12-Overview-Recommended Labels

cucytoman發表於2019-09-24
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concepts/overview/working-with-objects/common-labels/

您可以使用比kubectl和儀表板更多的工具來視覺化和管理kubernetes物件。一組通用的標籤允許工具互操作，以所有工具都能理解的通用方式描述物件。
除了支援工具之外，推薦的標籤還以可查詢的方式描述應用程式。

後設資料是圍繞應用程式的概念組織的。kubernetes不是一個平臺即服務（platform as-as-a-service，paas），也沒有或沒有強制執行應用程式的正式概念。相反，應用程式是非正式的，用後設資料來描述。應用程式所包含內容的定義是鬆散的。

Note: These are recommended labels. They make it easier to manage applications but aren’t required for any core tooling.

共享標籤和批註共享一個公共字首：“app.kubernetes.io”。沒有字首的標籤是使用者專用的。共享字首確保共享標籤不會干擾自定義使用者標籤。

Labels

為了充分利用這些標籤，應該在每個資源物件上應用它們。

Key Description Example Type
app.kubernetes.io/name The name of the application mysql string
app.kubernetes.io/instance A unique name identifying the instance of an application wordpress-abcxzy string
app.kubernetes.io/version The current version of the application (e.g., a semantic version, revision hash, etc.) 5.7.21 string
app.kubernetes.io/component The component within the architecture database string
app.kubernetes.io/part-of The name of a higher level application this one is part of wordpress string
app.kubernetes.io/managed-by The tool being used to manage the operation of an application helm string

To illustrate these labels in action, consider the following StatefulSet object:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  labels:
    app.kubernetes.io/name: mysql
    app.kubernetes.io/instance: wordpress-abcxzy
    app.kubernetes.io/version: "5.7.21"
    app.kubernetes.io/component: database
    app.kubernetes.io/part-of: wordpress
    app.kubernetes.io/managed-by: helm

Applications And Instances Of Applications

An application can be installed one or more times into a Kubernetes cluster and, in some cases, the same namespace. For example, wordpress can be installed more than once where different websites are different installations of wordpress.應用程式可以安裝到kubernetes叢集中一次或多次，在某些情況下，也可以安裝到同一名稱空間中。例如，WordPress可以在不同網站安裝WordPress時多次安裝。

The name of an application and the instance name are recorded separately. For example, WordPress has a app.kubernetes.io/name of wordpress while it has an instance name, represented as app.kubernetes.io/instance with a value of wordpress-abcxzy. This enables the application and instance of the application to be identifiable. Every instance of an application must have a unique name.應用程式名和例項名分別記錄。例如，wordpress的“app.kubernetes.io/name”為“wordpress”，而例項名為“app.kubernetes.io/instance”，值為“wordpress abcxzy”。這使得應用程式和應用程式例項可以識別。應用程式的每個例項都必須具有唯一的名稱。

Examples

To illustrate different ways to use these labels the following examples have varying complexity.為了說明使用這些標籤的不同方法，下面的示例具有不同的複雜性。

A Simple Stateless Service

考慮使用 Deployment and Service objects. 下面的兩個片段代表瞭如何以最簡單的形式使用標籤。

The Deployment 用於監視執行應用程式本身的pod.

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app.kubernetes.io/name: myservice
    app.kubernetes.io/instance: myservice-abcxzy
...

The Service is used to expose the application.

apiVersion: v1
kind: Service
metadata:
  labels:
    app.kubernetes.io/name: myservice
    app.kubernetes.io/instance: myservice-abcxzy
...

Web Application With A Database

考慮一個稍微複雜一點的應用程式：使用資料庫（mysql）的web應用程式（wordpress），使用helm安裝。下面的程式碼片段演示了用於部署此應用程式的物件的開始。

The start to the following Deployment is used for WordPress:

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app.kubernetes.io/name: wordpress
    app.kubernetes.io/instance: wordpress-abcxzy
    app.kubernetes.io/version: "4.9.4"
    app.kubernetes.io/managed-by: helm
    app.kubernetes.io/component: server
    app.kubernetes.io/part-of: wordpress
...

The Service is used to expose WordPress:

apiVersion: v1
kind: Service
metadata:
  labels:
    app.kubernetes.io/name: wordpress
    app.kubernetes.io/instance: wordpress-abcxzy
    app.kubernetes.io/version: "4.9.4"
    app.kubernetes.io/managed-by: helm
    app.kubernetes.io/component: server
    app.kubernetes.io/part-of: wordpress
...

MySQL is exposed as a StatefulSet以及它所屬的更大的應用程式的後設資料:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  labels:
    app.kubernetes.io/name: mysql
    app.kubernetes.io/instance: mysql-abcxzy
    app.kubernetes.io/version: "5.7.21"
    app.kubernetes.io/managed-by: helm
    app.kubernetes.io/component: database
    app.kubernetes.io/part-of: wordpress
...

The Service is used to expose MySQL as part of WordPress:

apiVersion: v1
kind: Service
metadata:
  labels:
    app.kubernetes.io/name: mysql
    app.kubernetes.io/instance: mysql-abcxzy
    app.kubernetes.io/version: "5.7.21"
    app.kubernetes.io/managed-by: helm
    app.kubernetes.io/component: database
    app.kubernetes.io/part-of: wordpress
...

With the MySQL StatefulSet and Service you’ll notice information about both MySQL and Wordpress, the broader application, are included.使用mysql的statefulset和service，您會注意到mysql和wordpress這兩個更廣泛的應用程式的相關資訊。

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