Health Check

A health check is a scheduled HTTP or TCP request that you can configure to run on a repeating basis to ensure that a service is healthy.

For example, you can configure an HTTP health check to ping the root URL of your site and ensure that the response is HTTP 200 (OK). In the cloud control panel, you can only define the HTTP path that you would like to have checked.

App Platform

Health checks ensure that your app is communicating with “healthy” containers in App Platform. The load balancer for App Platform only direct traffic to containers that passed the health checks. If the container fails the health checks, App Platform’s load balancer will remove the container from rotation until the container passes the health checks.

If you want to learn more about the error codes associated with health checks, see App Platform Error Code Reference.

Load Balancers

DigitalOcean Load Balancers only use Droplets that pass health checks. The load balancer automatically removes Droplets that fail health checks from rotation and adds them back when their health checks pass.

You are able to configure how the load balancer interacts with health checks, such as its check interval, response timeout, and unhealthy threshold. For example, you can specify how many seconds the load balancer will wait between health checks.

To configure the load balancer to balance TCP, you need to add a TCP-forwarding rule and a TCP health check. The success criteria for HTTP and HTTPS health checks is a status code response in the range of 200 to 399. The success criteria for TCP health checks is completing a TCP handshake to connect.

HTTP health checks use HTTP/1.1. If your web server uses a version other than HTTP/1.1, the headers in the health check may not be compatible and you’ll need to use a TCP check instead.

Note
HTTP and HTTPS health checks may fail with Droplets running Apache on Rocky Linux because the default Apache page returns a 403 Forbidden HTTP response code. To fix this, either change the health check from HTTP/HTTPS to TCP or configure Apache to return a 200 OK response code by creating an HTML page in Apache’s root directory.

Health Check Articles

Configure health checks that monitor the health and readiness of Gradient Deployments.
Use TCP load balancing for applications that don’t speak HTTP.
View and modify a load balancer’s backend Droplet pool, view graphs of traffic patterns and infrastructure health, and customize the load balancer’s forwarding rules, sticky sessions, health checks, SSL forwarding, and PROXY protocol.