feat: add support for external Prometheus URLs

Signed-off-by: Tusharjamdade <tusharnjamdade@gmail.com>

Author: Tusharjamdade

prometheus/src/components/Settings/Settings.tsx

@@ -14,18 +14,12 @@ import { useEffect, useState } from 'react';
 import { isHttpUrl } from '../../util';
 
 /**
- * Validates if the given address string is in a supported format.
+ * Validates whether the given address is in a supported format.
+ * Supports namespace/service:port and HTTP/HTTPS URLs.
+ * Examples: monitoring/prometheus:9090, https://prometheus.example.com
  *
- * Supported formats:
- *  - Kubernetes Service address: namespace/service-name:port
- *    Example: monitoring/prometheus:9090
- *
- *  - HTTP or HTTPS URL:
- *    Example: https://prometheus.example.com
- *    Example: http://mimir.company.net:9009
- *
- * @param {string} address - The address string to validate.
- * @returns {boolean} True if the address is valid, false otherwise.
+ * @param address - The address string to validate.
+ * @returns True if the address is valid, false otherwise.
  */
 function isValidAddress(address: string): boolean {
   if (!address) return true;

prometheus/src/request.tsx

@@ -298,58 +298,68 @@ export async function fetchMetrics(data: {
   subPath?: string;
 }): Promise<object> {
   const params = new URLSearchParams();
-  if (data.from) params.append('start', data.from.toString());
-  if (data.to) params.append('end', data.to.toString());
-  if (data.step) params.append('step', data.step.toString());
-  if (data.query) params.append('query', data.query);
+  if (data.from) {
+    params.append('start', data.from.toString());
+  }
+  if (data.to) {
+    params.append('end', data.to.toString());
+  }
+  if (data.step) {
+    params.append('step', data.step.toString());
+  }
+  if (data.query) {
+    params.append('query', data.query);
+  }
 
   const isExternal = isHttpUrl(data.prefix);
-  let url: string;
+  var url: string;
 
-  // 1. Construct the URL based on connection type
   if (isExternal) {
-    // --- EXTERNAL URL LOGIC ---
-    const base = data.prefix.replace(/\/$/, '');
+    let base = data.prefix;
+    if (base.endsWith('/')) {
+      base = base.slice(0, -1);
+    }
+
     let apiPath = 'api/v1/query_range';
     if (data.subPath && data.subPath !== '') {
-      const sub = data.subPath.replace(/^\/|\/$/g, '');
-      apiPath = `${sub}/api/v1/query_range`;
+      if (data.subPath.startsWith('/')) {
+        data.subPath = data.subPath.slice(1);
+      }
+      if (data.subPath.endsWith('/')) {
+        data.subPath = data.subPath.slice(0, -1);
+      }
+      apiPath = `${data.subPath}/api/v1/query_range`;
     }
+
     url = `${base}/${apiPath}?${params.toString()}`;
   } else {
-    // --- KUBERNETES PROXY LOGIC (FIXED) ---
-    const sub = data.subPath ? data.subPath.replace(/^\/|\/$/g, '') : '';
-    const apiPath = sub ? `${sub}/api/v1/query_range` : 'api/v1/query_range';
-
-    // data.prefix is expected as "namespace/services/service-name:port"
-    url = `/api/v1/namespaces/${data.prefix}/proxy/${apiPath}?${params.toString()}`;
-  }
-
-  try {
-    if (isExternal) {
-      // Direct fetch for external/local URL
-      const response = await fetch(url, { method: 'GET' });
-
-      if (!response.ok) {
-        if (response.status === 404) {
-          throw new Error(`404 Not Found at: ${url}. Check your Endpoint and Subpath.`);
-        }
-        throw new Error(`Prometheus Error (${response.status}): ${response.statusText}`);
+    url = `/api/v1/namespaces/${data.prefix}/proxy/api/v1/query_range?${params.toString()}`;
+    if (data.subPath && data.subPath !== '') {
+      if (data.subPath.startsWith('/')) {
+        data.subPath = data.subPath.slice(1);
       }
-      return await response.json();
-    } else {
-      // Headlamp Proxy for K8s services
-      const response = await request(url, { method: 'GET', isJSON: false });
-
-      if (response.status !== 200) {
-        throw new Error(`K8s Proxy Error ${response.status}: Path was ${url}`);
+      if (data.subPath.endsWith('/')) {
+        data.subPath = data.subPath.slice(0, -1);
       }
-      return await response.json();
-    }
-  } catch (err: any) {
-    if (err.message.includes('Failed to fetch')) {
-      throw new Error(`Connection refused to ${url}. Did you enable --web.cors.origin=".*"?`);
+      url = `/api/v1/namespaces/${data.prefix}/proxy/${
+        data.subPath
+      }/api/v1/query_range?${params.toString()}`;
     }
-    throw err;
   }
-}
+
+  if (isExternal) {
+    const response = await fetch(url, { method: 'GET' });
+    return response.json();
+  }
+
+  const response = await request(url, {
+    method: 'GET',
+    isJSON: false,
+  });
+  if (response.status === 200) {
+    return response.json();
+  } else {
+    const error = new Error(response.statusText);
+    return Promise.reject(error);
+  }
+}

prometheus/src/util.ts

@@ -115,7 +115,9 @@ export function isMetricsEnabled(cluster: string): boolean {
 }
 
 /**
- * getPrometheusPrefix returns the prefix for the Prometheus metrics.
+ * Resolves the base address for accessing Prometheus for a cluster.
+ * Supports full HTTP/HTTPS URLs or `namespace/service` Kubernetes service proxy paths.
+ *
  * @param {string} cluster - The name of the cluster.
  * @returns {Promise<string | null>} The prefix for the Prometheus metrics, or null if not found.
  */