TabGroup: Make tabs pluggable via horizon plugin config

This commit enhances django tab implementation to allow horizon plugins
to add tabs to a tab group in other repository like the main horizon repo.
New setting "EXTRA_TABS" is introduced to the horizon plugin 'enabled' file.
To this aim, the tab group class looks up HORIZON_CONFIG['extra_tabs']
with its class full name and loads them as extra tabs if any.
HORIZON_CONFIG['extra_tabs'] are populated via horizon plugin settings.

This commit moves update_settings in openstack_dashboard.test.helpers
to horizon as I would like to use it in a new horizon unit test.

blueprint horizon-plugin-tab-for-info-and-quotas
Closes-Bug: #1746754
Change-Id: Ice2469a90553754929826d14d20b4719bd1f62d3

doc/source/configuration/pluggable_panels.rst

@@ -107,6 +107,51 @@ listed there will be appended to the auto-discovered files.
 
 If set to ``True``, this settings file will not be added to the settings.
 
+``EXTRA_TABS``
+--------------
+
+.. versionadded:: 14.0.0(Rocky)
+
+Extra tabs can be added to a tab group implemented in horizon or other
+horizon plugins by using this setting. Extra tabs will be shown after
+default tabs defined in a corresponding tab group.
+
+This is a dict setting. A key of the dict specifies a tab group which extra
+tab(s) are added. The key must match a full class name of the target tab group.
+
+A value of the dict is a list of full name of an extra tab classes (where a
+module name and a class name must be delimiteed by a period). Tabs specified
+via ``EXTRA_TABS`` will be displayed in the order of being registered.
+
+There might be cases where you would like to specify the order of the extra
+tabs as multiple horizon plugins can register extra tabs. You can specify a
+priority of each tab in ``EXTRA_TABS`` by using a tuple of priority and a tab
+class as an element of a dict value instead of a full name of an extra tab.
+Priority is an integer of a tab and a tab with a lower value will be displayed
+first. If a priority of an extra tab is omitted, ``0`` is assumed as a priority.
+
+Example:
+
+.. code-block:: python
+
+   EXTRA_TABS = {
+       'openstack_dashboard.dashboards.project.networks.tabs.NetworkDetailsTabs': (
+           'openstack_dashboard.dashboards.project.networks.subnets.tabs.SubnetsTab',
+           'openstack_dashboard.dashboards.project.networks.ports.tabs.PortsTab',
+       ),
+   }
+
+Example (with priority):
+
+.. code-block:: python
+
+   EXTRA_TABS = {
+       'openstack_dashboard.dashboards.project.networks.tabs.NetworkDetailsTabs': (
+           (1, 'openstack_dashboard.dashboards.project.networks.subnets.tabs.SubnetsTab'),
+           (2, 'openstack_dashboard.dashboards.project.networks.ports.tabs.PortsTab'),
+       ),
+   }
+
 ``UPDATE_HORIZON_CONFIG``
 -------------------------
 

horizon/tabs/base.py

@@ -13,16 +13,22 @@
 #    under the License.
 
 from collections import OrderedDict
+import logging
+import operator
 import sys
 
 import six
 
+from django.conf import settings
 from django.template.loader import render_to_string
 from django.template import TemplateSyntaxError
+from django.utils import module_loading
 
 from horizon import exceptions
 from horizon.utils import html
 
+LOG = logging.getLogger(__name__)
+
 SEPARATOR = "__"
 CSS_TAB_GROUP_CLASSES = ["nav", "nav-tabs", "ajax-tabs"]
 CSS_ACTIVE_TAB_CLASSES = ["active"]
@@ -36,6 +42,11 @@ class TabGroup(html.HTMLElement):
 
         The URL slug and pseudo-unique identifier for this tab group.
 
+    .. attribute:: tabs
+
+       A list of :class:`.Tab` classes. Tabs specified here are displayed
+       in the order of the list.
+
     .. attribute:: template_name
 
         The name of the template which will be used to render this tab group.
@@ -104,15 +115,55 @@ class TabGroup(html.HTMLElement):
         self.request = request
         self.kwargs = kwargs
         self._data = None
-        tab_instances = []
-        for tab in self.tabs:
-            tab_instances.append((tab.slug, tab(self, request)))
-        self._tabs = OrderedDict(tab_instances)
+        self._tabs = self._load_tabs(request)
         if self.sticky:
             self.attrs['data-sticky-tabs'] = 'sticky'
         if not self._set_active_tab():
             self.tabs_not_available()
 
