Health check

A simple health check is mapped to /v1/_health which returns 200 OK if the server is “healthy”, and 500 if it’s “unhealthy”. The health check is configured to simply read the root app object from the DAO, Search and Cache to ensure there are active connections with each resource. The implementation is done in a class called HealthUtils in the “utils” package of para-server.

The health check endpoint is publicly accessible so it can be easily called by any application or a load balancer. To prevent excessive calls to the health check end point, the health check method is only allowed to run at a fixed interval (defaults to once per minute, but can be configured using para.health.check_interval).

An initial health check is done on startup and a warning is printed if Para is not initialized, which is actually just an assumption at this point. The only way to distinguish between “not initialized” and “unhealthy” is to check for connection errors in the logs. Para starts as unhealthy, but once the root app is created, i.e. /v1/_setup is called, the status is updated to “healthy”.

Here’s how to programmatically check the health of the system:

HealthUtils.getInstance().performHealthCheck();
boolean isHealthy = HealthUtils.getInstance().isHealty();

To disable health checking, set para.health_check_enabled = false.