Glossary

The following sections offer definitions for Anthos GKE on-prem (GKE on-prem) and Kubernetes terms.

You can also refer to:

A

Admin cluster

A cluster which creates user clusters and manages their control planes. All API calls to and from GKE on-prem are handled by the admin control plane that runs in the admin cluster.

Admin control plane

The control plane running in the admin cluster.

This control plane specifically handles all Kubernetes API calls to and from GKE on-prem: when an API call is made, it hit the admin control plane, then routes to its intended destination. Manages the full lifecycle of user clusters, including creation, upgrading, and deletion. It runs services which interact with vSphere and the Connect Agent.

C

CLI

Acronym for "command line interface."

Cluster

Might refer to:

  • vSphere cluster, a set of vSphere virtual machines.
  • GKE on-prem cluster. From the Kubernetes standardized glossary: "A set of machines, called nodes, that run containerized applications managed by Kubernetes." In GKE on-prem, there are admin clusters and user clusters.

Configuration file

Also known as "config file." Might refer to:

Not to be confused with a Kubernetes ConfigMap resource.

Control plane

A cluster's controlling unit, consisting of a set of components that schedule and manage workloads, communicate with clusters, and ensure that clusters are functioning. Control planes include the etcd key-value datastore, the Kubernetes API server, the scheduler, and the controller manager. Also refer to the Kubernetes documentation for Kubernetes control plane.

D

Data center

Might refer to:

  • The physical location of a facility housing networked computers and storage devices.
  • The virtual vCenter Datacenter. From the VMware documentation: "a container for all the inventory objects required to complete a fully functional environment for operating virtual machines."

Deployment

See Deployment.

Distributed Resource Scheduler (DRS)

VMware utility that dynamically distributes computing capacity for VMs across groups of physical hosts.

G

gkectl

The command-line interface (CLI) to GKE on-prem. You use gkectl to create and manage GKE on-prem clusters, and to diagnose issues with clusters.

H

High availability (HA)

Might refer to:

  • vSphere HA, a feature that automatically restarts VMs on a available host when a VM fails.
  • The high availability concept, describing a computing system's high resilience to outages.

host

A physical machine running in a data center. Also called a server. Virtual machines are deployed to hosts.

I

Island Mode

GKE on-prem does not create an overlay network for cluster networking. Instead, it creates a node-to-node mesh using BGP so that Pods can reach each other within the cluster using the existing underlay network. But this network is not directly reachable from outside the cluster, as the routes are only announced between the nodes that make up the cluster. This is configuration is called Island Mode networking as it can be thought of an island within the existing on-premises network.

M

Machine

Might refer to:

Manifest

Might refer to:

  • A Kubernetes YAML configuration file.
  • The specification of

N

Node

Might refer to:

  • A worker machine running in a Kubernetes cluster. A cluster is composed of multiple nodes.

  • A vSphere virtual machine in a GKE on-prem cluster. Also called a "VM" or "machine."

  • A Cluster API Node resource, which serves as a symbolic link to a worker machine in a Kubernetes cluster.

O

Object

Usually refers to a Kubernetes resource.

P

Pod

A Kubernetes object that runs a containerized workload. It is the smallest deployable unit of computing in Kubernetes. Pods are usually managed by another object, like a Deployment or StatefulSet. Also refer to the Kubernetes documentation for Pod.

R

Resource

Might refer to:

Resource pool

In GKE on-prem, this is simply a set of VMs in a vSphere cluster. Learn more about resource pools.

S

Service

A Kubernetes object that logically groups a set of Pods and defines a policy by which to access them. Also refer to the Kubernetes documentation for Service.

StatefulSet

A Kubernetes objects meant for stateful applications. Pods managed by a StatefulSet get a unique, persistent identity in their cluster. Also refer to the Kubernetes documentation for StatefulSet.

U

User cluster

A cluster where developers' Kubernetes workloads run. User clusters are managed by an admin cluster.

V

Virtual Machine File System (VMFS)

Cluster file system for ESXi.

vCenter

vSphere's web-based user interface for managing data center services. Provides a central view across ESXi hosts.

vSphere

VMware's suite of virtualization products that includes vCenter and ESXi.

vSphere Client

Also called vSphere Web Client, this is VMware's web-based management interface for vSphere which allows you to connect to vCenter Server.

Virtual machine (VM)

An emulation of a computer system with specific architecture and hardware specifications. Substitutes physical machine hardware. VMs are deployed to hosts—physical machines running in a datacenter. GKE on-prem creates and uses clusters of vSphere VMs to deploy GKE on-prem clusters.