ssh-keyscan 抛出写入：操作超时

Question

I have gitlab runner installed on kube.netes . I am trying to build docker image from a Dockerfile which needs to clone private repositories over ssh. I have added ssh-keyscan to get public key of the repo URL.
It throws following error most of the times:

write (git..com): Operation timed out

I have tried increasing timeout but the behaviour is still the same.

This is the command I am running from Dockerfile

RUN mkdir -p -m 0600 /root/.ssh && ssh-keyscan  -vvv -T 300 -p  <port> git.<kygitlab>.com >> /root/.ssh/known_hosts

The public key should be stored into know_hosts file without any error. This works fine in my local system but throws an error when executed with gitlab CI on kube.netes.

Answer 1

The problem is:

• you don't need to update only the known_hosts,
• you also need a private/public key pair (in the ~/.ssh Docker image folder), with the public key registered on the remote private repo hosting service side.

Only that would allow you to access and clone a private remote repo.

Answer 2

Short Explanation: Check if SSH traffic is enabled, if not allow SSH traffic. You can run the following command to know if it is enabled. You can replace github.com with your git host instance.

ssh -T git@github.com

More Details: I faced a similar issue, but the platform I am working on is different. We are building a docker image on docker executor in GitLab runner . So, here, the image is getting built inside another docker container. The concept is called Docker-in-Docker which is explained here .

After spending time, we got to know that SSH (port:22) traffic is blocked on the host machine which cascades to all the guests (docker containers) on it. Once, we enabled the SSH traffic, it worked like a charm.