diagnostics: Store results of full run in database

Tests:

- Run diagnostics. Restart plinth, and check that the diagnostics results are
  still available to view.

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

plinth/modules/diagnostics/__init__.py

@@ -4,22 +4,24 @@ FreedomBox app for system diagnostics.
 """
 
 import collections
+import json
 import logging
 import pathlib
 import threading
+from copy import deepcopy
 
 import psutil
 from django.utils.translation import gettext_lazy as _
 from django.utils.translation import gettext_noop
 
 from plinth import app as app_module
-from plinth import daemon, glib, menu
+from plinth import daemon, glib, kvstore, menu
 from plinth import operation as operation_module
 from plinth.modules.apache.components import diagnose_url_on_all
 from plinth.modules.backups.components import BackupRestore
 
 from . import manifest
-from .check import Result
+from .check import CheckJSONDecoder, CheckJSONEncoder, Result, translate_checks
 
 _description = [
     _('The system diagnostic test will run a number of checks on your '
@@ -117,8 +119,7 @@ def _run_on_all_enabled_modules():
                 continue
 
             apps.append((app.app_id, app))
-            app_name = app.info.name or app.app_id
-            current_results['results'][app.app_id] = {'name': app_name}
+            current_results['results'][app.app_id] = {'id': app.app_id}
 
         current_results['apps'] = apps
 
@@ -266,6 +267,9 @@ def _run_diagnostics():
     _run_on_all_enabled_modules()
     with results_lock:
         results = current_results['results']
+        # Store the most recent results in the database.
+        kvstore.set('diagnostics_results',
+                    json.dumps(results, cls=CheckJSONEncoder))
 
     issue_count = 0
     severity = 'warning'
@@ -309,3 +313,39 @@ def _run_diagnostics():
                                          message=message, actions=actions,
                                          data=data, group='admin')
     note.dismiss(False)
+
+
+def are_results_available():
+    """Return whether diagnostic results are available."""
+    with results_lock:
+        results = current_results
+
+    if not results:
+        results = kvstore.get_default('diagnostics_results', '{}')
+        results = json.loads(results)
+
+    return bool(results)
+
+
+def get_results():
+    """Return the latest results of full diagnostics."""
+    with results_lock:
+        results = deepcopy(current_results)
+
+    # If no results are available in memory, then load from database.
+    if not results:
+        results = kvstore.get_default('diagnostics_results', '{}')
+        results = json.loads(results, cls=CheckJSONDecoder)
+        results = {'results': results, 'progress_percentage': 100}
+
+    # Translate and format diagnostic check descriptions for each app
+    for app_id in results['results']:
+        app = app_module.App.get(app_id)
+        app_name = app.info.name or app_id
+        results['results'][app_id]['name'] = app_name
+        if 'diagnosis' in results['results'][app_id]:
+            diagnosis = results['results'][app_id]['diagnosis']
+            results['results'][app_id]['diagnosis'] = translate_checks(
+                diagnosis)
+
+    return results

plinth/modules/diagnostics/check.py

@@ -1,8 +1,10 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 """Diagnostic check data type."""
 
+import dataclasses
 from dataclasses import dataclass, field
 from enum import StrEnum
+import json
 
 from django.utils.translation import gettext
 
@@ -18,9 +20,6 @@ class Result(StrEnum):
     ERROR = 'error'
 
