: A key/value pair that can hold large (compared to a Label), and possibly not human-readable data. Intended to store
non-identifying metadata associated with an object, such as provenance information. Not indexed.
**Image**
: A [Docker Image](https://docs.docker.com/userguide/dockerimages/). See [images](user-guide/images.md).
**Label**
: A key/value pair conveying user-defined identifying attributes of an object, and used to form sets of related objects, such as
pods which are replicas in a load-balanced service. Not intended to hold large or non-human-readable data. See [labels](user-guide/labels.md).
**Name**
: A user-provided name for an object. See [identifiers](user-guide/identifiers.md).
**Namespace**
: A namespace is like a prefix to the name of an object. You can configure your client to use a particular namespace,
so you do not have to type it all the time. Namespaces allow multiple projects to prevent naming collisions between unrelated teams.
**Pod**
: A collection of containers which will be scheduled onto the same node, which share and an IP and port space, and which
can be created/destroyed together. See [pods](user-guide/pods.md).
**Replication Controller**
: A _replication controller_ ensures that a specified number of pod "replicas" are running at any one time. Both allows
for easy scaling of replicated systems, and handles restarting of a Pod when the machine it is on reboots or otherwise fails.
**Resource**
: CPU, memory, and other things that a pod can request. See [compute resources](user-guide/compute-resources.md).
**Secret**
: An object containing sensitive information, such as authentication tokens, which can be made available to containers upon request. See [secrets](user-guide/secrets.md).
**Selector**
: An expression that matches Labels. Can identify related objects, such as pods which are replicas in a load-balanced
service. See [labels](user-guide/labels.md).
**Service**
: A load-balanced set of `pods` which can be accessed via a single stable IP address. See [services](user-guide/services.md).
**UID**
: An identifier on all Kubernetes objects that is set by the Kubernetes API server. Can be used to distinguish between historical
occurrences of same-Name objects. See [identifiers](user-guide/identifiers.md).
**Volume**
: A directory, possibly with some data in it, which is accessible to a Container as part of its filesystem. Kubernetes
Volumes build upon [Docker Volumes](https://docs.docker.com/userguide/dockervolumes/), adding provisioning of the Volume
directory and/or device. See [volumes](user-guide/volumes.md).
-[Kubernetes User Guide: Managing Applications](#kubernetes-user-guide:-managing-applications)
-[Quick walkthrough](#quick-walkthrough)
-[Thorough walkthrough](#thorough-walkthrough)
-[Concept guide](#concept-guide)
-[Further reading](#further-reading)
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The user guide is intended for anyone who wants to run programs and services on an existing Kubernetes cluster. Setup and administration of a Kubernetes cluster is described in the [Cluster Admin Guide](../../docs/admin/README.md). The [Developer Guide](../../docs/developer-guide.md) is for anyone wanting to either write code which directly accesses the kubernetes API, or to contribute directly to the kubernetes project.
Please ensure you have completed the [prerequisites for running examples from the user guide](prereqs.md).
## Quick walkthrough
1.[Kubernetes 101](walkthrough/README.md)
1.[Kubernetes 201](walkthrough/k8s201.md)
## Thorough walkthrough
If you don't have much familiarity with Kubernetes, we recommend you read the following sections in order:
1.[Quick start: launch and expose an application](quick-start.md)
1.[Configuring and launching containers: configuring common container parameters](configuring-containers.md)
1.[Connecting applications: exposing applications to clients and users](connecting-applications.md)
1.[Working with containers in production](production-pods.md)
1.[Managing deployments](managing-deployments.md)
1.[Application introspection and debugging](introspection-and-debugging.md)
1.[Using the Kubernetes web user interface](ui.md)
1.[Logging](logging.md)
1.[Monitoring](monitoring.md)
1.[Getting into containers via `exec`](getting-into-containers.md)
1.[Connecting to containers via proxies](connecting-to-applications-proxy.md)
1.[Connecting to containers via port forwarding](connecting-to-applications-port-forward.md)
## Concept guide
[**Overview**](overview.md)
: A brief overview of Kubernetes concepts.
[**Pod**](pods.md)
: A pod is a co-located group of containers and volumes.
[**Label**](labels.md)
: A label is a key/value pair that is attached to a resource, such as a pod, to convey a user-defined identifying attribute. Labels can be used to organize and to select subsets of resources.
