For many people, DevOps and infrastructure as code are synonymous. However, I am usually quick to point out the other moving parts that need to be managed. There is more to DevOps than infrastructure as code. Once the infrastructure is in place we need to do something with it. Application deployments, database updates, static content deployments, application configuration, middleware configuration, all of these things come into play after the infrastructure is in place.
There are many excellent applications for managing your infrastructure; tools such as Chef and Puppet obviously come to mind (they are easily the most popular). These types of tools are perfect for making changes across multiple servers, and making sure your infrastructure is in sync. They are also great for taking newly spun up virtual machines and making them identical the other servers in your environment.
Infrastructure is only part of the entire stack, and honestly it is not the most volatile part. New machines requiring infrastructure may be added daily but once the infrastructure is in place it tends to change less often than other components of the stack. For example, the middleware configuration, the applications, and the application configuration all change much more frequently than the infrastructure. Managing these changes is a crucial aspect of DevOps.
In the image above, the lowest layers can be handled by a number of tools. These layers are typically handled by the major IaaS providers (Amazon EC2, Rackspace, and others), which involve provisioning of the servers, as well as the OS and the OS configuration. Another great solution is to use Tereraform or uProvision to handle the provisioning. These tools enable companies to build an internal PaaS offering to allow teams to automatically spin up servers and make them available for deployment.
The middleware layers have a handful of solutions for automation. Some companies include this configuration in the base image of their virtual machines. Another popular option is using any of the “infrastructure as code” tools mentioned above. These types of configurations can even be managed as part of your application deployment in an application deployment automation (ADA) tool such as uDeploy.
The application, and the application configuration can change multiple times a day in any continuous delivery environment. Often it may only be the configuration itself (and not the binaries) that need to be deployed. uDeploy is designed to not only automate the deployment of the application but also provide visibility into which versions of changes have been applied and where.