'Executes cinder command for the given action.
:param action: the cli command to run using cinder
:type action: string
:param flags: any optional cli flags to use
:type flags: string
:param params: any optional positional args to use
:type params: string
:param fail_ok: if True an exception is not raised when the
cli return code is non-zero
:type fail_ok: boolean
:param endpoint_type: the type of endpoint for the service
:type endpoint_type: string
:param merge_stderr: if True the stderr buffer is merged into stdout
:type merge_stderr: boolean'

def cinder(self, action, flags='', params='', fail_ok=False, endpoint_type='publicURL', merge_stderr=False):

    flags += ('    --endpoint-type    %s' % endpoint_type)
    return self.cmd_with_auth('cinder', action, flags, params, fail_ok, merge_stderr)
