A storage system failure detection and failover application includes a command execution engine that loads and interprets both user-defined storage system management functions, and vendor-defined storage system management functions. The user-defined storage system management functions allow the system to detect and handle failure conditions indicating both the current state of an active storage system, and the current state of one or more applications that consume a storage service or services provided by the active storage system. The user-defined storage management functions also allow the system to perform failover processing in a way that allows applications to perform application-specific processing during storage system failover.