+    def _load_tabs(self, request):
+        tabs = tuple(self.tabs)
+        tabs += self._load_tabs_from_config()
+        return OrderedDict([(tab.slug, tab(self, request))
+                            for tab in tabs])
+
+    def _load_tabs_from_config(self):
+        my_name = '.'.join([self.__class__.__module__,
+                            self.__class__.__name__])
+        horizon_config = settings.HORIZON_CONFIG.get('extra_tabs', {})
+        tabs_config = [self._load_tab_config(tab_config, my_name)
+                       for tab_config in horizon_config.get(my_name, [])]
+        tabs_config = [t for t in tabs_config if t]
+        tabs_config.sort(key=operator.itemgetter(0))
+        LOG.debug('Loaded extra tabs for %s: %s',
+                  my_name, tabs_config)
+        return tuple(x[1] for x in tabs_config)
+
+    @staticmethod
+    def _load_tab_config(tab_config, my_name):
+        if isinstance(tab_config, str):
+            tab_config = (0, tab_config)
+        if not isinstance(tab_config, (tuple, list)):
+            LOG.error('Extra tab definition must be a string or '
+                      'a tuple/list (tab group "%s")', my_name)
+            return
+        if len(tab_config) != 2:
+            LOG.error('Entry must be a format of (priority, tab class) '
+                      '(tab group "%s")', my_name)
+            return
+        priority, tab_class = tab_config
+        if not isinstance(priority, int):
+            LOG.error('Priority of tab entry must be an integer '
+                      '(tab group "%s")', my_name)
+            return
+        try:
+            class_ = module_loading.import_string(tab_class)
+        except ImportError:
+            LOG.error('Tab class "%s" is not found (tab group "%s")',
+                      tab_class, my_name)
+            return
+        return priority, class_
+
     def __repr__(self):
         return "<%s: %s>" % (self.__class__.__name__, self.slug)
 

horizon/test/helpers.py

@@ -16,12 +16,15 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import collections
+import copy
 import logging
 import os
 import socket
 import time
 import unittest
 
+from django.conf import settings
 from django.contrib.auth.middleware import AuthenticationMiddleware
 from django.contrib.auth.models import Permission
 from django.contrib.auth.models import User
@@ -32,6 +35,7 @@ from django.core.handlers import wsgi
 from django import http
 from django import test as django_test
 from django.test.client import RequestFactory
+from django.test import utils as django_test_utils
 from django.utils.encoding import force_text
 import six
 
@@ -331,3 +335,28 @@ class JasmineTests(SeleniumTestCase):
         if self.__class__ == JasmineTests:
             return
         self.run_jasmine()
+
+
+class update_settings(django_test_utils.override_settings):
+    """override_settings which allows override an item in dict.
+
+    django original override_settings replaces a dict completely,
+    however OpenStack dashboard setting has many dictionary configuration
+    and there are test case where we want to override only one item in
+    a dictionary and keep other items in the dictionary.
+    This version of override_settings allows this if keep_dict is True.
+
+    If keep_dict False is specified, the original behavior of
+    Django override_settings is used.
+    """
+
+    def __init__(self, keep_dict=True, **kwargs):
+        if keep_dict:
+            for key, new_value in kwargs.items():
+                value = getattr(settings, key, None)
+                if (isinstance(new_value, collections.Mapping) and
+                        isinstance(value, collections.Mapping)):
+                    copied = copy.copy(value)
+                    copied.update(new_value)
+                    kwargs[key] = copied
+        super(update_settings, self).__init__(**kwargs)

horizon/test/unit/tabs/test_tabs.py

@@ -75,6 +75,12 @@ class Group(horizon_tabs.TabGroup):
         self._assert_tabs_not_available = True
 
 
+class GroupWithConfig(horizon_tabs.TabGroup):
+    slug = "tab_group"
+    tabs = (TabOne, TabDisallowed)
+    sticky = True
+
+
 class TabWithTable(horizon_tabs.TableTab):
     table_classes = (MyTable,)
     name = "Tab With My Table"
@@ -144,6 +150,24 @@ class TabTests(test.TestCase):
         # Test get_selected_tab is None w/o GET input
         self.assertIsNone(tg.get_selected_tab())
 
