,6 +5,15 @@
 # Whether a docker registry is enabled.
 docker_registry_enabled: False
 
+# Dict of environment variables to provide to the docker registry container.
+# This allows to configure the registry by overriding specific configuration
+# options, as described at https://docs.docker.com/registry/configuration/
+# For example, the registry can be configured as a pull through cache to Docker
+# Hub by setting REGISTRY_PROXY_REMOTEURL to "https://registry-1.docker.io".
+# Note that it is not possible to push to a registry configured as a
+# pull through cache.
+docker_registry_env: {}
+
 # The port on which the docker registry server should listen.
 # NOTE: This is set to 4000 rather than the default of 5000 to avoid clashing
 #       with keystone.

ansible/roles/docker-registry/defaults/main.yml

@@ -8,10 +8,20 @@ docker_registry_action: deploy
 # Whether a docker registry is enabled.
 docker_registry_enabled: true
 
+# Dict of environment variables to provide to the docker registry container.
+# This allows to configure the registry by overriding specific configuration
+# options, as described at https://docs.docker.com/registry/configuration/
+# For example, the registry can be configured as a pull through cache to Docker
+# Hub by setting REGISTRY_PROXY_REMOTEURL to "https://registry-1.docker.io".
+# Note that it is not possible to push to a registry configured as a
+# pull through cache.
+docker_registry_env: {}
+
 # Service deployment definition.
 docker_registry_services:
   docker_registry:
     container_name: docker_registry
+    env: "{{ docker_registry_env }}"
     enabled: "{{ docker_registry_enabled }}"
     image: "{{ docker_registry_image_full }}"
     ports:

ansible/roles/docker-registry/tasks/deploy.yml

@@ -1,6 +1,7 @@
 ---
 - name: Ensure Docker registry container is running
   docker_container:
+    env: "{{ item.value.env }}"
     image: "{{ item.value.image }}"
     name: "{{ item.value.container_name }}"
     ports: "{{ item.value.ports | default(omit) }}"

etc/kayobe/docker-registry.yml

@@ -5,6 +5,15 @@
 # Whether a docker registry is enabled.
 #docker_registry_enabled:
 
+# Dict of environment variables to provide to the docker registry container.
+# This allows to configure the registry by overriding specific configuration
+# options, as described at https://docs.docker.com/registry/configuration/
+# For example, the registry can be configured as a pull through cache to Docker
+# Hub by setting REGISTRY_PROXY_REMOTEURL to "https://registry-1.docker.io".
+# Note that it is not possible to push to a registry configured as a
+# pull through cache.
+#docker_registry_env:
+
 # The port on which the docker registry server should listen.
 #docker_registry_port:
 

releasenotes/notes/docker-registry-env-e954a0642555864f.yaml

@@ -0,0 +1,18 @@
+---
+features:
+  - |
+    Adds support for configuring the Docker Registry by providing environment
+    variables to its container via the ``docker_registry_env`` Ansible
+    variable. For example, the registry can be configured as a pull through
+    cache to Docker Hub using:
+
+    .. code-block:: text
+
+      docker_registry_env:
+        REGISTRY_PROXY_REMOTEURL: "https://registry-1.docker.io"
+
+    Note that it is not possible to push to a registry configured as a
+    pull through cache. See `story 2004817
+    <https://storyboard.openstack.org/#!/story/2004817>`__ for details and the
+    `Docker documentation <https://docs.docker.com/registry/configuration/>`__
+    for the full list of configuration options.