feat(k8s/firefly): add Firefly III with PostgreSQL and backups

kubernetes/app/firefly/service-db.yaml

@@ -0,0 +1,12 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: firefly-db
+  namespace: firefly
+spec:
+  clusterIP: None
+  selector:
+    app: firefly-db
+  ports:
+    - port: 5432
+      targetPort: 5432