force isolated timeout settings to be positive integers

see: https://github.com/ansible/ansible-tower/issues/7328

awx/main/conf.py

@@ -175,6 +175,7 @@ register(
 register(
     'AWX_ISOLATED_CHECK_INTERVAL',
     field_class=fields.IntegerField,
+    min_value=0,
     label=_('Isolated status check interval'),
     help_text=_('The number of seconds to sleep between status checks for jobs running on isolated instances.'),
     category=_('Jobs'),
@@ -184,6 +185,7 @@ register(
 register(
     'AWX_ISOLATED_LAUNCH_TIMEOUT',
     field_class=fields.IntegerField,
+    min_value=0,
     label=_('Isolated launch timeout'),
     help_text=_('The timeout (in seconds) for launching jobs on isolated instances.  '
                 'This includes the time needed to copy source control files (playbooks) to the isolated instance.'),
@@ -194,6 +196,7 @@ register(
 register(
     'AWX_ISOLATED_CONNECTION_TIMEOUT',
     field_class=fields.IntegerField,
+    min_value=0,
     default=10,
     label=_('Isolated connection timeout'),
     help_text=_('Ansible SSH connection timeout (in seconds) to use when communicating with isolated instances. '

awx/main/tests/functional/api/test_settings.py

@@ -243,3 +243,19 @@ def test_logging_aggregrator_connection_test_invalid(mocker, get, post, admin):
             'LOG_AGGREGATOR_PORT': 8080
         }, user=admin, expect=500)
         assert resp.data == {'error': '404: Not Found'}
+
+
+@pytest.mark.django_db
+@pytest.mark.parametrize('setting_name', [
+    'AWX_ISOLATED_CHECK_INTERVAL',
+    'AWX_ISOLATED_LAUNCH_TIMEOUT',
+    'AWX_ISOLATED_CONNECTION_TIMEOUT',
+])
+def test_isolated_job_setting_validation(get, patch, admin, setting_name):
+    url = reverse('api:setting_singleton_detail', kwargs={'category_slug': 'jobs'})
+    patch(url, user=admin, data={
+        setting_name: -1
+    }, expect=400)
+
+    data = get(url, user=admin).data
+    assert data[setting_name] != -1