学习 Kubernetes 第三天 - Kubernetes API 学习

学习总结：这一节主要介绍了 Kubernetes API 的一些常见概念，以及这些概念之间的关系， 比如 group, resources，collections。接着简单介绍了 watch 功能，叙述了 Kubernetes 怎样处理大块的数据返回（其实就是分页）。总体来说比较简单。

Kubernetes API Overview

The REST API is the fundamental fabric of Kubernetes.

  1. API versioning
  2. API groups
    • core(legacy) group: /api/v1
    • named groups: /apis/$GROUP_NAME/$VERSION=
  3. Enabling API groups
  4. Enabling resources in the groups

简单讲了 Kubernetes API 的一些规则和能力

  • API 有版本
  • 可以分 group，方便扩展（提示：Group 是有版本的）
  • group 可以 enable 和 disable
  • group 中的 resources 也可以 enable 和 disable
  • 需要注意 group 和 resources 的区别

Kubernetes API Conceptd

Standard API terminology

Kubernetes generally leverages standard RESTful terminology to describe the API concepts:

  • A resource type is the name used in the URL (pods, namespaces, services)
  • All resource types have a concrete representation in JSON (their object schema) which is called a kind
  • A list of instances of a resource type is known as a collection
  • A single instance of the resource type is called a resource

Kubernetes API 常见的一些术语，以及它们的概念

  • a namespace is a cluster-scoped resource type
  • All resource types are either scoped by the cluster (/apis/GROUP/VERSION/*) or to a namespace (/apis/GROUP/VERSION/namespaces/NAMESPACE/*).
  • Some resource types will have one or more sub-resources

这些概念之间的一些关系

Efficient detection of changes

To enable clients to build a model of the current state of a cluster, all Kubernetes object resource types are required to support consistent lists and an incremental change notification feed called a watch.

Every Kubernetes object has a resourceVersion.

传一个 resourceVersion 给 apiserver，apiserver 会返回这个版本之后的所有变化信息。 A given Kubernetes server will only preserve a historical list of changes for a limited time.

Retrieving large results sets in chunks

To retrieve a single list in chunks, two new parameters limit and continue are supported on collection requests and a new field continue is returned from all list operations in the list metadata field.

continue 是一个 token，它有可能会失效，默认 5 分钟失效。

Receiving resources as Tables

apiserver 支持按照 table 形式输出数据，返回结果中会有 Column Title 等东西。

Alternate representations of resources

默认使用 JSON，支持 protobuf。

Client Libraries

忽略

Kubernetes Deprecation Policy

忽略

Accessing the API

介绍很多 API 认证方式，先忽略

CLI 以及 API Reference

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