Pass secrets to containers as files instead of env variables

Related-Prod: PROD-34268
Change-Id: I8269e2c3f0402980df13430de213764a7e2f8949
diff --git a/docker/swarm/stack/monitoring/alerta.yml b/docker/swarm/stack/monitoring/alerta.yml
index acd4d70..ac16a2b 100644
--- a/docker/swarm/stack/monitoring/alerta.yml
+++ b/docker/swarm/stack/monitoring/alerta.yml
@@ -8,6 +8,7 @@
     client:
       stack:
         monitoring:
+          version: '3.7'
           service:
             alerta:
               networks:
@@ -27,6 +28,13 @@
                 - ${prometheus:alerta:config_dir}/alertad.conf:/app/alertad.conf
               environment:
                 ADMIN_USERS: ${_param:alerta_admin_username}
-                ADMIN_PASSWORD: ${_param:alerta_admin_password}
+                ADMIN_PASSWORD_FILE: "/run/secrets/alerta"
                 MONGO_URI: ${_param:alerta_mongodb_uri}
                 PLUGINS: ""
+              secrets:
+                - alerta
+          secrets:
+            alerta:
+              external: true
+              value: ${_param:alerta_admin_password}
+