Make docker registry network mode configurable

Adds a new flag, 'docker_registry_network_mode', which defaults to
'host'. This may be used to set the network mode of the Docker registry
container.

This is a follow up to I404dd52701426a10c2e92727bd52b7fd7112abf6, which
changed the network mode from the default of bridge to host. It allows
that change to be backported to stable branches, without modifying the
default value.

Change-Id: Ic8ec3bb98f8f016e1d089bf10bd0538264394241

ansible/group_vars/all/docker-registry

@@ -14,6 +14,9 @@ docker_registry_enabled: False
 # pull through cache.
 docker_registry_env: {}
 
+# The network mode of the docker registry container. Default is 'host'.
+docker_registry_network_mode: host
+
 # 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

@@ -43,13 +43,17 @@ docker_registry_services:
      {{ {} |
         combine(docker_registry_env_tls if docker_registry_enable_tls | bool else {}) |
         combine(docker_registry_env_basic_auth if docker_registry_enable_basic_auth | bool else {}) |
-        combine(docker_registry_env_listen) |
+        combine(docker_registry_env_listen if docker_registry_network_mode == 'host' else {}) |
         combine(docker_registry_env) }}
     enabled: "{{ docker_registry_enabled }}"
     image: "{{ docker_registry_image_full }}"
-    network_mode: host
+    network_mode: "{{ docker_registry_network_mode }}"
+    ports: "{{ [docker_registry_port ~ ':5000'] if docker_registry_network_mode == 'bridge' else [] }}"
     volumes: "{{ docker_registry_volumes | select | list }}"
 
+# The network mode of the docker registry container.
+docker_registry_network_mode: host
+
 # The port on which the docker registry server should listen.
 docker_registry_port: 5000
 

doc/source/configuration/reference/docker-registry.rst

@@ -27,9 +27,16 @@ Configuring the registry
     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. Default is ``{}``.
+``docker_registry_network_mode``
+    The network mode used for the docker registry container. Default is
+    ``host``. When set to ``bridge``, port mapping is configured to expose the
+    registry through port ``docker_registry_port``.
 ``docker_registry_port``
     The port on which the docker registry server should listen. Default is
-    4000.
+    4000. When ``docker_registry_network_mode`` is set to ``host``, configures
+    the port used by the registry server inside the container. When
+    ``docker_registry_network_mode`` is set to ``bridge``, configures the
+    overlay network port.
 ``docker_registry_datadir_volume``
     Name or path to use as the volume for the docker registry. Default is
     ``docker_registry``.

etc/kayobe/docker-registry.yml

@@ -14,6 +14,9 @@
 # pull through cache. Default is an empty dict.
 #docker_registry_env:
 
+# The network mode of the docker registry container. Default is 'host'.
+#docker_registry_network_mode:
+
 # The port on which the docker registry server should listen. Default is 4000.
 #docker_registry_port:
 

releasenotes/notes/docker-registry-network-mode-3c678295b51d69c1.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Adds a new flag, ``docker_registry_network_mode``, which defaults to
+    ``host``. This may be used to set the network mode of the Docker registry
+    container.