Add net config override

Adds the ability to override the os-net-config data for the undercloud.
In some cases, a single bridge with a single physical interface may not
be sufficient for all cases. This will allow for more advanced
customization of the undercloud networking.

The path to a custom os-net-config json template can be specificed in
undercloud.conf with the net_config_override option.

Change-Id: I1fdc62d61eb5d2ea7e9418e40aa8c07173169d35

instack_undercloud/undercloud.py

@@ -181,6 +181,16 @@ _opts = [
                      'to custom configure services beyond what '
                      'undercloud.conf provides')
                ),
+    cfg.StrOpt('net_config_override',
+               default='',
+               help=('Path to network config override template. If set, this '
+                     'template will be used to configure the networking via '
+                     'os-net-config. Must be in json format. '
+                     'Templated tags can be used within the '
+                     'template, see '
+                     'instack-undercloud/elements/undercloud-stack-config/'
+                     'net-config.json.template for example tags')
+               ),
     cfg.StrOpt('inspection_interface',
                default='br-ctlplane',
                deprecated_name='discovery_interface',
@@ -859,6 +869,21 @@ def _generate_environment(instack_root):
     return instack_env
 
 
+def _get_template_path(template):
+    local_template_path = os.path.join(
+        os.path.dirname(__file__),
+        '..',
+        'templates',
+        template)
+    installed_template_path = os.path.join(
+        '/usr/share/instack-undercloud/templates',
+        template)
+    if os.path.exists(local_template_path):
+        return local_template_path
+    else:
+        return installed_template_path
+
+
 def _generate_init_data(instack_env):
     context = instack_env.copy()
 
@@ -872,20 +897,17 @@ def _generate_init_data(instack_env):
     else:
         hiera_entry = ''
 
+    if CONF.net_config_override:
+        net_config_json = open(CONF.net_config_override).read()
+    else:
+        net_config_json = \
+            open(_get_template_path('net-config.json.template')).read()
+
     context['HIERADATA_OVERRIDE'] = hiera_entry
 
-    renderer = pystache.Renderer()
-    local_template_path = os.path.join(
-        os.path.dirname(__file__),
-        '..',
-        'templates',
-        'config.json.template')
-    installed_template_path = \
-        '/usr/share/instack-undercloud/templates/config.json.template'
-    if os.path.exists(local_template_path):
-        template = local_template_path
-    else:
-        template = installed_template_path
+    partials = {'net_config': net_config_json}
+    renderer = pystache.Renderer(partials=partials)
+    template = _get_template_path('config.json.template')
 
     with open(template) as f:
         config_json = renderer.render(f.read(), context)

templates/config.json.template

@@ -24,29 +24,7 @@
     "runbench": "{{DISCOVERY_RUNBENCH}}"
   },
   "os_net_config": {
-   "network_config": [
-     {
-      "type": "ovs_bridge",
-      "name": "br-ctlplane",
-      "ovs_extra": [
-       "br-set-external-id br-ctlplane bridge-id br-ctlplane"
-      ],
-      "members": [
-       {
-        "type": "interface",
-        "name": "{{LOCAL_INTERFACE}}",
-        "primary": "true",
-        "mtu": {{LOCAL_MTU}}
-       }
-      ],
-      "addresses": [
-        {
-          "ip_netmask": "{{PUBLIC_INTERFACE_IP}}"
-        }
-      ],
-      "mtu": {{LOCAL_MTU}}
-    }
-   ]
+  {{> net_config}}
   },
   "keystone": {
     "host": "{{LOCAL_IP}}"

templates/net-config.json.template

@@ -0,0 +1,23 @@
+"network_config": [
+ {
+  "type": "ovs_bridge",
+  "name": "br-ctlplane",
+  "ovs_extra": [
+   "br-set-external-id br-ctlplane bridge-id br-ctlplane"
+  ],
+  "members": [
+   {
+    "type": "interface",
+    "name": "{{LOCAL_INTERFACE}}",
+    "primary": "true",
+    "mtu": {{LOCAL_MTU}}
+   }
+  ],
+  "addresses": [
+    {
+      "ip_netmask": "{{PUBLIC_INTERFACE_IP}}"
+    }
+  ],
+  "mtu": {{LOCAL_MTU}}
+}
+]

undercloud.conf.sample

@@ -82,6 +82,13 @@
 # what undercloud.conf provides (string value)
 #hieradata_override =
 
+# Path to network config override template. If set, this template will
+# be used to configure the networking via os-net-config. Templated
+# tags can be used within the template, see instack-
+# undercloud/elements/undercloud-stack-config/net-config.json.template
+# for example tags (string value)
+#net_config_override =
+
 # Network interface on which inspection dnsmasq will listen.  If in
 # doubt, use the default value. (string value)
 # Deprecated group/name - [DEFAULT]/discovery_interface