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Update pods user guide to reflect StatefulSet changes

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Janet Kuo 2016-11-17 16:13:30 -08:00 committed by Devin Donnelly
parent 02a90c0b70
commit 3f86c70cd6
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docs/user-guide/pods/index.md
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@ -135,9 +135,9 @@ simplified management.
## Durability of pods (or lack thereof)
Pods aren't intended to be treated as durable [pets](https://blog.engineyard.com/2014/pets-vs-cattle). They won't survive scheduling failures, node failures, or other evictions, such as due to lack of resources, or in the case of node maintenance.
Pods aren't intended to be treated as durable entities. They won't survive scheduling failures, node failures, or other evictions, such as due to lack of resources, or in the case of node maintenance.
In general, users shouldn't need to create pods directly. They should almost always use controllers (e.g., [replication controller](/docs/user-guide/replication-controller/)), even for singletons. Controllers provide self-healing with a cluster scope, as well as replication and rollout management.
In general, users shouldn't need to create pods directly. They should almost always use controllers (e.g., [Deployments](/docs/user-guide/deployments/)), even for singletons. Controllers provide self-healing with a cluster scope, as well as replication and rollout management.
The use of collective APIs as the primary user-facing primitive is relatively common among cluster scheduling systems, including [Borg](https://research.google.com/pubs/pub43438.html), [Marathon](https://mesosphere.github.io/marathon/docs/rest-api.html), [Aurora](http://aurora.apache.org/documentation/latest/configuration-reference/#job-schema), and [Tupperware](http://www.slideshare.net/Docker/aravindnarayanan-facebook140613153626phpapp02-37588997).
@ -150,8 +150,9 @@ Pod is exposed as a primitive in order to facilitate:
* clean composition of Kubelet-level functionality with cluster-level functionality — Kubelet is effectively the "pod controller"
* high-availability applications, which will expect pods to be replaced in advance of their termination and certainly in advance of deletion, such as in the case of planned evictions, image prefetching, or live pod migration [#3949](http://issue.k8s.io/3949)
There is new first-class support for stateful pods with the [StatefulSet](/docs/concepts/controllers/statefulsets/) controller (currently in beta). The feature was alpha in 1.4 and was called [PetSet](/docs/user-guide/petset/). For prior versions of Kubernetes, best practice for having stateful pods is to create a replication controller with `replicas` equal to `1` and a corresponding service.
There is new first-class support for stateful pods with the [StatefulSet](/docs/concepts/controllers/statefulsets/) controller (currently in beta). The feature was alpha in 1.4 and was called [PetSet](/docs/user-guide/petset/). For prior versions of Kubernetes, best practice for having stateful pods is to create a replication controller with `replicas` equal to `1` and a corresponding service, see [this MySQL deployment example](/docs/tutorials/stateful-application/run-stateful-application/).
*TODO: link to Tutorial: Running a VM-style workload using StatefulSet*
## Termination of Pods
@ -177,6 +178,8 @@ Force deletion of a pod is defined as deletion of a pod from the cluster state a
Force deletions can be potentially dangerous for some pods and should be performed with caution. In case of StatefulSet pods, please refer to [this](/docs/tasks/stateful-sets/deleting-pods/).
*TODO: link to Task: Force Deleting a Pod*
## Privileged mode for pod containers
From kubernetes v1.1, any container in a pod can enable privileged mode, using the `privileged` flag on the `SecurityContext` of the container spec. This is useful for containers that want to use linux capabilities like manipulating the network stack and accessing devices. Processes within the container get almost the same privileges that are available to processes outside a container. With privileged mode, it should be easier to write network and volume plugins as separate pods that don't need to be compiled into the kubelet.