fix(probe): use protocol-aware default port for endpoint probing

src/probe.ts

@@ -7,16 +7,22 @@ export type ProbeResult = { ok: boolean; ms: number; error?: string }
  * Opens a TCP connection to the host and port parsed from `endpoint` to verify
  * reachability before the OTel SDK initialises. Resolves within 5 seconds.
  */
-export function probeEndpoint(endpoint: string): Promise<ProbeResult> {
-  let host: string
-  let port: number
+export function parseEndpoint(endpoint: string): { host: string; port: number } | null {
   try {
     const url = new URL(endpoint)
-    host = url.hostname
-    port = parseInt(url.port || "4317", 10)
+    const defaultPort = url.protocol === "http:" ? 80 : url.protocol === "https:" ? 443 : 4317
+    return { host: url.hostname, port: url.port ? parseInt(url.port, 10) : defaultPort }
   } catch {
+    return null
+  }
+}
+
+export function probeEndpoint(endpoint: string): Promise<ProbeResult> {
+  const parsed = parseEndpoint(endpoint)
+  if (!parsed) {
     return Promise.resolve({ ok: false, ms: 0, error: `invalid endpoint URL: ${endpoint}` })
   }
+  const { host, port } = parsed
   return new Promise((resolve) => {
     const start = Date.now()
     const socket = net.createConnection({ host, port }, () => {

tests/probe.test.ts

@@ -1,5 +1,27 @@
 import { describe, test, expect } from "bun:test"
-import { probeEndpoint } from "../src/probe.ts"
+import { probeEndpoint, parseEndpoint } from "../src/probe.ts"
+
+describe("parseEndpoint", () => {
+  test("uses port 80 for http:// URLs without explicit port", () => {
+    expect(parseEndpoint("http://api.honeycomb.io")).toEqual({ host: "api.honeycomb.io", port: 80 })
+  })
+
+  test("uses port 443 for https:// URLs without explicit port", () => {
+    expect(parseEndpoint("https://api.honeycomb.io")).toEqual({ host: "api.honeycomb.io", port: 443 })
+  })
+
+  test("uses explicit port when provided", () => {
+    expect(parseEndpoint("http://localhost:4317")).toEqual({ host: "localhost", port: 4317 })
+  })
+
+  test("defaults to 4317 for unknown protocols without explicit port", () => {
+    expect(parseEndpoint("grpc://api.honeycomb.io")).toEqual({ host: "api.honeycomb.io", port: 4317 })
+  })
+
+  test("returns null for invalid URLs", () => {
+    expect(parseEndpoint("not a url")).toBeNull()
+  })
+})
 
 describe("probeEndpoint", () => {
   test("returns error for malformed URL (no scheme)", async () => {