Probe Command

The probe command checks the health of the given application. It should be a UNIX command complete with its arguments that is acceptable by hatimerun. The exit status of the probe command is used to determine the severity of the failure of the application. This exit status, called probe status, must be an integer between 0 (for success) and 100 (for complete failure). The probe status is used with in the GDS probing algorithm to take the decision of restarting the application locally, versus failing it over to another node.

If the probe command is omitted and the application uses network, GDS provides its own simple probe. This alternative probe simply connects to the application on the given hostname and port number. If the connect succeeds, it disconnects immediately. If both connect and disconnect succeed, the application is deemed to be running healthily.

The probe provided with GDS is only intended to be a simple substitute for the fully functioning application specific probe.