While Docker has been built on top of well-established technologies such as Linux Containers (LXC), these have traditionally been difficult to configure and manage, especially for non-system administrators.

Docker removes almost all the barriers to entry, allowing everyone with a small amount of command-line experience to launch and manage their own container-based applications.

This has forced a lot of the supporting tools to also lower their barrier to entry. Software that once required careful planning to deploy, such as some of the monitoring tools we covered in this module, can now be deployed and configured in minutes rather than hours.

Docker is also a very fast-moving technology; while it has been considered production-ready for a while, new features are being added and existing features are improved with regular updates.

So far, in 2015, there have been 11 releases of Docker Engine; of these, only six have been minor updates that fix bugs, and the rest have all been major updates. Details of each release can be found in the project's Changelog, which can be found at https://github.com/docker/docker/blob/master/CHANGELOG.md.

Because of the pace of development of Docker, it is import that you also update any monitoring tools you deploy. This is not only to keep up with new features, but also to ensure that you don't loose any functionality due to changes in the way in which Docker works.

This attitude of updating monitoring clients/tools can be a bit of a change for some administrators who maybe in the past would have configured a monitoring agent on a server and then not thought about it again.