metrics: Make metrics actually usable

With this commit, we should get stats for the item count per event per
returned-state.

core/core/management/commands/update_metrics.py

@@ -1,8 +0,0 @@
-from django.core.management.base import BaseCommand, CommandError
-from core.metrics import update_item_count
-
-class Command(BaseCommand):
-    help = "Refresh the metrics"
-    
-    def handle(self, *args, **options):
-        update_item_count()

core/core/metrics.py

@@ -1,11 +1,35 @@
-from prometheus_client import Gauge
-from django_prometheus import exports
-from inventory.models import *
+from django.apps import apps
+from prometheus_client.core import CounterMetricFamily, REGISTRY
+from django.db.models import Case, Value, When, BooleanField, Count
+from inventory.models import Item
 
-g_items_total = Gauge('c3lf_items_total', 'Current Total items')
+class ItemCountCollector(object):
 
-def update_item_count():
-    # Get the count of MyModel objects
-    count = Item.objects.count()
-    # Set the gauge to the current count
-    g_items_total.set(count)
+    def collect(self):
+        counter = CounterMetricFamily("item_count", "Current number of items", labels=['event', 'state'])
+
+        yield counter
+
+        if not apps.models_ready or not apps.apps_ready:
+            return
+
+        queryset = (
+            Item.all_objects
+                .annotate(
+                    returned=Case(
+                        When(returned_at__isnull=False, then=Value(False)),
+                        default=Value(True),
+                        output_field=BooleanField()
+                    )
+                )
+                .values('event__slug', 'returned', 'event_id')
+                .annotate(amount=Count('id'))
+                .order_by('event__slug', 'returned')  # Optional: order by slug and returned
+        )
+
+        for e in queryset:
+            counter.add_metric([e["event__slug"].lower(), str(e["returned"])], e["amount"])
+
+        yield counter
+
+REGISTRY.register(ItemCountCollector())

core/core/settings.py

@@ -70,7 +70,6 @@ INSTALLED_APPS = [
     'inventory',
     'mail',
     'notify_sessions',
-    'core'
 ]
 
 REST_FRAMEWORK = {

deploy/ansible/playbooks/deploy-c3lf-sys3.yml

@@ -311,16 +311,6 @@
       notify:
         - restart c3lf-sys3
 
-    - name: add c3lf-sys3-cron service
-      template:
-        src: templates/c3lf-sys3-cron.service.j2
-        dest: /etc/systemd/system/c3lf-sys3-cron.service
-
-    - name: add c3lf-sys3-cron timer
-      template:
-        src: templates/c3lf-sys3-cron.timer.j2
-        dest: /etc/systemd/system/c3lf-sys3-cron.timer
-
     - name: reload systemd
       systemd:
         daemon_reload: yes
@@ -331,12 +321,6 @@
         state: started
         enabled: yes
 
-    - name: start c3lf-sys3 timer
-      service:
-        name: c3lf-sys3-cron.timer
-        state: started
-        enabled: yes
-
     - name: add postfix to www-data group
       user:
         name: postfix

deploy/ansible/playbooks/templates/c3lf-sys3-cron.service.j2

@@ -1,13 +0,0 @@
-[Unit]
-Description=c3lf sys3 background service
-After=network.target
-
-[Service]
-User=www-data
-Group=www-data
-WorkingDirectory=/var/www/c3lf-sys3
-ExecStart=/var/www/c3lf-sys3/venv/bin/python3 /var/www/c3lf-sys3/repo/core/manage.py update_metrics
-Environment=DJANGO_SETTINGS_MODULE=core.settings
-
-[Install]
-WantedBy=multi-user.target

deploy/ansible/playbooks/templates/c3lf-sys3-cron.timer.j2

@@ -1,9 +0,0 @@
-[Unit]
-Description=Run Nextcloud cron.php every 5 minutes
-
-[Timer]
-OnCalendar=minutely
-Unit=c3lf-sys3-cron.service
-
-[Install]
-WantedBy=timers.target