When I pulled the centos image, I found the version of my own ubuntu that was displayed when viewing the system version in this image.
A Docker container ist not a vm. Containers share the hosts kernel, which makes it no surprise that the hosts version is returned.
May I suggest to read docker-overview?
Thank you for your reply. This is my first time using docker, I have encountered a problem, I thought this might be the cause of the error. Now it seems that I need to think about other reasons. I will take a close look this document, thank you.
If you describe your problem (idealy including error messages) and the exact commands you used to get there, I am sure someone will figure out what needs to be done. If Dockerfiles and/or docker-compose.yml files are involved, please paste their content as “preformatted text”.