mirror of
https://github.com/k3s-io/kubernetes.git
synced 2025-10-31 05:40:42 +00:00
112 lines
4.8 KiB
Markdown
112 lines
4.8 KiB
Markdown
# Well-Known Labels, Annotations and Taints
|
|
|
|
Kubernetes reserves all labels and annotations in the kubernetes.io namespace. This document describes
|
|
the well-known kubernetes.io labels and annotations.
|
|
|
|
This document serves both as a reference to the values, and as a coordination point for assigning values.
|
|
|
|
**Table of contents:**
|
|
<!-- BEGIN MUNGE: GENERATED_TOC -->
|
|
|
|
- [Well-Known Labels, Annotations and Taints](#well-known-labels-annotations-and-taints)
|
|
- [beta.kubernetes.io/arch](#betakubernetesioarch)
|
|
- [beta.kubernetes.io/os](#betakubernetesioos)
|
|
- [kubernetes.io/hostname](#kubernetesiohostname)
|
|
- [beta.kubernetes.io/instance-type](#betakubernetesioinstance-type)
|
|
- [failure-domain.beta.kubernetes.io/region](#failure-domainbetakubernetesioregion)
|
|
- [failure-domain.beta.kubernetes.io/zone](#failure-domainbetakubernetesiozone)
|
|
|
|
<!-- END MUNGE: GENERATED_TOC -->
|
|
|
|
|
|
## beta.kubernetes.io/arch
|
|
|
|
Example: `beta.kubernetes.io/arch=amd64`
|
|
|
|
Used on: Node
|
|
|
|
Kubelet populates this with `runtime.GOARCH` as defined by Go. This can be handy if you are mixing arm and x86 nodes,
|
|
for example.
|
|
|
|
## beta.kubernetes.io/os
|
|
|
|
Example: `beta.kubernetes.io/os=linux`
|
|
|
|
Used on: Node
|
|
|
|
Kubelet populates this with `runtime.GOOS` as defined by Go. This can be handy if you are mixing operating systems
|
|
in your cluster (although currently Linux is the only OS supported by kubernetes).
|
|
|
|
## kubernetes.io/hostname
|
|
|
|
Example: `kubernetes.io/hostname=ip-172-20-114-199.ec2.internal`
|
|
|
|
Used on: Node
|
|
|
|
Kubelet populates this with the hostname. Note that the hostname can be changed from the "actual" hostname
|
|
by passing the `--hostname-override` flag to kubelet.
|
|
|
|
## beta.kubernetes.io/instance-type
|
|
|
|
Example: `beta.kubernetes.io/instance-type=m3.medium`
|
|
|
|
Used on: Node
|
|
|
|
Kubelet populates this with the instance type as defined by the `cloudprovider`. It will not be set if
|
|
not using a cloudprovider. This can be handy if you want to target certain workloads to certain instance
|
|
types, but typically you want to rely on the kubernetes scheduler to perform resource-based scheduling,
|
|
and you should aim to schedule based on properties rather than on instance types (e.g. require a GPU, instead
|
|
of requiring a `g2.2xlarge`)
|
|
|
|
|
|
## failure-domain.beta.kubernetes.io/region
|
|
|
|
See [failure-domain.beta.kubernetes.io/zone](#failure-domainbetakubernetesiozone)
|
|
|
|
## failure-domain.beta.kubernetes.io/zone
|
|
|
|
Example:
|
|
|
|
`failure-domain.beta.kubernetes.io/region=us-east-1`
|
|
|
|
`failure-domain.beta.kubernetes.io/zone=us-east-1c`
|
|
|
|
Used on: Node, PersistentVolume
|
|
|
|
On the Node: Kubelet populates this with the zone information as defined by the `cloudprovider`. It will not be set if
|
|
not using a `cloudprovider`, but you should consider setting it on the nodes if it makes sense in your topology.
|
|
|
|
On the PersistentVolume: The `PersistentVolumeLabel` admission controller will automatically add zone labels to PersistentVolumes,
|
|
on GCE and AWS.
|
|
|
|
Kubernetes will automatically spread the pods in a replication controller or service across nodes in a single-zone
|
|
cluster (to reduce the impact of failures.) With multiple-zone clusters, this spreading behaviour is extended
|
|
across zones (to reduce the impact of zone failures.) This is achieved via SelectorSpreadPriority.
|
|
|
|
This is a best-effort placement, and so if the zones in your cluster are heterogeneous (e.g. different numbers of nodes,
|
|
different types of nodes, or different pod resource requirements), this might prevent equal spreading of
|
|
your pods across zones. If desired, you can use homogenous zones (same number and types of nodes) to reduce
|
|
the probability of unequal spreading.
|
|
|
|
The scheduler (via the VolumeZonePredicate predicate) will also ensure that pods that claim a given volume
|
|
are only placed into the same zone as that volume, as volumes cannot be attached across zones.
|
|
|
|
|
|
The actual values of zone and region don't matter, and nor is the meaning of the hierarchy rigidly defined. The expectation
|
|
is that failures of nodes in different zones should be uncorrelated unless the entire region has failed. For example,
|
|
zones should typically avoid sharing a single network switch. The exact mapping depends on your particular
|
|
infrastructure - a three-rack installation will choose a very different setup to a multi-datacenter configuration.
|
|
|
|
If `PersistentVolumeLabel` does not support automatic labeling of your PersistentVolumes, you should consider
|
|
adding the labels manually (or adding support to `PersistentVolumeLabel`), if you want the scheduler to prevent
|
|
pods from mounting volumes in a different zone. If your infrastructure doesn't have this constraint, you don't
|
|
need to add the zone labels to the volumes at all.
|
|
|
|
|
|
|
|
|
|
|
|
<!-- BEGIN MUNGE: GENERATED_ANALYTICS -->
|
|
[]()
|
|
<!-- END MUNGE: GENERATED_ANALYTICS -->
|