Glossary

Glossary

Magnum Terminology

Cluster (previously Bay)
A cluster is the construct in which Magnum launches container orchestration engines. After a cluster has been created the user is able to add containers to it either directly, or in the case of the Kubernetes container orchestration engine within pods - a logical construct specific to that implementation. A cluster is created based on a ClusterTemplate.
ClusterTemplate (previously BayModel)
A ClusterTemplate in Magnum is roughly equivalent to a flavor in Nova. It acts as a template that defines options such as the container orchestration engine, keypair and image for use when Magnum is creating clusters using the given ClusterTemplate.
Container Orchestration Engine (COE)
A container orchestration engine manages the lifecycle of one or more containers, logically represented in Magnum as a cluster. Magnum supports a number of container orchestration engines, each with their own pros and cons, including Docker Swarm, Kubernetes, and Mesos.
Labels
Labels is a general method to specify supplemental parameters that are specific to certain COE or associated with certain options. Their format is key/value pair and their meaning is interpreted by the drivers that uses them.
Cluster Drivers
A cluster driver is a collection of python code, heat templates, scripts, images, and documents for a particular COE on a particular distro. Magnum presents the concept of ClusterTemplates and clusters. The implementation for a particular cluster type is provided by the cluster driver. In other words, the cluster driver provisions and manages the infrastructure for the COE.

Kubernetes Terminology

Kubernetes uses a range of terminology that we refer to in this guide. We define these common terms for your reference:

Pod
When using the Kubernetes container orchestration engine, a pod is the smallest deployable unit that can be created and managed. A pod is a co-located group of application containers that run with a shared context. When using Magnum, pods are created and managed within clusters. Refer to the pods section in the Kubernetes User Guide for more information.
Replication controller
A replication controller is used to ensure that at any given time a certain number of replicas of a pod are running. Pods are automatically created and deleted by the replication controller as necessary based on a template to ensure that the defined number of replicas exist. Refer to the replication controller section in the Kubernetes User Guide for more information.
Service
A service is an additional layer of abstraction provided by the Kubernetes container orchestration engine which defines a logical set of pods and a policy for accessing them. This is useful because pods are created and deleted by a replication controller, for example, other pods needing to discover them can do so via the service abstraction. Refer to the services section in the Kubernetes User Guide for more information.
Creative Commons Attribution 3.0 License

Except where otherwise noted, this document is licensed under Creative Commons Attribution 3.0 License. See all OpenStack Legal Documents.