fix(computes): overview state comes from the connection

The overview page decided whether the host is up with a TCP probe of
the compute's hostname. For an ssh compute named by an ssh_config alias
or reached through ProxyJump, that name and port cannot be reached from
WebVirtCloud directly, so the probe failed while the connection worked:
the page showed the host details and never started the CPU and memory
graphs. The overview now uses Compute.status, the connection
WebVirtCloud uses for everything else.

The compute list shows why a host is not connected (Compute.connection_error)
under "Not Connected", for example a host key verification failure.

Checked against the ssh compute of the test setup through an
ssh_config alias: the previous code renders the overview with the
graphs off, the new one with them on. Both new tests fail on the
previous code.

computes/templates/computes/list.html

@@ -37,7 +37,9 @@
                             {{ compute.name }}
                         </td>
                         <td class="col-sm-2">
-                            {% if compute.status is True %}{% trans "Connected" %}{% else %}{% trans "Not Connected" %}{% endif %}
+                            {% if compute.status is True %}{% trans "Connected" %}{% else %}{% trans "Not Connected" %}
+                                <br><small class="text-danger">{{ compute.connection_error }}</small>
+                            {% endif %}
                         </td>
                         <td class="col-sm-5">
                             {{ compute.details|default:"" }}

computes/test_overview_status.py

@@ -0,0 +1,37 @@
+from unittest.mock import PropertyMock, patch
+
+from django.contrib.auth import get_user_model
+from django.test import TestCase
+from django.urls import reverse
+
+from computes.models import Compute
+
+ERROR = "Connection Failed: Host key verification failed."
+
+
+class OverviewStatusTests(TestCase):
+    def setUp(self):
+        self.client.force_login(
+            get_user_model().objects.create_superuser(username="ov-admin", password="pwd", email="ov@example.com")
+        )
+        # an ssh_config alias: not a name a TCP probe can reach
+        self.compute = Compute.objects.create(name="ov-alias", hostname="wvc-alias", login="root", password="", type=2)
+
+    @patch("vrtManager.connection.connection_manager.host_is_up", return_value=False)
+    @patch("computes.views.wvmHostDetails")
+    def test_overview_state_comes_from_the_connection(self, host_details, host_is_up):
+        conn = host_details.return_value
+        conn.get_node_info.return_value = ("host", "x86_64", 1024, 2, "cpu", "qemu+ssh://root@wvc-alias/system")
+        conn.get_memory_usage.return_value = {"total": 1024, "usage": 512, "percent": 50}
+        with patch.object(Compute, "status", new_callable=PropertyMock, return_value=True):
+            response = self.client.get(reverse("overview", args=[self.compute.id]))
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.context["status"], "true")
+
+    def test_compute_list_shows_why_a_host_is_not_connected(self):
+        with patch.object(Compute, "status", new_callable=PropertyMock, return_value=False), patch.object(
+            Compute, "connection_error", new_callable=PropertyMock, return_value=ERROR
+        ):
+            response = self.client.get(reverse("computes"))
+        self.assertContains(response, "Not Connected")
+        self.assertContains(response, ERROR)

computes/views.py

@@ -7,10 +7,7 @@ from django.urls import reverse
 from django.utils import timezone
 from instances.models import Instance
 from libvirt import libvirtError
-from vrtManager.connection import (
-    connection_manager,
-    wvmConnect,
-)
+from vrtManager.connection import wvmConnect
 from vrtManager.hostdetails import wvmHostDetails
 
 from computes.forms import (
@@ -39,11 +36,9 @@ def computes(request):
 @superuser_only
 def overview(request, compute_id):
     compute = get_object_or_404(Compute, pk=compute_id)
-    status = (
-        "true"
-        if connection_manager.host_is_up(compute.type, compute.hostname) is True
-        else "false"
-    )
+    # the connection itself, not a TCP probe: ssh aliases and ProxyJump hosts
+    # are not reachable by name and port from here
+    status = "true" if compute.status else "false"
 
     conn = wvmHostDetails(
         compute.hostname,