The more you understand about OpenStack, how it is organized and architected, the more successful you will be at troubleshooting it. In this section, we provide you with a strong foundation of understanding about OpenStack. Throughout the book, we will build on this foundation, going deeper into each project as we encounter them in future chapters. To start the journey, we will introduce you to some of the projects that are commonly deployed in an OpenStack cluster. It's worth pointing out that we won't cover every OpenStack project, but we will attempt to adequately cover each of the commonly deployed projects.
Keystone is the OpenStack Identity service. It is responsible for authentication and is involved in authorization for an OpenStack cluster. Keystone is also responsible for service discovery, allowing users to see which services are available in a cluster. A user-initiated request will typically flow through Keystone; so, learning to troubleshoot this service is a wise investment.
Glance is the OpenStack Image service. Glance is primarily responsible for image registration and storage. As an example, compute instances can be created based on machine images. These images are typically stored through and retrieved via Glance.
Neutron is the OpenStack Networking service. Networking is hard, and it is no different in OpenStack. Neutron is responsible for abstracting the network-related functionality in OpenStack. This is an area where many operators may run into trouble. Learning how to skillfully troubleshoot Neutron will serve you well as an OpenStack administrator.
Nova is the OpenStack Compute service. Nova provides compute instances in an OpenStack cloud. This is one of the largest OpenStack projects and one of the oldest. Nova is used heavily in an OpenStack cloud, and it is critical that troubleshooters understand this project, its concepts, components, and architecture.
Cinder is the project that provides block storage services for OpenStack. Cinder abstracts and provides access to several backend storage options. Compute instances will often receive their block storage via the Cinder service.
Swift is the OpenStack Object Storage service. Swift provides object-based storage, which is accessed via an API. Unlike Cinder, Swift does not expose block-level storage, but it does offer a system that allows you to store petabytes of data on a cluster that is built on commodity hardware.
The OpenStack Orchestration service is named Heat. Heat allows users to leverage a declarative template language to describe, build, and deploy OpenStack resources. It is designed to allow users to manage the entire life cycle of their cloud resources.
Ceilometer is the OpenStack Telemetry service, and it is responsible for collecting utilization measurements from physical and virtual resources in an OpenStack cloud.
The OpenStack dashboard is named Horizon. Horizon provides the graphical user interface for OpenStack. It relies on the OpenStack APIs to present much of this functionality. It is an extremely useful tool when troubleshooting the APIs or OpenStack functionality in general.
Oslo is the OpenStack project that contains the shared Python libraries that are leveraged across all projects. Examples of these include code that supports messaging, command-line programs, configuration, and logging.
One of the strengths of the OpenStack community is that it treats documentation as a first-class citizen. In the community, documentation is just as important as code. The documentation project is structured like the others and receives a good amount of exposure and attention.
In addition to the these projects, there are several other popular projects worth mentioning. These projects include the following:
While Nova typically handles the provisioning of virtual machines, with Ironic, users can provision physical hardware in a cloudy way. The Ironic driver allows you to deploy bare metal hardware in a similar fashion to the way you deploy virtual machines.
Magnum is a project designed to allow users to manage application containers in OpenStack. This allows container orchestration engines, such as Docker and Kubernetes, to be leveraged through OpenStack.
Trove is an OpenStack service that provides cloud databases. The Trove service supports the provisioning of both relational and non-relational databases.
Barbican is a service that facilitates the management, provisioning, and storage of secrets. Secrets include things such as passwords, encryption keys, and certificates.
Congress provides a policy as a service for OpenStack. The aim of the project is to provide a framework for regulatory compliance and governance across cloud services. Its responsibility is policy enforcement.
Designate provides DNS as a service. This service provides zone and record management as well as support for multiple nameservers.
These are just some of the many projects under the Big Tent of OpenStack. New projects with the promise of a new functionality are created regularly. As these projects gain more and more adoption, the chance that you will need to troubleshoot them increases.