Make docker registry volume configurable

One use case is to use seperate disk for the registry storage. This
can prevent the rootfs from filling up.

Change-Id: I9634ee7f5730e93b8ddd96de04982d638dd4dae2

ansible/group_vars/all/docker-registry

@@ -18,3 +18,6 @@ docker_registry_env: {}
 # NOTE: This is set to 4000 rather than the default of 5000 to avoid clashing
 #       with keystone.
 docker_registry_port: 4000
+
+# Name or path to use as the volume for the docker registry.
+docker_registry_datadir_volume: docker_registry

ansible/roles/docker-registry/README.md

@@ -25,6 +25,8 @@ to ``true``.
 ``docker_registry_restart_policy``: Docker restart policy for
 ``docker_registry`` container. Defaults to ``unless-stopped``.
 ``docker_registry_restart_retries``: Number of Docker restarts. Defaults to 10.
+``docker_registry_datadir_volume``: The name or path to use for the docker
+volume that backs the registry. Defaults to ``docker_registry``.
 
 Dependencies
 ------------

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

@@ -28,11 +28,15 @@ docker_registry_services:
       - "{{ docker_registry_port }}:5000"
     volumes:
       - "/etc/localtime:/etc/localtime:ro"
-      - "docker_registry:/var/lib/registry"
+      - "{{ docker_registry_datadir_volume }}:/var/lib/registry"
 
 # The port on which the docker registry server should listen.
 docker_registry_port: 5000
 
+# The name or path to use for the docker volume that backs the registry.
+# Defaults to ``docker_registry``.
+docker_registry_datadir_volume: docker_registry
+
 ####################
 # Docker
 ####################

releasenotes/notes/add-variable-docker-registry-datadir-volume-a5ec931a5eb2c59d.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Adds the variable, ``docker_registry_datadir_volume``. This allows you to
+    configure the name or path of the docker volume used for the docker registry.