Glossary

Alertmanager

The Alertmanager is a service for handling alerts sent by client applications, such as Prometheus.

See also the official Prometheus documentation for Alertmanager.

API Server
kube-apiserver

The Kubernetes API Server validates and configures data for the Kubernetes objects that make up a cluster, such as Nodes or Pods.

See also the official Kubernetes documentation for 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.

ConfigMap

A ConfigMap is a Kubernetes object that allows one to store general configuration information such as environment variables in a key-value pair format. ConfigMaps can only be applied to namespaces and once created, they can be updated automatically without the need of restarting containers that depend on it.

See also the official Kubernetes documentation for ConfigMap.

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 API Server and make changes to move the current state towards the desired state.

See also the official Kubernetes documentation for kube-controller-manager.

etcd

etcd is a distributed data store, which is used in particular for the persistent storage of API Server.

For more information, see etcd.io.

Grafana

Grafana is a service for analysing and visualizing metrics scraped by Prometheus.

For more information, see Grafana.

Kubeconfig

A configuration file for kubectl, which includes authentication through embedded certificates.

See also the official Kubernetes documentation for kubeconfig.

Kubelet

The kubelet is the primary “node agent” that runs on each cluster node.

See also the official Kubernetes documentation for kubelet.

Kube-state-metrics

The kube-state-metrics service listens to the Kubernetes API server and generates metrics about the state of the objects.

See also the official Kubernetes documentation for kube-state-metrics.

Namespace

A Namespace is a Kubernetes abstraction to support multiple virtual clusters backed by the same physical cluster, providing a scope for resource names.

See also the official Kubernetes documentation for namespaces.

Node

A Node is a Kubernetes worker machine - either virtual or physical. A Node contains the services required to run Pods.

See also the official Kubernetes documentation for Nodes.

Node manifest

The YAML file describing a Node.

See also the official Kubernetes documentation for 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 also the official Kubernetes documentation for Pods.

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.

Prometheus Node-exporter

The Prometheus node-exporter is an exporter for exposing hardware and OS metrics read from the Linux Kernel. Users can typically obtain the following metrics; cpu, memory, filesystem for each Kubernetes node.

or more details, see prometheus node-exporter.

SaltAPI

SaltAPI is an HTTP service for exposing operations to perform with a Salt Master. The version deployed by MetalK8s is configured to use the cluster authentication/authorization services.

See also the official SaltStack documentation for SaltAPI.

Salt Master

The Salt Master is a daemon responsible for orchestrating infrastructure changes by managing a set of Salt Minions.

See also the official SaltStack documentation for Salt Master.

Salt Minion

The Salt Minion is an agent responsible for operating changes on a system. It runs on all MetalK8s nodes.

See also the official SaltStack documentation for Salt Minion.

Scheduler
kube-scheduler

The Kubernetes scheduler is responsible for assigning Pods to specific Nodes using a complex set of constraints and requirements.

See also the official Kubernetes documentation for kube-scheduler.

Secret

Kubernetes Secrets let you store and manage sensitive information, such as passwords, OAuth tokens, and SSH keys.

See also the official Kubernetes documentation for Secrets.

Service

A Kubernetes Service is an abstract way to expose an application running on a set of Pods as a network service.

See also the official Kubernetes documentation for Services.

Taint

Taints are a system for Kubernetes to mark Nodes as reserved for a specific use-case. They are used in conjunction with tolerations.

See also the official Kubernetes documentation for taints and tolerations.

Toleration

Tolerations allow to mark Pods as schedulable for all Nodes matching some filter, described with taints.

See also the official Kubernetes documentation for taints and tolerations.

kubectl

kubectl is a CLI interface for interacting with a Kubernetes cluster.

See also the official Kubernetes documentation for kubectl.