The RMR runtime package includes a health check binary which provides a simple mechanism to check the state of an xAPP which is based on RMR. The binary will send a healt check message to the application and wait for a response. If no response is received, or an error response is received, the binary exits with a "bad" (1) return code. If an OK response is received then the exit code is "good" (0).
By default the health check binary is installed as /usr/local/bin/health_ck. When invoked with no command line parameters it will attempt to contact the xAPP running at localhost:4560 by sending an RMR health check message. The timeout period for a response is 3 seconds. The binary supports two, optional, parameters allowing it to connect to a different xAPP, and/or to allow for a longer timeout period. The usage string for the binary is:
rmr_probe [-h host:port] [-t timeout-seconds]
The rmr_probe application sends a message with the type RIC_HEALTH_CHECK_REQ and expects a response with the RIC_HEALTH_CHECK_RESP message type. The payload of the message is expected to be UTF-8 (ASCII) where the first token is either "OK" or "ERR". Any subsequent tokens are optional and serve as an extended "reason". The state and reason are written to standard error.
If a response with ERR is received, or no response within the timeout period is received, the exit code is 1 (bad), otherwise the exit code is 0 (good).