We are currently running Red Hat 5. But I saw documentation that says docker is only supported on Red Hat 7. So we have to upgrade to Red Hat 7 or we can't use docker at all on RHEL 5? Alternatively we can consider to switch to Ubuntu.
How do others solve the similar issue?
You will need to upgrade from RHEL5 to use Docker.
The official Docker release deprecated RHEL6 support from 1.7 (and inadvertently broke it in 1.7.0 but fixed in 1.7.1). Support for RHEL6 was dropped in Docker 1.8. Since then, a RHEL7 based distro with a 3.10+ kernel has been required.
There is a docker-io-1.7.1-2 package available on EPEL for RHEL6.5+ based distros. RHEL6 runs an older 2.6 kernel with back ported fixes so docker can work. This kernel must be at 2.6.32-431 or higher.
RHEL doesn't support AUFS which is the most commonly used Docker storage driver. By default RHEL uses a loopback storage driver which is not production ready. The EPEL packages provide docker-storage-setup to setup thin provisioned LVM. You need to do this setup manually if you want to run the docker.com packages.
Personally I would recommend going with a recent debian based distribution running the official docker packages for timely updates. If you are on EC2, Amazons AMI will do nicely though.
