config: Use privileged decorator for set domainname action

Tests:

- Running flake8 as in .gitlab-ci.yml works.
- Setting the domain name again to update /etc/hosts file after hostname change
  works
- Setting the domain name from the text box works. New domain name is read back
  and shown properly.

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

.gitlab-ci.yml

@@ -16,7 +16,7 @@ code-quality:
   stage: test
   needs: []
   script:
-    - python3 -m flake8 --exclude actions/domainname-change,actions/networks container plinth actions/*
+    - python3 -m flake8 --exclude actions/networks container plinth actions/*
 
 unit-tests:
   stage: test

actions/domainname-change

@@ -1,21 +0,0 @@
-#!/bin/sh
-# SPDX-License-Identifier: AGPL-3.0-or-later
-
-domainname="$1"
-hostname=$(hostname)
-
-if [ -z "$domainname" ] ; then
-    if grep -q 127.0.1.1 /etc/hosts ; then
-        sed -i "s/127.0.1.1.*/127.0.1.1       $hostname/" /etc/hosts
-    else
-        sed -i "/127.0.0.1.*/a \
-            127.0.1.1        $hostname" /etc/hosts
-    fi
-else
-    if grep -q 127.0.1.1 /etc/hosts ; then
-        sed -i "s/127.0.1.1.*/127.0.1.1       $hostname.$domainname $hostname/" /etc/hosts
-    else
-        sed -i "/127.0.0.1.*/a \
-            127.0.1.1       $hostname.$domainname $hostname" /etc/hosts
-    fi
-fi

plinth/modules/config/privileged.py

@@ -4,6 +4,7 @@
 import os
 import pathlib
 import subprocess
+from typing import Optional
 
 import augeas
 
@@ -29,6 +30,32 @@ def set_hostname(hostname: str):
     action_utils.service_restart('avahi-daemon')
 
 
+@privileged
+def set_domainname(domainname: Optional[str] = None):
+    """Set system domainname in /etc/hosts."""
+    hostname = subprocess.check_output(['hostname']).decode().strip()
+    hosts_path = pathlib.Path('/etc/hosts')
+    if domainname:
+        insert_line = f'127.0.1.1 {hostname}.{domainname} {hostname}\n'
+    else:
+        insert_line = f'127.0.1.1 {hostname}\n'
+
+    lines = hosts_path.read_text(encoding='utf-8').splitlines(keepends=True)
+    new_lines = []
+    found = False
+    for line in lines:
+        if '127.0.1.1' in line:
+            new_lines.append(insert_line)
+            found = True
+        else:
+            new_lines.append(line)
+
+    if not found:
+        new_lines.append(insert_line)
+
+    hosts_path.write_text(''.join(new_lines), encoding='utf-8')
+
+
 def load_augeas():
     """Initialize Augeas."""
     aug = augeas.Augeas(flags=augeas.Augeas.NO_LOAD +

plinth/modules/config/views.py

@@ -1,14 +1,12 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
-"""
+"""FreedomBox views for basic system configuration."""
-FreedomBox views for basic system configuration.
-"""
 
 import logging
 
 from django.contrib import messages
 from django.utils.translation import gettext as _
 
-from plinth import actions, views
+from plinth import views
 from plinth.modules import config
 from plinth.signals import (domain_added, domain_removed, post_hostname_change,
                             pre_hostname_change)
@@ -21,11 +19,12 @@ LOGGER = logging.getLogger(__name__)
 
 class ConfigAppView(views.AppView):
     """Serve configuration page."""
+
     form_class = ConfigurationForm
     app_id = 'config'
 
     def get_initial(self):
-        """Return the current status"""
+        """Return the current status."""
         return {
             'hostname': config.get_hostname(),
             'domainname': config.get_domainname(),
@@ -35,7 +34,7 @@ class ConfigAppView(views.AppView):
         }
 
     def form_valid(self, form):
-        """Apply the form changes"""
+        """Apply the form changes."""
         old_status = form.initial
         new_status = form.cleaned_data
 
@@ -117,7 +116,7 @@ def set_hostname(hostname):
     privileged.set_hostname(hostname)
 
     LOGGER.info('Setting domain name after hostname change - %s', domainname)
-    actions.superuser_run('domainname-change', [domainname])
+    privileged.set_domainname(domainname)
 
     post_hostname_change.send_robust(sender='config',
                                      old_hostname=old_hostname,
@@ -125,7 +124,7 @@ def set_hostname(hostname):
 
 
 def set_domainname(domainname, old_domainname):
-    """Sets machine domain name to domainname"""
+    """Set machine domain name to domainname."""
     old_domainname = config.get_domainname()
 
     # Domain name is not case sensitive, but Let's Encrypt certificate
@@ -133,7 +132,7 @@ def set_domainname(domainname, old_domainname):
     domainname = domainname.lower()
 
     LOGGER.info('Changing domain name to - %s', domainname)
-    actions.superuser_run('domainname-change', [domainname])
+    privileged.set_domainname(domainname)
 
     # Update domain registered with Name Services module.
     if old_domainname: