VirtualService HTTPMatchRequest.regex breaks when using pipes

[mehemken]

Describe the bug

As seen on StackOverflow.

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.

Steps to reproduce the bug

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

Version

K8s
kubectl Client: 1.9.9
kubectl Server: 1.10.9-gke.5

Istio
Version: 1.0.5
GitRevision: c1707e4
User: root@6f6ea1061f2b
Hub: docker.io/istio
GolangVersion: go1.10.4
BuildStatus: Clean

Installation
With the Helm chart.

Environment
GKE

[mehemken]

This is superficially similar to #10666 , however, my application is in fact sending the user-agent header.

[mehemken]

The Stackoverflow question got answered. I will try the change in regex and report if it works or not.

[mehemken]

Unfortunately the project was nixed before I could verify the Stackoverflow answer.