 
-# TODO: Description should not be translated until we need to display it.
-
-
 @dataclass
 class DiagnosticCheck:
     """A diagnostic check and optional result and parameters."""
@@ -44,3 +43,32 @@ def translate(check: DiagnosticCheck) -> DiagnosticCheck:
 def translate_checks(checks: list[DiagnosticCheck]) -> list[DiagnosticCheck]:
     """Translate and format diagnostic checks."""
     return [translate(check) for check in checks]
+
+
+class CheckJSONEncoder(json.JSONEncoder):
+    """Encode objects that include DiagnosticChecks."""
+
+    def default(self, o):
+        """Add class tag to DiagnosticChecks."""
+        if isinstance(o, DiagnosticCheck):
+            o = dataclasses.asdict(o)
+            o.update({'__class__': 'DiagnosticCheck'})
+            return o
+
+        return super().default(o)
+
+
+class CheckJSONDecoder(json.JSONDecoder):
+    """Decode objects that include DiagnosticChecks."""
+
+    def __init__(self):
+        json.JSONDecoder.__init__(self, object_hook=CheckJSONDecoder.from_dict)
+
+    @staticmethod
+    def from_dict(data):
+        """Convert tagged data to DiagnosticCheck."""
+        if data.get('__class__') == 'DiagnosticCheck':
+            return DiagnosticCheck(data['check_id'], data['description'],
+                                   data['result'], data['parameters'])
+
+        return data

plinth/modules/diagnostics/templates/diagnostics.html

@@ -16,7 +16,7 @@
              value="{% trans "Run Diagnostics" %}"/>
     </form>
 
-    {% if results %}
+    {% if results_available %}
       <a class="btn btn-default" role="button"href="{% url 'diagnostics:full' %}">
         {% trans "View Results" %}
       </a>

plinth/modules/diagnostics/tests/test_check.py

@@ -1,9 +1,13 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for diagnostic check data type."""
 
+import json
 import pytest
 
-from plinth.modules.diagnostics.check import DiagnosticCheck, Result, translate
+from plinth.modules.diagnostics.check import (DiagnosticCheck,
+                                              CheckJSONEncoder,
+                                              CheckJSONDecoder, Result,
+                                              translate)
 
 
 def test_result():
@@ -57,3 +61,18 @@ def test_translate():
                             Result.PASSED, {'key': 'value'})
     translated = translate(check)
     assert translated.description == 'sample check ?missing?'
+
+
+def test_json_encoder_decoder():
+    """Test encoding and decoding as JSON."""
+    check = DiagnosticCheck('some-check-id', 'sample check', Result.PASSED)
+    check_json = json.dumps(check, cls=CheckJSONEncoder)
+    for string in [
+            '"check_id": "some-check-id"', '"description": "sample check"',
+            '"result": "passed"', '"parameters": {}',
+            '"__class__": "DiagnosticCheck"'
+    ]:
+        assert string in check_json
+
+    decoded_check = json.loads(check_json, cls=CheckJSONDecoder)
+    assert decoded_check == check

plinth/modules/diagnostics/views.py

@@ -3,7 +3,6 @@
 FreedomBox app for running diagnostics.
 """
 
-from copy import deepcopy
 import logging
 
 from django.http import Http404, HttpResponseRedirect
@@ -36,12 +35,9 @@ class DiagnosticsView(AppView):
 
     def get_context_data(self, **kwargs):
         """Return additional context for rendering the template."""
-        with diagnostics.results_lock:
-            results = diagnostics.current_results
-
         context = super().get_context_data(**kwargs)
         context['has_diagnostics'] = False
-        context['results'] = results
+        context['results_available'] = diagnostics.are_results_available()
         return context
 
 
@@ -62,19 +58,9 @@ class DiagnosticsFullView(TemplateView):
         except KeyError:
             is_task_running = False
 
-        with diagnostics.results_lock:
-            results = deepcopy(diagnostics.current_results)
-
-        # Translate and format diagnostic check descriptions for each app
-        for app_id in results['results']:
-            if 'diagnosis' in results['results'][app_id]:
-                diagnosis = results['results'][app_id]['diagnosis']
-                results['results'][app_id]['diagnosis'] = translate_checks(
-                    diagnosis)
-
         context = super().get_context_data(**kwargs)
         context['is_task_running'] = is_task_running
-        context['results'] = results
+        context['results'] = diagnostics.get_results()
         context['refresh_page_sec'] = 3 if is_task_running else None
         return context