Orchestration

One solution to making the installation and management of Ceph easier is to use an orchestration tool. There are several tools available, such as Puppet, Chef, Salt, and Ansible, all of which have Ceph modules available. If you are already using an orchestration tool in your environment, then it would be recommended that you stick to using that tool. For the purposes of this book, Ansible will be used; this is for a number of reasons:

• It's the favored deployment method of Red Hat, who are the owners of both the Ceph and Ansible projects
• It has a well-developed and mature set of Ceph roles and playbooks
• Ansible tends to be easier to learn if you have never used an orchestration tool before
• It doesn't require a central server to be set up, which means demonstrations are more focused on using the tool rather than installing it

All tools follow the same principle of where you provide them with an inventory of hosts and a set of tasks to be carried out on the hosts. These tasks often reference variables that allows customization of the task at runtime. Orchestration tools are designed to be run on a schedule so that if for any reason the state or configuration of a host changes, it will be correctly changed back to the intended state during the next run.

Another advantage of using orchestration tools is documentation. Although they are not a replacement for good documentation, the fact that they clearly describe your environment including roles and configuration options, means that your environment starts to become self-documenting. If you ensure that any installations or changes are carried out via your orchestration tool, then the configuration file of the orchestration tool will clearly describe the current state of your environment. If this is combined with something like a git repository to store the orchestration configuration, you have the makings of a change control system. This is covered in more detail later in this chapter. The only disadvantages are around the extra time it takes to carry out the initial setup and configuration of the tool.

So, using an orchestration tool, not only do you get a faster and less error-prone deployment, you also get documentation and change management for free. If you haven't got the hint by now, this is something you should really be looking at.