[**Selector**](labels.md#label-selectors)
: A selector is an expression that matches labels in order to identify related resources, such as which pods are targeted by a load-balanced service.
: A replication controller ensures that a specified number of pod replicas are running at any one time. It both allows for easy scaling of replicated systems and handles re-creation of a pod when the machine it is on reboots or otherwise fails.
[**Service**](services.md)
: A service defines a set of pods and a means by which to access them, such as single stable IP address and corresponding DNS name.
[**Volume**](volumes.md)
: A volume is a directory, possibly with some data in it, which is accessible to a Container as part of its filesystem. Kubernetes volumes build upon [Docker Volumes](https://docs.docker.com/userguide/dockervolumes/), adding provisioning of the volume directory and/or device.
[**Secret**](secrets.md)
: A secret stores sensitive data, such as authentication tokens, which can be made available to containers upon request.
[**Name**](identifiers.md)
: A user- or client-provided name for a resource.
[**Namespace**](namespaces.md)
: A namespace is like a prefix to the name of a resource. Namespaces help different projects, teams, or customers to share a cluster, such as by preventing name collisions between unrelated teams.
[**Annotation**](annotations.md)
: A key/value pair that can hold larger (compared to a label), and possibly not human-readable, data, intended to store non-identifying auxiliary data, especially data manipulated by tools and system extensions. Efficient filtering by annotation values is not supported.
## Further reading
* API resources
*[Working with resources](working-with-resources.md)
* Pods and containers
*[Pod lifecycle and restart policies](pod-states.md)
*[Lifecycle hooks](container-environment.md)
*[Compute resources, such as cpu and memory](compute-resources.md)
*[Specifying commands and requesting capabilities](containers.md)
*[Downward API: accessing system configuration from a pod](downward-api.md)
@@ -20,11 +20,13 @@ certainly want the docs that go with that version.</h1>
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# Kubernetes User Documentation
# Kubernetes Overview
Kubernetes is an open-source system for managing containerized applications across multiple hosts in a cluster. It provides mechanisms for application deployment, scheduling, updating, maintenance, and scaling. A key feature of Kubernetes is that it actively manages the containers to ensure that the state of the cluster continually matches the user's intentions.
Today, Kubernetes supports just [Docker](http://www.docker.io) containers, but other container image formats and container runtimes will be supported in the future (e.g., [Rocket](https://coreos.com/blog/rocket/) support is in progress). Similarly, while Kubernetes currently focuses on continuously-running stateless (e.g. web server or in-memory object cache) and "cloud native" stateful applications (e.g. NoSQL datastores), in the near future it will support all the other workload types commonly found in production cluster environments, such as batch, stream processing, and traditional databases.
Kubernetes supports [Docker](http://www.docker.io) and [Rocket](https://coreos.com/blog/rocket/) containers, and other container image formats and container runtimes will be supported in the future.
While Kubernetes currently focuses on continuously-running stateless (e.g. web server or in-memory object cache) and "cloud native" stateful applications (e.g. NoSQL datastores), in the near future it will support all the other workload types commonly found in production cluster environments, such as batch, stream processing, and traditional databases.
In Kubernetes, all containers run inside [pods](pods.md). A pod can host a single container, or multiple cooperating containers; in the latter case, the containers in the pod are guaranteed to be co-located on the same machine and can share resources. A pod can also contain zero or more [volumes](volumes.md), which are directories that are private to a container or shared across containers in a pod. For each pod the user creates, the system finds a machine that is healthy and that has sufficient available capacity, and starts up the corresponding container(s) there. If a container fails it can be automatically restarted by Kubernetes' node agent, called the Kubelet. But if the pod or its machine fails, it is not automatically moved or restarted unless the user also defines a [replication controller](replication-controller.md), which we discuss next.
...
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@@ -38,17 +40,6 @@ Modern Internet applications are commonly built by layering micro-services, for
Every resource in Kubernetes, such as a pod, is identified by a URI and has a UID. Important components of the URI are the kind of object (e.g. pod), the object’s name, and the object’s [namespace](namespaces.md). For a certain object kind, every name is unique within its namespace. In contexts where an object name is provided without a namespace, it is assumed to be in the default namespace. UID is unique across time and space.
