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¶etcdis a distributed data store, which is used in particular for the persistent storage of API Server.For more information, see etcd.io.
- Environment¶
An Environment is a namespace or group of namespaces with specific labels containing one or more Solutions. It allows to run multiple instances of a Solution on the same cluster, without collision between them.
- 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.
- Loki¶
Loki is a log aggregation system designed to be cost-effective, only indexing metadata (labels).
For more details, see Loki documentation.
- memberlist¶
memberlist is a Go library that manages cluster membership and member failure detection using a gossip based protocol. memberlist is eventually consistent but converges quickly on average.
- 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.
- Operator¶
A Kubernetes operator is an application-specific controller that extends the functionality of the Kubernetes API to create, configure, and manage instances of complex applications.
See also the official Kubernetes documentation for Operator.
- 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¶kubectlis a CLI interface for interacting with a Kubernetes cluster.See also the official Kubernetes documentation for
kubectl.