Problem configuring Gitlab CI -> ssh: handshake failed

GitLab CI/CD
3

See Preparation failed: ssh: handshake failed: ssh: unable to authenticate, attempted methods [none publickey], no supported methods remain

Here is debug process for this situation.

Verify you can logging to remote ssh server manually using same local user and same key file than gitlab-runner

sudo su - USER

eval `ssh-agent -s`
ssh-add YOUR_SSH_KEY_FILE
ssh REMOTEU_SER@REMOTE_SERVER

You should solve any issue here before continue.

Run gitlab-runner with log in debug mode

sudo vi /etc/gitlab-runner/config.toml

Add log_level = "debug"

# Sample
concurrent = 1
check_interval = 0
log_level = "debug"
...

Then restart gitlab-runner

sudo gitlab-runner restart

Retry to run buggy job.

If it does not help go to next step.

Launch remote sshd in debug mode

Run SSH daemon on another port as a part of the command (then you don’t need to lost your existing session, if already connect thought ssh)

sudo /usr/sbin/sshd -d -p 2200
# sudo /usr/sbin/sshd -dd -p 2200 - if you need more logs
# sudo /usr/sbin/sshd -ddd -p 2200 - if you need all logs

Warn: You should run this for each ssh connection.

Then modify gitlab-runner configuration (on gitlab runner host)

sudo vi /etc/gitlab-runner/config.toml

Add port = "2200"

...
[[runners]]
  name = "XXXXX"
  url = "https://XXXXX/"
  token = "XXXXX"
  executor = "ssh"
  [runners.ssh]
    user = "XXXXX"
    host = "XXXXX"
    port = "2200"
    identity_file = "XXXXX"
...

Retry to run buggy job.

On console sshd console you are able to see all gitlab-runner actions and you should be able to understand what is the issue.

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