Fix Grafana data path for Docker stack

The default value of replicas has been decreased to 1 because
sqlite (the default database provider) doesn't work well
on shared storage.

Change-Id: I493a8cae79c080c061c5ffaf7ed463714c75226a
diff --git a/docker/swarm/stack/dashboard.yml b/docker/swarm/stack/dashboard.yml
index 934920f..d3f0391 100644
--- a/docker/swarm/stack/dashboard.yml
+++ b/docker/swarm/stack/dashboard.yml
@@ -1,11 +1,11 @@
 parameters:
   _param:
-    docker_grafana_replicas: 3
+    docker_grafana_replicas: 1
     grafana_database_type: sqlite3
     grafana_database_host: localhost
     grafana_database_port: 3306
     grafana_database_password: password
-    grafana_session_directory: /data/sessions
+    grafana_data_directory: /var/lib/grafana
     grafana_session_life_time: 86400
   docker:
     client:
@@ -21,14 +21,15 @@
               ports:
                 - 15013:3000
               volumes:
-                - /srv/glusterfs/grafana:${_param:grafana_session_directory}
+                - /srv/volumes/grafana:${_param:grafana_data_directory}
               environment:
                 GF_DATABASE_TYPE: ${_param:grafana_database_type}
                 GF_DATABASE_NAME: grafana
                 GF_DATABASE_USER: grafana
                 GF_DATABASE_PASSWORD: ${_param:grafana_database_password}
                 GF_DATABASE_HOST: "${_param:grafana_database_host}:${_param:grafana_database_port}"
+                GF_PATHS_DATA: ${_param:grafana_data_directory}
                 GF_SECURITY_ADMIN_PASSWORD: ${_param:grafana_admin_password}
                 GF_SESSION_PROVIDER: file
-                GF_SESSION_PROVIDER_CONFIG: ${_param:grafana_session_directory}
-                GF_SESSION_LIFE_TIME: ${_param:grafana_session_life_time}
+                GF_SESSION_PROVIDER_CONFIG: ${_param:grafana_data_directory}/data/sessions
+                GF_SESSION_LIFE_TIME: ${_param:grafana_session_life_time}
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