feat(frontend): basic health check

Author: gregory-j-baker

frontend/app/.server/express/handlers.ts

@@ -46,7 +46,6 @@ export function rrRequestHandler(viteDevServer?: ViteDevServer) {
   return createRequestHandler({
     mode: serverEnvironment.NODE_ENV,
     getLoadContext: (request, response) => ({
-      LogFactory: LogFactory,
       nonce: response.locals.nonce,
       session: request.session,
     }),

frontend/app/entry.server.tsx

@@ -17,15 +17,15 @@ import { getLanguage } from '~/utils/i18n-utils';
 
 /* eslint-disable no-param-reassign */
 
+const log = LogFactory.getLogger(import.meta.url);
+
 export default async function handleRequest(
   request: Request,
   responseStatusCode: number,
   responseHeaders: Headers,
   routerContext: EntryContext,
   loadContext: AppLoadContext,
 ) {
-  const log = LogFactory.getLogger(import.meta.url);
-
   const language = getLanguage(request);
   const i18n = await initI18next(language);
 
@@ -86,7 +86,7 @@ export default async function handleRequest(
 }
 
 // https://reactrouter.com/explanation/special-files#handleerror
-export function handleError(error: unknown, { context, request }: LoaderFunctionArgs | ActionFunctionArgs) {
+export function handleError(error: unknown, { context, params, request }: LoaderFunctionArgs | ActionFunctionArgs) {
   if (!request.signal.aborted) {
     const log = context.LogFactory.getLogger(import.meta.url);
     log.error('Uncaught error while handling request:', error);

frontend/app/routes.ts

@@ -42,6 +42,7 @@ export default [
   route('/api/readyz', 'routes/api/readyz.ts'),
   route('/api/buildinfo', 'routes/api/buildinfo.ts'),
   route('/api/client-env', 'routes/api/client-env.ts'),
+  route('/api/health', 'routes/api/health.ts'),
   route('/api/translations', 'routes/api/translations.ts'),
 
   // auth routes

frontend/app/routes/api/health.ts

@@ -0,0 +1,49 @@
+import type { HealthCheckOptions } from '@dts-stn/health-checks';
+import { execute } from '@dts-stn/health-checks';
+
+import type { Route } from './+types/health';
+
+import { serverEnvironment } from '~/.server/environment';
+import { getRedisClient } from '~/.server/redis';
+
+export async function loader({ context, params, request }: Route.LoaderArgs) {
+  const { include, exclude, timeout } = Object.fromEntries(new URL(request.url).searchParams);
+
+  const redisHealthCheck = { name: 'redis', check: () => void getRedisClient().ping() };
+
+  const healthCheckOptions: HealthCheckOptions = {
+    excludeComponents: toArray(exclude),
+    includeComponents: toArray(include),
+    includeDetails: isAuthorized(request),
+    metadata: {
+      buildId: serverEnvironment.BUILD_ID,
+      version: serverEnvironment.BUILD_VERSION,
+    },
+    timeoutMs: toNumber(timeout),
+  };
+
+  const useRedis = serverEnvironment.SESSION_TYPE === 'redis';
+
+  if (!useRedis) {
+    healthCheckOptions.excludeComponents ??= [];
+    healthCheckOptions.excludeComponents.push(redisHealthCheck.name);
+  }
+
+  const summary = await execute([redisHealthCheck], healthCheckOptions);
+
+  return Response.json({ summary });
+}
+
+function isAuthorized(request: Request): boolean {
+  return false; // TODO
+}
+
+function toArray(str?: string): string[] | undefined {
+  const result = str?.split(',').filter(Boolean);
+  return result && result.length > 0 ? result : undefined;
+}
+
+function toNumber(str?: string): number | undefined {
+  const num = parseInt(str ?? '');
+  return isNaN(num) ? undefined : num;
+}

frontend/package-lock.json

@@ -18,6 +18,7 @@
     "typecheck": "react-router typegen && tsc"
   },
   "dependencies": {
+    "@dts-stn/health-checks": "^2.0.0",
     "@opentelemetry/api": "^1.9.0",
     "@opentelemetry/auto-instrumentations-node": "^0.55.0",
     "@opentelemetry/exporter-metrics-otlp-proto": "^0.57.0",