Error: Could not prefetch cinder_type provider 'openstack': Execution of '/usr/bin/openstack volume type list --quiet --format csv --long' returned 1: Could not determine a suitable URL for the plugin

[wuwei]

when use packstack and oepnstack-puppet install mitaka of openstack in centos7,install to cinder encountered the following error:
Error: Could not prefetch cinder_type provider 'openstack': Execution of '/usr/bin/openstack volume type list --quiet --format csv --long' returned 1: Could not determine a suitable URL for the plugin
Error: Execution of '/usr/bin/openstack volume type create --format shell --property volume_backend_name=lvm iscsi' returned 1: Could not determine a suitable URL for the plugin
Error: /Stage[main]/Main/Cinder::Type[iscsi]/Cinder_type[iscsi]/ensure: change from absent to present failed: Execution of '/usr/bin/openstack volume type create --format shell --property volume_backend_name=lvm iscsi' returned 1: Could not determine a suitable URL for the plugin

I found in ans.txt,the parameter CONFIG_CINDER_BACKEND default value is lvm.If the default value lvm is removed,installation will succeed.So I do not think generated configuration file needs to be given a default value for this item.I was using the following command to generate configuration file.
packstack --gen-answer-file=ans.txt