Frontend OTel: read meta otlp-endpoint; set endpoint in Conduit index.html to API proxy for Aspire

Author: Maurice Peters

Abies.Conduit/wwwroot/index.html

@@ -7,6 +7,8 @@
     <base href="/">
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <!-- Aspire: point browser OTLP exporter to API proxy to avoid CORS -->
+    <meta name="otlp-endpoint" content="http://localhost:5179/otlp/v1/traces">
     <!-- Local Conduit CSS to avoid CORS errors -->
     <link rel="stylesheet" href="css/main.css" />
     <link href="https://code.ionicframework.com/ionicons/2.0.1/css/ionicons.min.css" rel="stylesheet" type="text/css" crossorigin="anonymous">

Abies/wwwroot/abies.js

@@ -35,6 +35,12 @@ void (async () => {
       const guessOtlp = () => {
         // Allow explicit global override
         if (window.__OTLP_ENDPOINT) return window.__OTLP_ENDPOINT;
+        // Allow per-app meta override: <meta name="otlp-endpoint" content="https://collector:4318/v1/traces">
+        try {
+          const meta = document.querySelector('meta[name="otlp-endpoint"]');
+          const v = meta && meta.getAttribute('content');
+          if (v) return v;
+        } catch {}
         // Prefer a same-origin proxy to avoid CORS issues with collectors
         try { return new URL('/otlp/v1/traces', window.location.origin).href; } catch {}
         // Fallback to common local collector endpoints