Readiness and liveness

When http_status_port is set in the configuration file or the environment variable THINGSDB_HTTP_STATUS_PORT then /status, /ready and /healthy are available. These can be used for readiness and liveness requests.

Liveness

The ThingsDB /healthy check will respond with a 200 OK whenever possible and will never respond with an error. So only if no response is received in some reasonable amount of time, the node should be considered as unhealthy. It is common to use the /healthy check as liveness probe in environments like Kubernetes.

Readiness

Besides the /healthy check there is also a /ready check. This check responds with 200 OK if the node has one of the following status: READY, AWAY, or AWAY_SOON. With any other status, for example, SYNCHRONIZING, the /ready check will respond with 503 Service Unavailable (NOK).

Since v0.9.20 ThingsDB will also respond with 200 OK to a /ready request when all of the following conditions are met:

• ThingsDB must be started with the --deploy argument.
• The ThingsDB node status is SYNCHRONIZING.
• At least one ThingsDB node is unavailable (checked using at least 3 attempts).