Add HTTPS proxy for Prometheus and Alertmanager

Change-Id: I57a04c716290891cfc0fe32a23a09d6c2843b837
Closes-bug: PROD-20150
diff --git a/docker/swarm/stack/monitoring/prometheus/init.yml b/docker/swarm/stack/monitoring/prometheus/init.yml
index 2d455f7..65dd5b9 100644
--- a/docker/swarm/stack/monitoring/prometheus/init.yml
+++ b/docker/swarm/stack/monitoring/prometheus/init.yml
@@ -38,7 +38,7 @@
                 PROMETHEUS_BIND_PORT: ${prometheus:server:bind:port}
                 PROMETHEUS_BIND_ADDRESS: ${prometheus:server:bind:address}
                 PROMETHEUS_STORAGE_LOCAL_RETENTION: ${prometheus:server:storage:local:retention}
-                PROMETHEUS_EXTERNAL_URL: "http://${_param:stacklight_monitor_address}:15010"
+                PROMETHEUS_EXTERNAL_URL: "https://${_param:stacklight_monitor_address}:15010"
                 # Backward compatibility for Prometheus 1.7
                 PROMETHEUS_STORAGE_LOCAL_ENGINE: ${_param:prometheus_storage_local_engine}
                 PROMETHEUS_STORAGE_LOCAL_TARGET_HEAP_SIZE: ${_param:prometheus_storage_heap_size}