title: How do I secure a Google cloud function being used as the host for a Diaglogflow / Google Action
body: <p>I have a voice application with Dialogflow, google actions, and the code is hosted on a cloud function. The function, Dialogflow and the action all belong to the same google project, and the function is set up as an HTTP trigger. 
  Everything works but my problem is securing the function. The default ingress setting for the HTTP triggered functions is to allow all traffic, but I changed it to "Allow internal traffic only". I don't have a VPC connector set up, but the description of this ingress rule states: "Only traffic from within the same project or the same VPC SC perimeter is allowed". Since the DialogFlow agent and the action all belong to the same project, I would expect it to be able to reach that function without issue. However, with that ingress setting turned on the Action runs into an error when I test in the simulator and when traffic is set to allow all it works. I'm leaving it to internal only because I don't want it open to the world, but I will need to host on my GCF when I want to publish. 
  Googling around I don't see much documentation other than how to set up IAM users and rules to be able to access and update the function itself, but I can't find anything on rules to apply when triggering the function. 
  I'm fairly new to google cloud, I'm sure this has an easy fix, but I just can't find the right answers. </p>