The problem

The pipe character does not seem to work in Istio's VirtualService.

The example below is intended to route requests based on the user-agent header. Requests from a mobile device should go to myapp and requests from a desktop user should go to deskt-app, handled by next match block. The <REGEX> field works when I use this regex:

• ^.*\bMobile\b.*$

But the powers that be require a more sophisticated regex to identify mobile users. My routing breaks entirely when I use these:

• ^.*\b(iPhone|Pixel)\b.*$
• ^.*\b(iPhone|Pixel)+\b.*$
• ^.*\biPhone|Pixel\b.*$

Expected behavior

Using a regex with a pipe (logical OR) I expect to be routed to myapp when I have a user-agent header that contains the word "iPhone" or "Pixel".

Actual behavior

I get routed to deskt-app.

The question

How do I achieve a logical OR in an Istio VirtualService regex pattern? And is that my problem or am I overlooking something obvious?

Example VirtualService

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
  ...
  ...
  http:
  - match:
    - headers:
        user-agent:
          regex: "<REGEX>"    <------
      uri:
        prefix: /foo/bar
    route:
    - destination:
        host: myapp
        port:
          number: 80
  - match:
    - uri:
        prefix: /foo/bar
    route:
    - destination:
        host: deskt-app
        port:
          number: 80

EDIT: Github Issue