ssh fails to guest in tempest run, "Starting dropbear sshd: WARN: generating key of type ecdsa failed!" in guest console log

[Matt Riedemann]

I've started noticing these:

http://logstash.openstack.org/#dashboard/file/logstash.json?query=message%3A%5C%22WARN%3A%20generating%20key%20of%20type%5C%22%20AND%20message%3A%5C%22failed!%5C%22%20AND%20tags%3A%5C%22console%5C%22%20AND%20voting%3A1&from=7d

20 hits in voting jobs since Oct 21, check and gate, all failures.

[Matt Riedemann (mriedem)]

Also, multiple branches but looks like it's mostly OVH node providers for some reason.

[melanie witt (melwitt)]

FWIW I doubt this is a bug, this message is seen on any ssh failure (because the guest console is only logged to the job-output.txt when ssh fails).

(later) I think I can confirm that this message does not guarantee an ssh failure as it appears even on successful ssh connections. I have found that the guest console is logged on successful ssh connections in the tempest_log.txt file in jobs. This filename however is not indexed by our logstash, so I can't post a query here to show it. Here's an excerpt of a recent run [1]:

WARN: failed: route add -net "0.0.0.0/0" gw "10.1.0.1"
cirros-ds 'net' up at 8.93
checking http://169.254.169.254/2009-04-04/instance-id
successful after 1/20 tries: up 9.54. iid=i-0000000c
failed to get http://169.254.169.254/2009-04-04/user-data
warning: no ec2 metadata for user-data
found datasource (ec2, net)
Top of dropbear init script
Starting dropbear sshd: WARN: generating key of type ecdsa failed!
OK
[...]
login as 'cirros' user. default password: 'cubswin:)'. use 'sudo' for root.
tempest-testnetworkadvancedserverops-server-1460677064 login: _log_console_output tempest/scenario/manager.py:578
2021-01-13 04:36:06.386 8834 INFO tempest.lib.common.ssh [-] Creating ssh connection to '172.24.5.174:22' as 'cirros' with public key authentication
2021-01-13 04:36:06.404 8834 INFO paramiko.transport [-] Connected (version 2.0, client dropbear_2012.55)
2021-01-13 04:36:06.789 8834 INFO paramiko.transport [-] Authentication (publickey) successful!
2021-01-13 04:36:06.804 8834 INFO tempest.lib.common.ssh [-] ssh connection to cirros@172.24.5.174 successfully created

Based on this, I'm going to close this bug as Invalid.

[1] https://zuul.opendev.org/t/openstack/build/9c4c5ca5e99a4becb2f24762972bc8a0/log/controller/logs/tempest_log.txt#9504-9549