Simple UP/DOWN Health Check Response

Simple Health Check Response

The simplest health check response returns only a status field indicating whether the service is running.

Response Format

{
  "status": "UP"
}

Or when the service is unhealthy:

{
  "status": "DOWN"
}

HTTP Status Codes

The HTTP status code carries the primary health signal:

Status	HTTP Code	Meaning
UP	200 OK	Service is healthy
DOWN	503 Service Unavailable	Service is unhealthy

When to Use Simple Format

Simple responses are ideal when:

• Your load balancer only checks HTTP status codes (e.g., AWS ALB, Nginx upstream)
• You need a lightweight endpoint with minimal processing overhead
• The health check runs at high frequency (every 1-5 seconds)
• You don't need to expose internal component details externally

Implementation Example

app.get('/health', (req, res) => {
  const isHealthy = checkBasicHealth();
  res.status(isHealthy ? 200 : 503).json({
    status: isHealthy ? 'UP' : 'DOWN'
  });
});

Most cloud load balancers and reverse proxies only need the HTTP status code, making this the most efficient option for external health checks.