Interacting with OpenStack

The power of OpenStack is in the REST API of each core service. These APIs can be publicly exposed and thus accessible from anywhere in the world with public internet access: a smartphone, a laptop on the coffee shop WiFi network, or remote office.

There are a variety of ways in which one can interact with OpenStack to create virtual resources from anywhere. As we work our way down these various methods, the amount of automation increases, allowing a software developer to easily create virtual resources and deploy applications on top of those resources with minimal user interaction. See Figure 1.5.

• Horizon dashboard (GUI): If you are new to OpenStack, this is the best place to begin your journey. You simply navigate to the Horizon URL via the web browser, enter your username and password, verify you are scoped to the proper project, and then proceed—creating instances, networks, and volumes with the click of a button. See Figure 1.4 for where the services are located upon first logging in. Because not all OpenStack service features are available via the Horizon dashboard, you will need to also interact with OpenStack services via the command-line interface to utilize additional functionality.

• Command-line interface (CLI): The OpenStack command line interface will unlock a majority of the OpenStack service features and can easily be installed on Windows, Mac, and Linux systems. For Linux gurus with Bash shell experience, the CLI is the tool of choice.
• Software development kit (SDK): Although the bash shell and OpenStack CLI combination are extremely powerful, SDKs provide more expressiveness. One example scenario: a developer hosting their popular application on OpenStack virtual infrastructure so that additional resources can be automatically provisioned when specific thresholds are met. Or, imagine an Android application that allows an organization's employees to create OpenStack resources with a few simple clicks of a button. Simply put, OpenStack SDKs allow you to programmatically interact with OpenStack services in the comfort of your favorite language. OpenStack SDKs are currently available in the following languages: C, C++, Closure, Erlang, Go, Java, JavaScript, .NET, Node.js, Perl, PHP, Python, and Ruby.
• Heat orchestration template (HOT): You can deploy Heat templates (similar to Amazon Web Service CloudFormation Blueprints) that utilize the OpenStack service APIs—creating OpenStack resources with the simple click of a button. The user defines their application by describing OpenStack resources in the template. The Heat templates provide maximum automation to the cloud user, deploying an entire application without manual creation of individual resources or dependencies. One can even check these into a version control system such as Git to easily track changes to the infrastructure.