Tuesday, August 26, 2014

"Host key verification failed" error while resizing instance Openstack

Setting allow_resize_to_same_host=true will enable the resizing in All in one model of installation . but if we have mutiple controller and compute node's we will be getting an authentication error as following

"/usr/lib/python2.6/site-packages/nova/virt/libvirt/", line 4907,
in migrate_disk_and_power_off\n utils.execute(\'ssh\', dest, \'mkdir\', \'-p\', inst_base)\n', '
File "/usr/lib/python2.6/site-packages/nova/", line 165, in execute\n return processutils.execute(*cmd, **kwargs)\n', '
File "/usr/lib/python2.6/site-packages/nova/openstack/common/", line 193, in execute\n cmd=\' \'.join(cmd))\n',
"ProcessExecutionError: Unexpected error while running command.\nCommand: ssh
mkdir -p /var/lib/nova/instances/5d5ced81-6fb1-4028-97cd-686e450d1bab\nExit code: 255\nStdout: ''\nStderr:
'Host key verification failed.\\r\\n'\n"]

This is due to a bug in nova as told in below bug report which can be solved by enabling password less authentication between the compute and controller node's nova user .

By default the nova user does not have a shell so we need to enable the shell and do steps to enable password less authentication between all the server .

Enable shell for nova user

In all the controller and compute server’s enable nova user.

sed -i "s/\/var\/lib\/nova:\/sbin\/nologin/\/var\/lib\/nova:\/bin\/bash/g" /etc/passwd

cat /etc/passwd |grep nova

nova:x:162:162:OpenStack Nova Daemons:/var/lib/nova:/bin/bash

Enable password less authentication

Between all the compute and controller nodes create password less authenticatioin for user nova.


su - nova



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