[wolsen,r=] Add support for overriding public endpoint addresses.

Adds in the config option for overriding public endpoint addresses
and introduces a unit tests to ensure that the override for the
public address is functioning correctly.

Closes-Bug: #1398182

config.yaml

@@ -207,6 +207,18 @@ options:
       192.168.0.0/24)
       .
       This network will be used for public endpoints.
+  endpoint-public-name:
+    type: string
+    default:
+    description: |
+      The hostname or address of the public endpoints created for swift-proxy
+      in the keystone identity provider.
+      .
+      This value will be used for public endpoints. For example, an
+      endpoint-public-name set to 'files.example.com' with will create
+      the following public endpoint for the swift-proxy.
+      .
+      https://files.example.com:80/swift/v1
   prefer-ipv6:
     type: boolean
     default: False

hooks/charmhelpers/contrib/openstack/ip.py

@@ -26,8 +26,6 @@ from charmhelpers.contrib.network.ip import (
 )
 from charmhelpers.contrib.hahelpers.cluster import is_clustered
 
-from functools import partial
-
 PUBLIC = 'public'
 INTERNAL = 'int'
 ADMIN = 'admin'
@@ -35,15 +33,18 @@ ADMIN = 'admin'
 ADDRESS_MAP = {
     PUBLIC: {
         'config': 'os-public-network',
-        'fallback': 'public-address'
+        'fallback': 'public-address',
+        'override': 'endpoint-public-name',
     },
     INTERNAL: {
         'config': 'os-internal-network',
-        'fallback': 'private-address'
+        'fallback': 'private-address',
+        'override': 'endpoint-internal-name',
     },
     ADMIN: {
         'config': 'os-admin-network',
-        'fallback': 'private-address'
+        'fallback': 'private-address',
+        'override': 'endpoint-admin-name',
     }
 }
 
@@ -57,15 +58,30 @@ def canonical_url(configs, endpoint_type=PUBLIC):
     :param endpoint_type: str endpoint type to resolve.
     :param returns: str base URL for services on the current service unit.
     """
-    scheme = 'http'
-    if 'https' in configs.complete_contexts():
-        scheme = 'https'
+    scheme = _get_scheme(configs)
+
     address = resolve_address(endpoint_type)
     if is_ipv6(address):
         address = "[{}]".format(address)
+
     return '%s://%s' % (scheme, address)
 
 
+def _get_scheme(configs):
+    """Returns the scheme to use for the url (either http or https)
+    depending upon whether https is in the configs value.
+
+    :param configs: OSTemplateRenderer config templating object to inspect
+                    for a complete https context.
+    :returns: either 'http' or 'https' depending on whether https is
+              configured within the configs context.
+    """
+    scheme = 'http'
+    if configs and 'https' in configs.complete_contexts():
+        scheme = 'https'
+    return scheme
+
+
 def resolve_address(endpoint_type=PUBLIC):
     """Return unit address depending on net config.
 
@@ -78,6 +94,14 @@ def resolve_address(endpoint_type=PUBLIC):
     :param endpoint_type: Network endpoing type
     """
     resolved_address = None
+
+    # Allow the user to override the address which is used. This is
+    # useful for proxy services or exposing a public endpoint url, etc.
+    override_key = ADDRESS_MAP[endpoint_type]['override']
+    addr_override = config(override_key)
+    if addr_override:
+        return addr_override
+
     vips = config('vip')
     if vips:
         vips = vips.split()
@@ -109,38 +133,3 @@ def resolve_address(endpoint_type=PUBLIC):
                          "clustered=%s)" % (net_type, clustered))
 
     return resolved_address
-
-
-def endpoint_url(configs, url_template, port, endpoint_type=PUBLIC,
-                 override=None):
-    """Returns the correct endpoint URL to advertise to Keystone.
-
-    This method provides the correct endpoint URL which should be advertised to
-    the keystone charm for endpoint creation. This method allows for the url to
-    be overridden to force a keystone endpoint to have specific URL for any of
-    the defined scopes (admin, internal, public).
-
-    :param configs: OSTemplateRenderer config templating object to inspect
-                    for a complete https context.
-    :param url_template: str format string for creating the url template. Only
-                         two values will be passed - the scheme+hostname
-                        returned by the canonical_url and the port.
-    :param endpoint_type: str endpoint type to resolve.
-    :param override: str the name of the config option which overrides the
-                     endpoint URL defined by the charm itself. None will
-                     disable any overrides (default).
-    """
-    if override:
-        # Return any user-defined overrides for the keystone endpoint URL.
-        user_value = config(override)
-        if user_value:
-            return user_value.strip()
-
-    return url_template % (canonical_url(configs, endpoint_type), port)
-
-
-public_endpoint = partial(endpoint_url, endpoint_type=PUBLIC)
-
-internal_endpoint = partial(endpoint_url, endpoint_type=INTERNAL)
-
-admin_endpoint = partial(endpoint_url, endpoint_type=ADMIN)