func FileChecker(f string) health.Checker
FileChecker checks the existence of a file and returns an error if the file exists.
func HTTPChecker(r string, statusCode int, timeout time.Duration, headers http.Header) health.Checker
HTTPChecker does a HEAD request and verifies that the HTTP status code returned matches statusCode.
func TCPChecker(addr string, timeout time.Duration) health.Checker
TCPChecker attempts to open a TCP connection.