magnum/doc/source/user/glossary.rst
Alexandra Settle 2153287a6d Fixing broken links
This also removes reference to the deprecated DevStack gate.
A few links have been removed, namely anything relating to
/elements/ as it doesn't appear to exist anymore and I cannot
find any reference to it. If anyone can point me in the right
direction, that would be appreciated.

Change-Id: Ie3fab1afc5b2958819b74c39a0e492fd7da5d6a3
Backports: stein rocky
Signed-off-by: Alexandra Settle <asettle@suse.com>
2019-09-12 14:29:00 +00:00

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.. _glossary:
========
Glossary
========
Magnum Terminology
~~~~~~~~~~~~~~~~~~
.. glossary::
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
~~~~~~~~~~~~~~~~~~~~~~
.. glossary::
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 <https://kubernetes.io/docs/concepts/workloads/pods/pod-overview/>`_ in
`Kubernetes Tasks`_ 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
<https://kubernetes.io/docs/tasks/run-application/rolling-update-replication-controller/>`_ in
the `Kubernetes Tasks`_ 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
<https://kubernetes.io/docs/concepts/services-networking/service/>`_ in
`Kubernetes Concepts`_ for more information.
.. _Kubernetes Tasks: https://kubernetes.io/docs/tasks/
.. _Kubernetes Concepts: https://kubernetes.io/docs/concepts/