Region-Tagging Your App: Letting App Service Tell You Where It's Running

Here's a small but high-value pattern: surface the running region in the UI footer. During a Front Door failover drill, you can see in the browser that you're now hitting Korea, not Sweden.

The three-line implementation

APP_REGION = (
    os.getenv("APP_REGION")        # explicit override
    or os.getenv("REGION_NAME")    # App Service auto-injects this
    or "local"
)

App Service automatically sets REGION_NAME to the friendly region string (e.g. Sweden Central). You don't have to configure it. It Just Works on every App Service in every region.

Show it in the UI

Pass app_region through a Flask context processor; render it in your base layout footer:

<span class="region-badge">
  <span class="region-dot"></span>Region: {{ app_region }}
</span>

Add a green pulsing dot via CSS keyframes (and respect prefers-reduced-motion — accessibility matters even on a portfolio site).

The payoff is bigger than it looks. During a drill, instead of trusting abstract dashboards, you and your team watch the badge flip from swedencentral to koreacentral. Visible failover builds confidence — and confidence is what DR programs actually deliver.