.. glossary::
Alertmanager
The Alertmanager is a service for handling alerts sent by client
applications, such as :term:`Prometheus`.
See also the official Prometheus documentation for
`Alertmanager <https://prometheus.io/docs/alerting/alertmanager/>`_.
API Server
``kube-apiserver``
The Kubernetes API Server validates and configures data for the Kubernetes
objects that make up a cluster, such as :term:`Nodes <Node>` or
:term:`Pods <Pod>`.
|see K8s docs|
`kube-apiserver <https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/>`_.
Bootstrap
Bootstrap node
The Bootstrap node is the first machine on which MetalK8s is installed,
and from where the cluster will be deployed to other machines. It also
serves as the entrypoint for upgrades of the cluster.
Controller Manager
``kube-controller-manager``
The Kubernetes controller manager embeds the core control loops shipped
with Kubernetes, which role is to watch the shared state from
:term:`API Server` and make changes to move the current state towards
the desired state.
|see K8s docs|
`kube-controller-manager <https://kubernetes.io/docs/reference/command-line-tools-reference/kube-controller-manager/>`_.
``etcd``
``etcd`` is a distributed data store, which is used in particular for the
persistent storage of :term:`API Server`.
For more information, see `etcd.io <https://etcd.io>`_.
Kubeconfig
A configuration file for :term:`kubectl`, which includes authentication
through embedded certificates.
|see K8s docs|
`kubeconfig <https://kubernetes.io/docs/concepts/configuration/organize-cluster-access-kubeconfig/>`_.
Kubelet
The kubelet is the primary "node agent" that runs on each cluster node.
|see K8s docs|
`https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet/`
Node
A Node is a Kubernetes worker machine - either virtual or physical.
A Node contains the services required to run :term:`Pods <Pod>`.
|see K8s docs|
`Nodes <https://kubernetes.io/docs/concepts/architecture/nodes/>`_.
Node manifest
The YAML file describing a :term:`Node`.
|see K8s docs|
`Nodes management <https://kubernetes.io/docs/concepts/architecture/nodes/#management>`_.
Pod
A Pod is a group of one or more containers sharing storage and network
resources, with a specification of how to run these containers.
|see K8s docs|
`Pods <https://kubernetes.io/docs/concepts/workloads/pods/pod/>`_.
Prometheus
Prometheus serves as a time-series database, and is used in MetalK8s as
the storage for all metrics exported by applications, whether being
provided by the cluster or installed afterwards.
For more details, see `prometheus.io <https://prometheus.io>`_.
SaltAPI
SaltAPI is an HTTP service for exposing operations to perform with a
:term:`Salt Master`. The version deployed by MetalK8s is configured to
use the cluster authentication/authorization services.
|see Salt docs|
`SaltAPI <https://docs.saltstack.com/en/latest/ref/netapi/all/salt.netapi.rest_cherrypy.html#a-rest-api-for-salt>`_.
Salt Master
The Salt Master is a daemon responsible for orchestrating infrastructure
changes by managing a set of :term:`Salt Minions <Salt Minion>`.
|see Salt docs|
`Salt Master <https://docs.saltstack.com/en/latest/topics/development/architecture.html#salt-master>`_.
Salt Minion
The Salt Minion is an agent responsible for operating changes on a system.
It runs on all MetalK8s nodes.
|see Salt docs|
`Salt Minion <https://docs.saltstack.com/en/latest/topics/development/architecture.html#salt-minion>`_.
Scheduler
``kube-scheduler``
The Kubernetes scheduler is responsible for assigning :term:`Pods <Pod>`
to specific :term:`Nodes <Node>` using a complex set of constraints and
requirements.
|see K8s docs|
`kube-scheduler <https://kubernetes.io/docs/reference/command-line-tools-reference/kube-scheduler/>`_.
Service
A Kubernetes Service is an abstract way to expose an application running
on a set of :term:`Pods <Pod>` as a network service.
|see K8s docs|
`Services <https://kubernetes.io/docs/concepts/services-networking/service/>`_.
Taint
Taints are a system for Kubernetes to mark :term:`Nodes <Node>` as
reserved for a specific use-case. They are used in conjunction with
:term:`tolerations <Toleration>`.
|see K8s docs|
`taints and tolerations <https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/>`_.
Toleration
Tolerations allow to mark :term:`Pods <Pod>` as schedulable for all
:term:`Nodes <Node>` matching some *filter*, described with
:term:`taints <Taint>`.
|see K8s docs|
`taints and tolerations <https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/>`_.
``kubectl``
|kubectl| is a CLI interface for interacting with a Kubernetes cluster.
|see K8s docs| |kubectl|_.