fix: resolve ssl certificate port issue

server/src/api/controllers/controllerUtils.ts

@@ -10,7 +10,10 @@ type WhoisModule = typeof whoiser;
 export const fetchMonitorCertificate = async (checker: SSLCheckerType, monitor: Monitor): Promise<SSLDetails> => {
 	const monitorUrl = new URL(monitor.url);
 	const hostname = monitorUrl.hostname;
-	const cert = await checker(hostname);
+	// An explicit port in the URL is the most visible to the user, so it takes precedence over monitor.port.
+	const urlPort = monitorUrl.port ? Number(monitorUrl.port) : undefined;
+	const port = urlPort ?? monitor.port;
+	const cert = await checker(hostname, port !== undefined ? { port } : undefined);
 	if (cert?.validTo === null || cert?.validTo === undefined) {
 		throw new Error("Certificate not found");
 	}

server/test/unit/utils/monitorCertificate.test.ts

@@ -0,0 +1,68 @@
+import { describe, expect, it } from "@jest/globals";
+import type { SSLDetails, SSLOptions } from "ssl-checker";
+import { fetchMonitorCertificate } from "../../../src/api/controllers/controllerUtils.ts";
+import type { Monitor } from "../../../src/domain/monitors/monitor.type.ts";
+
+const makeMonitor = (url: string, port?: number): Monitor =>
+	({
+		url,
+		port,
+		type: "http",
+	}) as unknown as Monitor;
+
+const cert: SSLDetails = {
+	daysRemaining: 30,
+	valid: true,
+	validFrom: "2026-01-01T00:00:00Z",
+	validTo: "2026-12-31T00:00:00Z",
+	validFor: ["example.com"],
+};
+
+const setup = () => {
+	const calls: { hostname: string; options?: SSLOptions }[] = [];
+	const checker = async (hostname: string, options?: SSLOptions) => {
+		calls.push({ hostname, options });
+		return cert;
+	};
+	return { calls, checker };
+};
+
+describe("fetchMonitorCertificate", () => {
+	it("uses the default port when none is specified", async () => {
+		const { calls, checker } = setup();
+
+		await fetchMonitorCertificate(checker, makeMonitor("https://example.com/health"));
+
+		expect(calls).toEqual([{ hostname: "example.com", options: undefined }]);
+	});
+
+	it("uses the port from the URL", async () => {
+		const { calls, checker } = setup();
+
+		await fetchMonitorCertificate(checker, makeMonitor("https://example.com:54321/health"));
+
+		expect(calls).toEqual([{ hostname: "example.com", options: { port: 54321 } }]);
+	});
+
+	it("falls back to monitor.port when the URL has no port", async () => {
+		const { calls, checker } = setup();
+
+		await fetchMonitorCertificate(checker, makeMonitor("https://example.com/health", 8443));
+
+		expect(calls).toEqual([{ hostname: "example.com", options: { port: 8443 } }]);
+	});
+
+	it("prefers the URL port over monitor.port", async () => {
+		const { calls, checker } = setup();
+
+		await fetchMonitorCertificate(checker, makeMonitor("https://www.myurl.com:52345/health", 443));
+
+		expect(calls).toEqual([{ hostname: "www.myurl.com", options: { port: 52345 } }]);
+	});
+
+	it("throws when the certificate has no expiry", async () => {
+		const checker = async () => ({ ...cert, validTo: undefined }) as unknown as SSLDetails;
+
+		await expect(fetchMonitorCertificate(checker, makeMonitor("https://example.com"))).rejects.toThrow("Certificate not found");
+	});
+});