Welcome back, in this lesson I'll be presenting an overview of Ansible. I'll cover what it is, some of its common use cases, and how it compares to other configuration management tools.

So let's start out by talking about what it is. Ansible is basically an automation engine, which is a rather simple description for something that's so powerful. It allows you to specify the tasks that you want to run on one or more servers in a fairly simple format. Ansible uses the YAML syntax. If you're not familiar with YAML it's a human friendly data serialisation format, which I'll cover more in depth later in the course.

With Ansible you can provision environments. You can configure your operating systems, you can deploy applications, you can even perform compliance checks, and these are just a few of the common use cases.

Let's go through these each a bit more. If your application requires infrastructure to support it, someone needs to set that up, and if you could automate it you'd save a lot of time and effort. Ansible allows you to specify how your infrastructure should look and it will create it for you. So if you're using a Cloud platform such as AWS, and you need auto scaling groups and RDS database, a load balancer and everything in between you could automate the creation and set up with Ansible.

If you're using virtual machines then you'll likely need to be configuring the operating system of those VMs, and that's another area that Ansible can help with. It allows you to specify the state that services and settings should be in, and it takes care of making sure that happens. For example, you could ensure that the Apache2 service is running. You could also ensure that a service such as Telnet is not running.

Another common use case is for application deployment, which Ansible makes fairly easy. You can specify the individual tasks that are required to deploy your app, and Ansible will execute them, and it will let you know the status of each task.

For example, you could have one task to download your application artifact, another to install it, and so on. And when Ansible executes these task it tells you if the task is changed since the last execution, you could also use Ansible for compliance checks. You can create tasks to do things such as setting firewall rules, enable and disable services, etcetera, and because Ansible is idempotent you can run the tasks as often as needed and report on the changes.

Idempotency means that the tasks are only run if the state you specify isn't currently met. An example of idempotency would be if you have a task that installs MySQL the first time it runs on a new server it will install MySQL the next time you run it nothing will happen, because MySQL is already installed.

Ansible isn't the only option when it comes to IT automation, there are quite a few tools out there that accomplish the same thing in different ways, and two popular options are Chef and Puppet. Ansible is a bit different than both of these in that it doesn't require an agent to be installed on the system that you're going to configure, however, it does require Python on any Linux servers you want to manage and PowerShell on any Windows servers.

Ansible uses the YAML syntax as we've mentioned, where Chef and Puppet use a Ruby Domain Specific Language, though Puppet also offers its own syntax that you can use, and none of these differences make either one intrinsically better. All three options are great tools and which one you select will come down to the features they support and the ease of use for your specific team. If your team already has Python skills then using Ansible may be a good option, because Ansible is written in Python and if your team is already familiar with it then custom development becomes easier.

Okay let's wrap up the lesson here. In the next lesson I'll run through the high level terms and concepts of Ansible. So if you're ready to keep learning then let's get started in the next lesson.