Enable and use salt_api proxy by default

 * Use nginx as proxy
 * Misc: define defaults for
    salt_master_host
    infra_config_address
    reclass_config_master
    jenkins_salt_api_url
 * Pass certs dir for jenkins docker slaves

Related: PROD-27641(PROD:27641)
Related: PROD-30528(PROD:30528)

Change-Id: I5fac90101131a8d8d4fa7857982f18c855e0771c
diff --git a/defaults/nginx.yml b/defaults/nginx.yml
new file mode 100644
index 0000000..dd47452
--- /dev/null
+++ b/defaults/nginx.yml
@@ -0,0 +1,5 @@
+parameters:
+  _param:
+    nginx_proxy_salt_api_proxy_protocol: 'http'
+    nginx_proxy_salt_api_site_port: 8969
+    nginx_proxy_salt_api_site_protocol: 'https'