This is regarding allowing access to cloud monitoring probes (like google_app_engine, salesforce etc) through the proxy / firewall.
I have a VM on which I will deploying all the cloud monitoring probes. Like all other VMs, this VM also has an access to internet via proxy host, port, username and password. I tried monitoring the default instance of google_app_engine with google_app_engine probe but it displyed connection timed out. I tried specifying proxy settings through environment variable and rebooted it many times but the issue persists. So finally I decided to allow open internet for all the URLs referred by google_app_engine and other cloud monitoring probes.
Please let me know the same. Also if you happens to use google_app_engine (or any other cloud monitoring probe as an example), let me know how you have specified the proxy settings.