Health endpoints

Health endpoints#

A load balancer, an orchestrator or a monitoring system asks each Querona node two questions: is it alive, and does it accept clients. Querona answers both over HTTP without a login, and gives administrators the state of the node in more detail.

Endpoint

Access

Answer

GET /health/live

Anonymous

200 with {"status":"Live"} whenever the web server of the node answers.

GET /health/ready

Anonymous

200 with {"status":"Ready"} while the node accepts client connections, and 503 with {"status":"NotReady"} while it is starting or its TDS listener is stopped.

GET /api/1.0/health

A login that holds VIEW SERVER STATE

The health details of the node, described below.

The endpoints are served on the port of the Administrative Portal.

Load balancers#

Point the health probe of a load balancer at /health/ready on the port of the Administrative Portal, and treat 200 as healthy. A node that is starting answers 503, and a node that is stopping refuses the connection, so the load balancer stops sending it new connections in both cases. The answer carries no role and no version.

Liveness probes#

/health/live checks nothing beyond the web server itself. A problem outside the process, such as an unreachable metabase, therefore never makes an orchestrator restart Querona.

Health details#

A login that holds the VIEW SERVER STATE permission reads the details of the node with GET /api/1.0/health:

  • the readiness status, as /health/ready reports it;

  • the id and name of the instance;

  • the TDS port and whether the TDS listener accepts connections;

  • the web port and whether it serves HTTPS;

  • whether the metabase answered a test query within five seconds, how long it took and, when it did not answer, why;

  • when the Querona process started, in UTC;

  • the build version.

A login without the permission gets the answer VIEW SERVER STATE permission was denied on object ‘server’, database ‘master’.

For example, in PowerShell:

Invoke-WebRequest -Uri https://querona.example.com/health/ready -UseBasicParsing |
    Select-Object StatusCode, Content

See also#