Add an optional environment variable for docker images in order to easily and globally configure additional startup flags

[abdallahghdiri]

Why is this needed

Web apps using the Web Crypto API will only work in Secure contexts (HTTPS) (or for web apps served over localhost or .localhost domain)

The latest Keycloak release (26) began using this API in its Javascript adapter for example

How to bypass this limitation

In order to bypass this limitation and facilitate local testing using karate UI, we can add the following flag --unsafely-treat-insecure-origin-as-secure to chromium based browsers in karate docker images

Proposal

Add an optional environment variable in karate docker images that when set add its value as additional flags to browsers' startup command.

  karate-additional-browser-flags:
    image: karatelabs/karate-chrome:latest
    environment:
      KARATE_BROWSER_ADDITIONAL_FLAGS: "--unsafely-treat-insecure-origin-as-secure=http://keycloak:8080"

Using a generic environment variable should offer flexibility to adapt the images in future use cases