Convert site to Hugo (#8316)
This commit converts content and layout to use Hugo.
This commit is contained in:
Bjørn Erik Pedersen
committed by
k8s-ci-robot
k8s-ci-robot
parent
7745f0e0c5
commit
7f3b633aa0
@@ -0,0 +1,112 @@
|
||||
---
|
||||
reviewers:
|
||||
- lavalamp
|
||||
title: Kubernetes Components
|
||||
content_template: templates/concept
|
||||
---
|
||||
|
||||
{{% capture overview %}}
|
||||
This document outlines the various binary components needed to
|
||||
deliver a functioning Kubernetes cluster.
|
||||
{{% /capture %}}
|
||||
|
||||
{{% capture body %}}
|
||||
## Master Components
|
||||
|
||||
Master components provide the cluster's control plane. Master components make global decisions about the
|
||||
cluster (for example, scheduling), and detecting and responding to cluster events (starting up a new pod when a replication controller's 'replicas' field is unsatisfied).
|
||||
|
||||
Master components can be run on any machine in the cluster. However,
|
||||
for simplicity, set up scripts typically start all master components on
|
||||
the same machine, and do not run user containers on this machine. See
|
||||
[Building High-Availability Clusters](/docs/admin/high-availability/) for an example multi-master-VM setup.
|
||||
|
||||
### kube-apiserver
|
||||
|
||||
{{< glossary_definition term_id="kube-apiserver" length="all" >}}
|
||||
|
||||
### etcd
|
||||
|
||||
{{< glossary_definition term_id="etcd" length="all" >}}
|
||||
|
||||
### kube-scheduler
|
||||
|
||||
{{< glossary_definition term_id="kube-scheduler" length="all" >}}
|
||||
|
||||
### kube-controller-manager
|
||||
|
||||
{{< glossary_definition term_id="kube-controller-manager" length="all" >}}
|
||||
|
||||
These controllers include:
|
||||
|
||||
* Node Controller: Responsible for noticing and responding when nodes go down.
|
||||
* Replication Controller: Responsible for maintaining the correct number of pods for every replication
|
||||
controller object in the system.
|
||||
* Endpoints Controller: Populates the Endpoints object (that is, joins Services & Pods).
|
||||
* Service Account & Token Controllers: Create default accounts and API access tokens for new namespaces.
|
||||
|
||||
### cloud-controller-manager
|
||||
|
||||
[cloud-controller-manager](/docs/tasks/administer-cluster/running-cloud-controller/) runs controllers that interact with the underlying cloud providers. The cloud-controller-manager binary is an alpha feature introduced in Kubernetes release 1.6.
|
||||
|
||||
cloud-controller-manager runs cloud-provider-specific controller loops only. You must disable these controller loops in the kube-controller-manager. You can disable the controller loops by setting the `--cloud-provider` flag to `external` when starting the kube-controller-manager.
|
||||
|
||||
cloud-controller-manager allows cloud vendors code and the Kubernetes core to evolve independent of each other. In prior releases, the core Kubernetes code was dependent upon cloud-provider-specific code for functionality. In future releases, code specific to cloud vendors should be maintained by the cloud vendor themselves, and linked to cloud-controller-manager while running Kubernetes.
|
||||
|
||||
The following controllers have cloud provider dependencies:
|
||||
|
||||
* Node Controller: For checking the cloud provider to determine if a node has been deleted in the cloud after it stops responding
|
||||
* Route Controller: For setting up routes in the underlying cloud infrastructure
|
||||
* Service Controller: For creating, updating and deleting cloud provider load balancers
|
||||
* Volume Controller: For creating, attaching, and mounting volumes, and interacting with the cloud provider to orchestrate volumes
|
||||
|
||||
## Node Components
|
||||
|
||||
Node components run on every node, maintaining running pods and providing the Kubernetes runtime environment.
|
||||
|
||||
### kubelet
|
||||
|
||||
{{< glossary_definition term_id="kubelet" length="all" >}}
|
||||
|
||||
### kube-proxy
|
||||
|
||||
[kube-proxy](/docs/admin/kube-proxy/) enables the Kubernetes service abstraction by maintaining
|
||||
network rules on the host and performing connection forwarding.
|
||||
|
||||
### Container Runtime
|
||||
|
||||
The container runtime is the software that is responsible for running containers. Kubernetes supports several runtimes: [Docker](http://www.docker.com), [rkt](https://coreos.com/rkt/), [runc](https://github.com/opencontainers/runc) and any OCI [runtime-spec](https://github.com/opencontainers/runtime-spec) implementation.
|
||||
|
||||
## Addons
|
||||
|
||||
Addons are pods and services that implement cluster features. The pods may be managed
|
||||
by Deployments, ReplicationControllers, and so on. Namespaced addon objects are created in
|
||||
the `kube-system` namespace.
|
||||
|
||||
Selected addons are described below, for an extended list of available addons please see [Addons](/docs/concepts/cluster-administration/addons/).
|
||||
|
||||
### DNS
|
||||
|
||||
While the other addons are not strictly required, all Kubernetes clusters should have [cluster DNS](/docs/concepts/services-networking/dns-pod-service/), as many examples rely on it.
|
||||
|
||||
Cluster DNS is a DNS server, in addition to the other DNS server(s) in your environment, which serves DNS records for Kubernetes services.
|
||||
|
||||
Containers started by Kubernetes automatically include this DNS server in their DNS searches.
|
||||
|
||||
### Web UI (Dashboard)
|
||||
|
||||
[Dashboard](/docs/tasks/access-application-cluster/web-ui-dashboard/) is a general purpose, web-based UI for Kubernetes clusters. It allows users to manage and troubleshoot applications running in the cluster, as well as the cluster itself.
|
||||
|
||||
### Container Resource Monitoring
|
||||
|
||||
[Container Resource Monitoring](/docs/tasks/debug-application-cluster/resource-usage-monitoring/) records generic time-series metrics
|
||||
about containers in a central database, and provides a UI for browsing that data.
|
||||
|
||||
### Cluster-level Logging
|
||||
|
||||
A [Cluster-level logging](/docs/concepts/cluster-administration/logging/) mechanism is responsible for
|
||||
saving container logs to a central log store with search/browsing interface.
|
||||
|
||||
{{% /capture %}}
|
||||
|
||||
|
||||
Reference in New Issue
Block a user