Unable to connect to instance via temporary key (generated by API)

The problem was not caused by time drift.
Problem was related to SSH keys. I did not realize that I need to use cert key also. So, thank you for that URL to SSH docs, based on this I was able to solve problem.

To anyone who have problem with temporary key from API ( https://docs.aws.amazon.com/cli/latest/reference/lightsail/get-instance-access-details.html )

1. Save certKey in temp_id_rsa.pub
2. Save privateKey in temp_id_rsa
3. Connect to instance with SSH: ssh ubuntu@XXX.XXX.XXX.XXX -i temp_id_rsa

There's a popular root cause for this: perhaps your instance system clock drifted too much.

SSH user certificates are time sensitive, in Lightsail they last few minutes only. If the clock on instance is wrong, they will never be usable.

Does Lightsail browser-based SSH work for you, @mariuszm?

To check, replace placeholders with the values that apply for you and visit the resulting URL:

https://lightsail.aws.amazon.com/ls/remote/YOUR_REGION/instances/YOUR_INSTANCE_NAME/terminal?protocol=ssh

See also:

• Learn more about SSH user certificates: http://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/usr.bin/ssh/PROTOCOL.certkeys?content-type=text/plain