Add prometheus, alertmanager, pushgateway configs

Change-Id: I7f146e0207ada58f0723b14d0a625a6bce67ea9f
diff --git a/metadata/service/pushgateway/container.yml b/metadata/service/pushgateway/container.yml
new file mode 100644
index 0000000..28c24e6
--- /dev/null
+++ b/metadata/service/pushgateway/container.yml
@@ -0,0 +1,6 @@
+applications:
+  - pushgateway
+parameters:
+  prometheus:
+    pushgateway:
+      enabled: true