feat(site): add healthz page (#458)

Summary:

This is a port of v1 healthz page to v2

Impact:

A simple way to check site health (requires no auth). Good smoke test
for e2e.

site/e2e/pom/HealthzPage.ts

@@ -0,0 +1,13 @@
+import { Locator, Page } from "@playwright/test"
+import { BasePom } from "./BasePom"
+
+export class HealthzPage extends BasePom {
+  constructor(baseURL: string | undefined, page: Page) {
+    super(baseURL, "/healthz", page)
+  }
+
+  getOk(): Locator {
+    const locator = this.page.locator("text=ok")
+    return locator
+  }
+}

site/e2e/tests/healthz.spec.ts

@@ -0,0 +1,8 @@
+import { test } from "@playwright/test"
+import { HealthzPage } from "../pom/HealthzPage"
+
+test("Healthz is available without authentication", async ({ baseURL, page }) => {
+  const healthzPage = new HealthzPage(baseURL, page)
+  await page.goto(healthzPage.url, { waitUntil: "networkidle" })
+  await healthzPage.getOk().waitFor({ state: "visible" })
+})

site/src/app.tsx

@@ -14,6 +14,7 @@ import { ProjectsPage } from "./pages/projects"
 import { ProjectPage } from "./pages/projects/[organization]/[project]"
 import { CreateWorkspacePage } from "./pages/projects/[organization]/[project]/create"
 import { WorkspacePage } from "./pages/workspaces/[workspace]"
+import { HealthzPage } from "./pages/healthz"
 
 export const App: React.FC = () => {
   return (
@@ -45,6 +46,7 @@ export const App: React.FC = () => {
                 <Route index element={<IndexPage />} />
 
                 <Route path="login" element={<SignInPage />} />
+                <Route path="healthz" element={<HealthzPage />} />
                 <Route path="cli-auth" element={<CliAuthenticationPage />} />
 
                 <Route path="projects">

site/src/pages/healthz.tsx

@@ -0,0 +1,8 @@
+import React from "react"
+
+/**
+ * HealthzPage is a page that is available without authentication that is used
+ * for reporting whether or not the Dashboard is online. It should be
+ * accessible by humans and services.
+ */
+export const HealthzPage: React.FC = () => <div>ok</div>