What are some of the tools that we can use to keep our containers the way we have set them up? How do we ensure that they stay the way we want them to? How do we ensure that if they do drift off or things change on them, we are able to put them back in place to where we want them to be? Let's see how we can achieve that.
Kubernetes is an open source project that was developed by Google to help with the automating deployment of your containers as well as scaling and the operations of your containers, not only on one host, but across multiple hosts. Kubernetes has been set to work on almost every environment that can be imagined, from locally in a Vagrant or VMware environment to cloud solutions such as AWS or Microsoft Azure. There will be some terminology that will need to be learned beyond the Docker terms, but if you understand how Docker operates, learning the Kubernetes terminology will come naturally. For example, instead of hosts, Kubernetes calls them pods. Kubernetes uses a single master node to control all its pods. The documentation can provide a lot more information including examples on how to administer your pods, set up pod clusters, and much more.
More information on Kubernetes can be found at http://kubernetes.io.
The reason we are focusing on Chef in this section is that AWS uses it as part of one of the solutions that they offer—in the form of OpsWorks. OpsWorks allows you to set up and use Chef to automate not only your Docker containers, but also other aspects of your AWS environment. I have personally set up and used Chef to do a lot of system automation throughout my personal environments. With that being said, Chef can be a little tricky at first to learn how to set up the server and client environments. There is a steep learning curve at first as with almost any configuration management system, but Chef does seem to have a little bit of a larger one with respect to all the moving pieces that are involved with the server environment and setup.
I wanted to draw focus to Chef though because if you are going to be viewing your environment within AWS, it might be a good idea to use Chef since it does offer it as a service within AWS. OpsWorks allows you to easily set up and control your environments as well as use their built-in Chef cookbooks. You can learn more about Chef at http://chef.io.
Some other solutions that are worth checking out or even use, if you already have the setup, to manage your Docker environment are:
- Puppet (http://puppetlabs.com)
- Ansible (http://www.ansible.com/)
- SaltStack (http://saltstack.com/)