When docker installed according https://docs.docker.com/engine/installation/linux/rhel/ there is below error (on some RHEL 7 machines)
Loaded plugins: langpacks, product-id, search-disabled-repos, subscription-
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
You have enabled checking of packages via GPG keys. This is a good thing.
However, you do not have any GPG public keys installed. You need to download
the keys for packages you wish to install and install them.
You can do that by running the command:
rpm --import public.gpg.key
Alternatively you can specify the url to the key you would like to use
for a repository in the 'gpgkey' option in a repository section and yum
will install it for you.
For more information contact your distribution or package provider.
Problem repository: packages.docker.com_1.12_yum_repo_main_centos_7
The repository that was added according installation documentation is bad.
Here is the bad command for documentation:
sudo yum-config-manager \ --add-repo \ https://docs.docker.com/engine/installation/linux/repo_files/centos/docker.repo
Remove the repository and try again.
Delete the description from /etc/yum.conf or the file from /etc/yum.repos.d/