setup: Disable install/upgrade when dpkg/apt is running

Show a warning message that a package manager is running. This prevents users
from getting an installation error just because another installation/upgrade is
running.

Closes: #625.

actions/packages

@@ -28,6 +28,8 @@ import sys
 
 from plinth import cfg
 
+LOCK_FILE = '/var/lib/dpkg/lock'
+
 
 def parse_arguments():
     """Return parsed command line arguments as dictionary."""
@@ -41,6 +43,8 @@ def parse_arguments():
         'module', help='name of module for which package is being installed')
     subparser.add_argument(
         'packages', nargs='+', help='list of packages to install')
+    subparsers.add_parser('is-package-manager-busy',
+                          help='Return whether package manager is busy')
 
     subparsers.required = True
     return parser.parse_args()
@@ -94,6 +98,14 @@ def _assert_managed_packages(module, packages):
         assert package in module.managed_packages
 
 
+def subcommand_is_package_manager_busy(_):
+    """Return whether package manager is busy."""
+    try:
+        subprocess.check_output(['lsof', LOCK_FILE])
+    except subprocess.CalledProcessError:
+        sys.exit(-1)
+
+
 def main():
     """Parse arguments and perform all duties."""
     arguments = parse_arguments()

actions/upgrades

@@ -28,7 +28,6 @@ import sys
 
 CONF_FILE = '/etc/apt/apt.conf.d/50unattended-upgrades'
 AUTO_CONF_FILE = '/etc/apt/apt.conf.d/20auto-upgrades'
-LOCK_FILE = '/var/lib/dpkg/lock'
 LOG_FILE = '/var/log/unattended-upgrades/unattended-upgrades.log'
 
 
@@ -42,8 +41,6 @@ def parse_arguments():
                           help='Check if automatic upgrades are enabled')
     subparsers.add_parser('enable-auto', help='Enable automatic upgrades')
     subparsers.add_parser('disable-auto', help='Disable automatic upgrades.')
-    subparsers.add_parser('is-package-manager-busy',
-                          help='Return whether package manager is busy')
     subparsers.add_parser('get-log', help='Print the automatic upgrades log')
 
     subparsers.required = True
@@ -129,14 +126,6 @@ def setup():
                 conffile.write('        "origin=Debian";\n')
 
 
-def subcommand_is_package_manager_busy(_):
-    """Return whether package manager is busy."""
-    try:
-        subprocess.check_output(['lsof', LOCK_FILE])
-    except subprocess.CalledProcessError:
-        sys.exit(-1)
-
-
 def subcommand_get_log(_):
     """Print the automatic upgrades log."""
     try:

plinth/modules/upgrades/views.py

@@ -84,11 +84,10 @@ class UpgradesConfigurationView(FormView):
         return super().form_valid(form)
 
 
-
 def is_package_manager_busy():
     """Return whether a package manager is running."""
     try:
-        actions.superuser_run('upgrades', ['is-package-manager-busy'])
+        actions.superuser_run('packages', ['is-package-manager-busy'])
         return True
     except actions.ActionError:
         return False

plinth/templates/setup.html

@@ -50,8 +50,19 @@
       <form action="" method="post">
         {% csrf_token %}
 
-        <input type="submit" class="btn btn-md btn-primary"
-               value="{% trans "Install" %}" />
+        {% if package_manager_is_busy %}
+          <div class="alert alert-warning" role="alert">
+            {% blocktrans trimmed %}
+              Another installation or upgrade is already running.
+              Please wait for a few moments before trying again.
+            {% endblocktrans %}
+          </div>
+          <input type="submit" class="btn btn-md btn-primary"
+                 disabled="disabled" value="{% trans "Install" %}" />
+        {% else %}
+          <input type="submit" class="btn btn-md btn-primary"
+                 value="{% trans "Install" %}" />
+        {% endif %}
       </form>
     {% elif setup_helper.get_state == 'needs-update' %}
       <p>
@@ -63,8 +74,19 @@
       <form action="" method="post">
         {% csrf_token %}
 
-        <input type="submit" class="btn btn-md btn-primary"
-               value="{% trans "Update" %}" />
+        {% if package_manager_is_busy %}
+          <div class="alert alert-warning" role="alert">
+            {% blocktrans trimmed %}
+              Another installation or upgrade is already running.
+              Please wait for a few moments before trying again.
+            {% endblocktrans %}
+          </div>
+          <input type="submit" class="btn btn-md btn-primary"
+                 disabled="disabled" value="{% trans "Install" %}" />
+        {% else %}
+          <input type="submit" class="btn btn-md btn-primary"
+                 value="{% trans "Update" %}" />
+        {% endif %}
       </form>
     {% endif %}
 

plinth/views.py

@@ -30,6 +30,7 @@ import time
 
 from . import forms, frontpage
 import plinth
+from plinth import actions
 
 
 @public
@@ -208,8 +209,17 @@ class SetupView(TemplateView):
         """Return the context data rendering the template."""
         context = super(SetupView, self).get_context_data(**kwargs)
         context['setup_helper'] = self.kwargs['setup_helper']
+        context['package_manager_is_busy'] = self.is_package_manager_busy()
         return context
 
+    def is_package_manager_busy(self):
+        """Return whether a package manager is running."""
+        try:
+            actions.superuser_run('packages', ['is-package-manager-busy'])
+            return True
+        except actions.ActionError:
+            return False
+
     def post(self, *args, **kwargs):
         """Handle installing/upgrading applications.