feat: add healthchecks (#1187)

apps/nextjs/src/app/api/health/live/route.ts

@@ -0,0 +1,91 @@
+import { performance } from "perf_hooks";
+
+import { db } from "@homarr/db";
+import { logger } from "@homarr/log";
+import { handshakeAsync } from "@homarr/redis";
+
+export async function GET() {
+  const timeBeforeHealthCheck = performance.now();
+  const response = await executeAndAggregateAllHealthChecksAsync();
+  logger.info(`Completed healthcheck after ${performance.now() - timeBeforeHealthCheck}ms`);
+
+  if (response.status === "healthy") {
+    return new Response(JSON.stringify(response), {
+      status: 200,
+    });
+  }
+
+  return new Response(JSON.stringify(response), {
+    status: 500,
+  });
+}
+
+const executeAndAggregateAllHealthChecksAsync = async (): Promise<{
+  healthChecks: Record<string, object>;
+  status: "healthy" | "unhealthy";
+}> => {
+  const healthChecks = [
+    executeHealthCheckSafelyAsync("database", async () => {
+      // sqlite driver does not support raw query execution. this is for a heartbeat check only - it doesn't matter if data is returned or not
+      await db.query.serverSettings.findFirst();
+      return {};
+    }),
+    executeHealthCheckSafelyAsync("redis", async () => {
+      await handshakeAsync();
+      return {};
+    }),
+  ];
+
+  const healthCheckResults = await Promise.all(healthChecks);
+  const anyUnhealthy = healthCheckResults.some((healthCheck) => healthCheck.status === "unhealthy");
+
+  const healthCheckValues = healthCheckResults.reduce(
+    (acc, healthCheck) => {
+      acc[healthCheck.name] = {
+        status: healthCheck.status,
+        ...healthCheck.values,
+      };
+      return acc;
+    },
+    {} as Record<string, object>,
+  );
+
+  return {
+    status: anyUnhealthy ? "unhealthy" : "healthy",
+    healthChecks: healthCheckValues,
+  };
+};
+
+const executeHealthCheckSafelyAsync = async (
+  name: string,
+  callback: () => Promise<object>,
+): Promise<HealthCheckResult> => {
+  try {
+    const currentTimeBeforeCallback = performance.now();
+    const values = await callback();
+    return {
+      name,
+      status: "healthy",
+      values: {
+        ...values,
+        latency: performance.now() - currentTimeBeforeCallback,
+      },
+    };
+  } catch (error) {
+    // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
+    logger.error(`Healthcheck '${name}' has failed: ${error}`);
+    return {
+      status: "unhealthy",
+      values: {
+        error,
+      },
+      name,
+    };
+  }
+};
+
+interface HealthCheckResult {
+  status: "healthy" | "unhealthy";
+  name: string;
+  values: object;
+}

apps/nextjs/src/app/api/health/ready/route.ts

@@ -0,0 +1,5 @@
+export function GET() {
+  return new Response(undefined, {
+    status: 200,
+  });
+}