apache: Reload apache using component if config changes

We often change apache configuration for an app and when a new version of the
config is deployed the changes go un-applied until FreedomBox is restarted. Allow
specifying that config has changed in an particular version and reload of
configuration is needed.

Tests:

- Unit tests pass. The feature used in transmission works.

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

plinth/modules/apache/components.py

@@ -8,6 +8,7 @@ from django.utils.text import format_lazy
 from django.utils.translation import gettext_lazy
 
 from plinth import action_utils, app
+from plinth.privileged import service as service_privileged
 
 from . import privileged
 
@@ -16,7 +17,7 @@ class Webserver(app.LeaderComponent):
     """Component to enable/disable Apache configuration."""
 
     def __init__(self, component_id, web_name, kind='config', urls=None,
-                 expect_redirects=False):
+                 expect_redirects=False, last_updated_version=None):
         """Initialize the web server component.
 
         component_id should be a unique ID across all components of an app and
@@ -33,6 +34,9 @@ class Webserver(app.LeaderComponent):
         urls is a list of URLs over which a HTTP services will be available due
         to this component. This list is only used for running diagnostics.
 
+        last_updated_version is the app version in which the web server
+        configuration/site/module file was updated. Using this, web server will
+        be automatically reloaded or restarted as necessary during app upgrade.
         """
         super().__init__(component_id)
 
@@ -40,6 +44,7 @@ class Webserver(app.LeaderComponent):
         self.kind = kind
         self.urls = urls or []
         self.expect_redirects = expect_redirects
+        self.last_updated_version = last_updated_version
 
     def is_enabled(self):
         """Return whether the Apache configuration is enabled."""
@@ -71,6 +76,28 @@ class Webserver(app.LeaderComponent):
 
         return results
 
+    def setup(self, old_version):
+        """Restart/reload web server if configuration files changed."""
+        if not old_version:
+            # App is being freshly setup. After setup, app will be enabled
+            # which will result in reload/restart of web server.
+            return
+
+        if old_version >= self.last_updated_version:
+            # Already using the latest configuration. Web server reload/restart
+            # is not necessary.
+            return
+
+        if not self.app.is_enabled():
+            # App is currently disabled, web server will reloaded/restarted
+            # when the app is enabled.
+            return
+
+        if self.kind == 'module':
+            service_privileged.restart('apache2')
+        else:
+            service_privileged.reload('apache2')
+
 
 class Uwsgi(app.LeaderComponent):
     """Component to enable/disable uWSGI configuration."""

plinth/modules/apache/tests/test_components.py

@@ -8,6 +8,7 @@ from unittest.mock import call, patch
 
 import pytest
 
+from plinth import app
 from plinth.modules.apache.components import (Uwsgi, Webserver, check_url,
                                               diagnose_url,
                                               diagnose_url_on_all)
@@ -95,6 +96,51 @@ def test_webserver_diagnose(diagnose_url_on_all, diagnose_url):
         [call('{host}url1', check_certificate=False, expect_redirects=False)])
 
 
+@patch('plinth.privileged.service.restart')
+@patch('plinth.privileged.service.reload')
+def test_webserver_setup(service_reload, service_restart):
+    """Test that component restart/reloads web server during app upgrades."""
+
+    class AppTest(app.App):
+        app_id = 'testapp'
+        enabled = False
+
+        def is_enabled(self):
+            return self.enabled
+
+    app1 = AppTest()
+    webserver1 = Webserver('test-webserver1', 'test-config',
+                           last_updated_version=5)
+    for version in (0, 5, 6):
+        webserver1.setup(old_version=version)
+        service_reload.assert_not_called()
+        service_restart.assert_not_called()
+
+    app1.enabled = False
+    webserver2 = Webserver('test-webserver2', 'test-config',
+                           last_updated_version=5)
+    app1.add(webserver2)
+    webserver2.setup(old_version=3)
+    service_reload.assert_not_called()
+    service_restart.assert_not_called()
+
+    app1.enabled = True
+    webserver3 = Webserver('test-webserver3', 'test-config',
+                           last_updated_version=5)
+    app1.add(webserver3)
+    webserver3.setup(old_version=3)
+    service_reload.assert_has_calls([call('apache2')])
+    service_restart.assert_not_called()
+    service_reload.reset_mock()
+
+    webserver4 = Webserver('test-webserver', 'test-module', 'module',
+                           last_updated_version=5)
+    app1.add(webserver4)
+    webserver4.setup(old_version=3)
+    service_restart.assert_has_calls([call('apache2')])
+    service_reload.assert_not_called()
+
+
 def test_uwsgi_init():
     """Test that uWSGI component can be initialized."""
     with pytest.raises(ValueError):