config: Allow better Apache default home page

- Don't redirect to '/index.html' when Apache Default is set as the home page.
This allows having other files such as 'index.php' as index file in
/var/www/html/.

- If the home page is currently set to 'Apache Default' upgrade the
configuration.

Tests:

- With Home page set to 'Apache Default' apply the patches. Config setup is
re-run. The configuration file becomes empty but is still present. Correctly
value is shown in the UI. /var/www/html/index.html is still shown as the home
page.

- With Home page set to 'Bepasty' apply the patches. Config setup is re-reun.
The configuration file is not modified. Bepasty is still shown as the home page.
Correctly value is shown in the UI.

- With Home page not modified apply the patches. Config setup is re-reun. The
configuration file is created. FreedomBox is the home page. Correctly value is
shown in the UI.

- On fresh machine with patches applied, perform first run. The configuration
file is not created. FreedomBox is the home page. Correctly value is shown in
the UI.

- Changing home page to Bepasty or 'Apache Default' works. Changing back to
'FreedomBox Service (Plinth)' also works.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

data/etc/apache2/conf-available/freedombox.conf

@@ -43,7 +43,9 @@
 ## into FreedomBox server.  Plinth then acts as a portal to reach all
 ## other services.
 ##
-RedirectMatch "^/$" "/plinth"
+<IfFile !/etc/apache2/conf-enabled/freedombox-apache-homepage.conf>
+    RedirectMatch "^/$" "/plinth"
+</IfFile>
 
 ##
 ## Disable sending Referer (sic) header from FreedomBox web interface to

plinth/modules/config/__init__.py

@@ -1,6 +1,8 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 """FreedomBox app for basic system configuration."""
 
+import pathlib
+
 import augeas
 from django.utils.translation import gettext_lazy as _
 
@@ -27,7 +29,7 @@ class ConfigApp(app_module.App):
 
     app_id = 'config'
 
-    _version = 5
+    _version = 6
 
     can_be_disabled = False
 
@@ -65,6 +67,12 @@ class ConfigApp(app_module.App):
         elif old_version == 4:
             privileged.set_logging_mode(privileged.get_logging_mode())
 
+        if old_version <= 5:
+            # Update the style of Apache home page redirection.
+            home_page = get_home_page()
+            if home_page == 'apache-default':
+                change_home_page(home_page)
+
         # systemd-journald is socket activated, it may not be running and it
         # does not support reload.
         service_privileged.try_restart('systemd-journald')
@@ -77,20 +85,17 @@ class ConfigApp(app_module.App):
         service_privileged.mask('rsyslog')
 
 
-def home_page_url2scid(url):
+def home_page_url2scid(url: str | None):
     """Return the shortcut ID of the given home page url."""
-    # url is None when the freedombox-apache-homepage configuration file does
-    # not exist. In this case, the default redirect in /plinth from the shipped
-    # configuration file is effective.
-    if url is None:
-        return 'plinth'
-
-    if url in ('/plinth/', '/plinth', 'plinth'):
-        return 'plinth'
-
-    if url == '/index.html':
+    # url is None when the freedombox-apache-homepage configuration file exists
+    # but is empty. In this case, no redirect is effective.
+    if url in ('/index.html', None):
         return 'apache-default'
 
+    if url in ('/plinth/', '/plinth', 'plinth', '/freedombox/', '/freedombox',
+               'freedombox'):
+        return 'plinth'
+
     if url and url.startswith('/~'):
         return 'uws-{}'.format(user_of_uws_url(url))
 
@@ -102,14 +107,12 @@ def home_page_url2scid(url):
     return None
 
 
-def _home_page_scid2url(shortcut_id):
+def _home_page_scid2url(shortcut_id: str) -> str | None:
     """Return the url for the given home page shortcut ID."""
-    if shortcut_id is None:
-        url = None
-    elif shortcut_id == 'plinth':
+    if shortcut_id == 'plinth':
         url = '/plinth/'
     elif shortcut_id == 'apache-default':
-        url = '/index.html'
+        url = None
     elif shortcut_id.startswith('uws-'):
         user = shortcut_id[4:]
         if user in get_users_with_website():
@@ -127,9 +130,12 @@ def _home_page_scid2url(shortcut_id):
     return url
 
 
-def _get_home_page_url():
+def _get_home_page_url() -> str | None:
     """Get the default application for the domain."""
     conf_file = privileged.APACHE_HOMEPAGE_CONFIG
+    if not pathlib.Path(conf_file).exists():
+        return '/plinth/'
+
     aug = augeas.Augeas(flags=augeas.Augeas.NO_LOAD +
                         augeas.Augeas.NO_MODL_AUTOLOAD)
     aug.set('/augeas/load/Httpd/lens', 'Httpd.lns')
@@ -152,14 +158,14 @@ def get_home_page():
     return home_page_url2scid(url)
 
 
-def change_home_page(shortcut_id):
+def change_home_page(shortcut_id: str):
     """Change the FreedomBox's default redirect to URL of a shortcut."""
     url = _home_page_scid2url(shortcut_id)
-    if url is None:
-        url = '/plinth/'  # fall back to default url if scid is unknown.
+    if url:
+        url = str(url)
 
     # URL may be a reverse_lazy() proxy
-    privileged.set_home_page(str(url))
+    privileged.set_home_page(url)
 
 
 def get_advanced_mode():

plinth/modules/config/privileged.py

@@ -64,12 +64,14 @@ def set_logging_mode(mode: str):
 
 
 @privileged
-def set_home_page(homepage: str):
+def set_home_page(homepage: str | None):
     """Set the default app for this FreedomBox."""
     conf_file_path = os.path.join('/etc/apache2/conf-available',
                                   APACHE_HOMEPAGE_CONF_FILE_NAME)
 
-    redirect_rule = 'RedirectMatch "^/$" "{}"\n'.format(homepage)
+    redirect_rule = ''
+    if homepage:
+        redirect_rule = 'RedirectMatch "^/$" "{}"\n'.format(homepage)
 
     with open(conf_file_path, 'w', encoding='utf-8') as conf_file:
         conf_file.write(redirect_rule)

plinth/modules/config/tests/test_config.py

@@ -17,7 +17,7 @@ from plinth.modules.config import (_home_page_scid2url, change_home_page,
 def test_homepage_mapping():
     """Basic tests for homepage functions."""
     func = home_page_url2scid
-    assert func(None) == 'plinth'
+    assert func(None) == 'apache-default'
     assert func('/unknown/url') is None
     assert func('/plinth/') == 'plinth'
     assert func('/plinth') == 'plinth'
@@ -27,9 +27,8 @@ def test_homepage_mapping():
     assert func('/~user/whatever/else') == 'uws-user'
 
     func = _home_page_scid2url
-    assert func(None) is None
     assert func('plinth') == '/plinth/'
-    assert func('apache-default') == '/index.html'
+    assert func('apache-default') is None
 
 
 def test_homepage_mapping_skip_ci():