The following endpoint returns the disk space of the CA Gateway server for a group.  

https://<HOST>:<MONITOR_HOST_PORT>/<management.endpoints.web.base-path>/health/{group}/diskSpace

Where group is one of the groups listed by the health endpoint. For example, to check the disk space for the custom group.

https://localhost:9444/cagw/management/actuator/health/custom/diskSpace

If the server is up, this endpoint will return a response like the following.

{"status":"UP","details":{"total":1013309239296,"free":765931622400,"threshold":10485760,"exists":true}}