I am trying Disk Image Builder and followed initial instructions given in DIB documentation. I tried creating basic ubuntu image with 'disk-image-create ubuntu vm" command. I am executing this on CentOS7 server installation on virtual box machine on my laptop. I am getting following error -

2020-07-22 14:38:38.181 | INFO diskimage_builder.block_device.utils [-] Calling [sudo sync]
2020-07-22 14:38:38.480 | INFO diskimage_builder.block_device.utils [-] Calling [sudo fstrim --verbose /tmp/dib_build.kjzn9JEP/mnt/]
2020-07-22 14:38:38.692 | INFO diskimage_builder.block_device.utils [-] Calling [sudo umount /tmp/dib_build.kjzn9JEP/mnt/]
2020-07-22 14:38:38.969 | INFO diskimage_builder.block_device.utils [-] Calling [sudo kpartx -d /dev/loop0]
2020-07-22 14:38:38.986 | Traceback (most recent call last):
2020-07-22 14:38:38.986 |   File "/root/dib-virtualenv/bin/dib-block-device", line 8, in <module>
2020-07-22 14:38:38.986 |     sys.exit(main())
2020-07-22 14:38:38.986 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/cmd.py", line 120, in main
2020-07-22 14:38:38.986 |     return bdc.main()
2020-07-22 14:38:38.986 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/cmd.py", line 115, in main
2020-07-22 14:38:38.986 |     self.args.func()
2020-07-22 14:38:38.986 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/cmd.py", line 39, in cmd_umount
2020-07-22 14:38:38.986 |     self.bd.cmd_umount()
2020-07-22 14:38:38.986 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/blockdevice.py", line 442, in cmd_umount
2020-07-22 14:38:38.986 |     node.umount()
2020-07-22 14:38:38.986 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/level1/partition.py", line 88, in umount
2020-07-22 14:38:38.986 |     self.partitioning.umount()
2020-07-22 14:38:38.986 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/level1/partitioning.py", line 228, in umount
2020-07-22 14:38:38.986 |     self.state['blockdev'][self.base]['device']])
2020-07-22 14:38:38.986 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/utils.py", line 143, in exec_sudo
2020-07-22 14:38:38.986 |     raise e
2020-07-22 14:38:38.987 | diskimage_builder.block_device.exception.BlockDeviceSetupException: exec_sudo failed
2020-07-22 14:38:39.974 | INFO diskimage_builder.block_device.level3.mount [-] Called for [mount_mkfs_root]
2020-07-22 14:38:39.974 | INFO diskimage_builder.block_device.utils [-] Calling [sudo sync]
2020-07-22 14:38:40.086 | INFO diskimage_builder.block_device.utils [-] Calling [sudo fstrim --verbose /tmp/dib_build.kjzn9JEP/mnt/]
2020-07-22 14:38:40.101 | Traceback (most recent call last):
2020-07-22 14:38:40.101 |   File "/root/dib-virtualenv/bin/dib-block-device", line 8, in <module>
2020-07-22 14:38:40.101 |     sys.exit(main())
2020-07-22 14:38:40.101 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/cmd.py", line 120, in main
2020-07-22 14:38:40.101 |     return bdc.main()
2020-07-22 14:38:40.101 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/cmd.py", line 115, in main
2020-07-22 14:38:40.101 |     self.args.func()
2020-07-22 14:38:40.101 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/cmd.py", line 39, in cmd_umount
2020-07-22 14:38:40.102 |     self.bd.cmd_umount()
2020-07-22 14:38:40.102 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/blockdevice.py", line 442, in cmd_umount
2020-07-22 14:38:40.102 |     node.umount()
2020-07-22 14:38:40.102 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/level3/mount.py", line 111, in umount
2020-07-22 14:38:40.102 |     self.state['mount'][self.mount_point]['path']])
2020-07-22 14:38:40.102 |   File "/root/dib-virtualenv/lib/python2.7/site-packages/diskimage_builder/block_device/utils.py", line 143, in exec_sudo

2020-07-22 14:38:40.102 |     raise e
2020-07-22 14:38:40.102 | diskimage_builder.block_device.exception.BlockDeviceSetupException: exec_sudo failed

Can you please help me understand issue here? 

Thanks,

Prakash