+    @test.update_settings(
+        HORIZON_CONFIG={'extra_tabs': {
+            'horizon.test.unit.tabs.test_tabs.GroupWithConfig': (
+                (2, 'horizon.test.unit.tabs.test_tabs.TabDelayed'),
+                # No priority means priority 0
+                'horizon.test.unit.tabs.test_tabs.TabDisabled',
+            ),
+        }}
+    )
+    def test_tab_group_with_config(self):
+        tg = GroupWithConfig(self.request)
+        tabs = tg.get_tabs()
+        # "tab_disallowed" should NOT be in this list.
+        # Other tabs must be ordered in the priorities in HORIZON_CONFIG.
+        self.assertQuerysetEqual(tabs, ['<TabOne: tab_one>',
+                                        '<TabDisabled: tab_disabled>',
+                                        '<TabDelayed: tab_delayed>'])
+
     def test_tab_group_active_tab(self):
         tg = Group(self.request)
 

openstack_dashboard/test/helpers.py

@@ -16,8 +16,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import collections
-import copy
 from functools import wraps
 from importlib import import_module
 import logging
@@ -30,7 +28,6 @@ from django.contrib.messages.storage import default_storage
 from django.core.handlers import wsgi
 from django import http as http_request
 from django.test.client import RequestFactory
-from django.test import utils as django_test_utils
 from django import urls
 from django.utils import http
 
@@ -69,6 +66,8 @@ LOG = logging.getLogger(__name__)
 # Makes output of failing mox tests much easier to read.
 wsgi.WSGIRequest.__repr__ = lambda self: "<class 'django.http.HttpRequest'>"
 
+update_settings = horizon_helpers.update_settings
+
 
 def create_stubs(stubs_to_create=None):
     """decorator to simplify setting up multiple stubs at once via mox
@@ -754,31 +753,6 @@ class PluginTestCase(TestCase):
         base.Horizon._urls()
 
 
-class update_settings(django_test_utils.override_settings):
-    """override_settings which allows override an item in dict.
-
-    django original override_settings replaces a dict completely,
-    however OpenStack dashboard setting has many dictionary configuration
-    and there are test case where we want to override only one item in
-    a dictionary and keep other items in the dictionary.
-    This version of override_settings allows this if keep_dict is True.
-
-    If keep_dict False is specified, the original behavior of
-    Django override_settings is used.
-    """
-
-    def __init__(self, keep_dict=True, **kwargs):
-        if keep_dict:
-            for key, new_value in kwargs.items():
-                value = getattr(settings, key, None)
-                if (isinstance(new_value, collections.Mapping) and
-                        isinstance(value, collections.Mapping)):
-                    copied = copy.copy(value)
-                    copied.update(new_value)
-                    kwargs[key] = copied
-        super(update_settings, self).__init__(**kwargs)
-
-
 def mock_obj_to_dict(r):
     return mock.Mock(**{'to_dict.return_value': r})
 

openstack_dashboard/utils/settings.py

@@ -112,6 +112,7 @@ def update_dashboards(modules, horizon_config, installed_apps):
     scss_files = []
     panel_customization = []
     header_sections = []
+    extra_tabs = {}
     update_horizon_config = {}
     for key, config in import_dashboard_config(modules):
         if config.get('DISABLED', False):
@@ -154,6 +155,9 @@ def update_dashboards(modules, horizon_config, installed_apps):
         elif config.get('PANEL') or config.get('PANEL_GROUP'):
             config.pop("__builtins__", None)
             panel_customization.append(config)
+        _extra_tabs = config.get('EXTRA_TABS', {}).items()
+        for tab_key, tab_defs in _extra_tabs:
+            extra_tabs[tab_key] = extra_tabs.get(tab_key, tuple()) + tab_defs
     # Preserve the dashboard order specified in settings
     dashboards = ([d for d in config_dashboards
                    if d not in disabled_dashboards] +
@@ -169,6 +173,7 @@ def update_dashboards(modules, horizon_config, installed_apps):
     horizon_config.setdefault('js_files', []).extend(js_files)
     horizon_config.setdefault('js_spec_files', []).extend(js_spec_files)
     horizon_config.setdefault('scss_files', []).extend(scss_files)
+    horizon_config['extra_tabs'] = extra_tabs
 
     # apps contains reference to applications declared in the enabled folder
     # basically a list of applications that are internal and external plugins

releasenotes/notes/pluggable-tabs-7b7467e7c64d1e5b.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    [:bug:`1746754`]
+    (for horizon plugin developers) Django tab is now pluggable and horizon
+    plugins can add extra tab(s) to an existing tab provided by horizon or
+    other horizon plugins. Extra tabs can be added via the horizon plugin
+    "enabled" file. For more detail, see ``EXTRA_TABS`` description in
+    `Pluggable Panels and Groups <https://docs.openstack.org/horizon/latest/configuration/pluggable_panels.html#extra-tabs>`__
+    of the horizon documentation.