Health checks

Health checks are a way to ensure that your applications and services are running correctly. They allow Coolify to monitor the health of your resources and ensure that traffic is only routed to healthy instances. This for example important for Rolling Updates to work correctly.

Traefik

When using Traefik as the reverse proxy, health checks are an integral part of how it routes traffic to your resources.

Enabled

If your resource has health checks enabled, Traefik will only route traffic to it if the health check passes. If the health check fails, Traefik will not route traffic to the resource.

It will cause the resource to return a 404 Not Found or No available server error.

Disabled

If your resource has health checks disabled, Traefik will route traffic to it regardless of the health check status.

Configure Health checks

Applications

There are two ways to configure health checks for your applications:

1. Using the UI: You can set up health checks directly in the Coolify UI when creating or editing an application. You can specify the path to check, the expected response code, and the interval for checking. It will be required that the container has either curl or wget installed to perform the health checks.

2. Using the Dockerfile: You can also define health checks in your Dockerfile using the HEALTHCHECK instruction. This allows you to specify how the health check should be performed, including the command to run and the expected response.

If there are healthchecks both in the UI and in the Dockerfile defined and enabled, the Dockerfile will take precedence.

Service Stacks

Services or Applications that use the Docker Compose Build Pack require their health checks to be defined in the Dockerfile of each service, or in their docker-compose.y[a]ml file using the healthcheck attribute.

When to use health checks?

It is recommended to enable health checks for all your resources. This way, you can ensure that only healthy resources are receiving traffic.

But if you cannot set up health checks for some reason, you can disable them.

Just be aware that if the resource is unhealthy, it will still receive traffic.