I'd go even farther and say that the main useful feature of docker is the image layering. Even the resource isolation has been available with LXC and cgroups for a while now.
But docker certainly has a nice way of letting you use all these features in a friendly package. It's often not the most original things that are the most groundbreaking, sometimes it's when something comes along and takes all the parts you already have and puts them all together in a useful way.
But docker certainly has a nice way of letting you use all these features in a friendly package. It's often not the most original things that are the most groundbreaking, sometimes it's when something comes along and takes all the parts you already have and puts them all together in a useful way.