Merge ~andreserl/maas:lp1787381_2.4_maas_proxy_port into maas:2.4

[Andres Rodriguez]

Backport 3d9ace9 - LP: #1787381 - Prevent the UI from re-setting proxy config settings.

[Andres Rodriguez (andreserl)]

selfie!

review: Approve

diff --git a/src/maasserver/compose_preseed.py b/src/maasserver/compose_preseed.py
index 8e5897d..f24b10f 100644
--- a/src/maasserver/compose_preseed.py
+++ b/src/maasserver/compose_preseed.py
@@ -42,6 +42,8 @@ def get_apt_proxy(rack_controller=None, default_region_ip=None):
             return http_proxy
         else:
             maas_proxy_port = Config.objects.get_config("maas_proxy_port")
+            if not maas_proxy_port:
+                maas_proxy_port = 8000
             url = "http://:%d/" % maas_proxy_port
             return compose_URL(
                 url, get_maas_facing_server_host(
diff --git a/src/maasserver/forms/__init__.py b/src/maasserver/forms/__init__.py
index 5e37481..d59b282 100644
--- a/src/maasserver/forms/__init__.py
+++ b/src/maasserver/forms/__init__.py
@@ -1477,8 +1477,17 @@ class ProxyForm(ConfigForm):
     enable_http_proxy = get_config_field('enable_http_proxy')
     use_peer_proxy = get_config_field('use_peer_proxy')
     http_proxy = get_config_field('http_proxy')
-    prefer_v4_proxy = get_config_field('prefer_v4_proxy')
-    maas_proxy_port = get_config_field('maas_proxy_port')
+    # LP: #1787381 - Fix an issue where the UI is overriding config fields
+    # that are *only* exposed over the API.
+    #
+    # XXX - since the UI for these options has been converted to Angular,
+    # MAAS no longer automatically creates fields for these based on the
+    # settings forms. As such, this form doesn't validate against the
+    # settings form (as the DNSForm would do, for example). As such
+    # .
+    # These fields need to be added back once LP: #1787467 is fixed.
+    # prefer_v4_proxy = get_config_field('prefer_v4_proxy')
+    # maas_proxy_port = get_config_field('maas_proxy_port')
 
 
 class DNSForm(ConfigForm):
diff --git a/src/maasserver/models/config.py b/src/maasserver/models/config.py
index 199e9ee..39873b7 100644
--- a/src/maasserver/models/config.py
+++ b/src/maasserver/models/config.py
@@ -182,7 +182,7 @@ class ConfigManager(Manager):
         return {
             name: configs.get(name).value
             if configs.get(name)
-            else DEFAULT_CONFIG.get(name, default)
+            else copy.deepcopy(DEFAULT_CONFIG.get(name, default))
             for name, default in zip(names, defaults)
         }