Docker RUN fails with "returned a non-zero code: 6"

Question

I have the following in my docker file:

RUN sudo apt-get install sshpass -y
RUN sshpass -p userPassword scp -r user@server:~/data/* ./

But when I try and build my image it fails with:

Exception caught: The command '/bin/sh -c sshpass -p userPassword scp -r user@server:~/data/* ./' returned a non-zero code: 6 -> [Help 1]

However, if I remove these lines, build the image, ssh onto the container and manually run the command from bash it works perfectly.

Can anyone tell me how to get around this?

Answer 1

The exit code 6 means that "Host public key is unknown. sshpass exits without confirming the new key."

So either you populate before that the ~/.ssh/known_hostswith the fingerprint of the host, or just ignore the check of the host public key by adding the StrictHostKeyChecking=no option to the scp.

The updated line would look like that:

RUN sshpass -p userPassword scp -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -r user@server:~/data/* ./