Kubernetes集群之YAML文件详解

Kubernetes只支持YAML和JSON格式创建资源对象。JSON格式一般用于接口之间消息的传递，YAML是专门用来写配置文件的语言，非常简洁和强大，可读性高。它实质上是一种通用的数据串行化格式。

一、YAML语法规则

• 缩进标识层级关系

• 不支持制表符缩进，使用空格缩进

• 通常开头缩进两个空格

• 字符后缩进一个空格，如冒号，逗号等

• "---"表示YAML格式，一个文件的开始

• "#"表示注释

二、K8s中YAML字段类型

• 常用字段

apiVersion	API版本
kind	资源类型
metadata	资源元数据
spec	资源规格
replicas	副本数量
selector	标签选择器
template	pod模板
metadata	pod原数据
spec	pod规格
containers	容器配置
resources	资源管理

• apiVersion

      1. apiVersion支持类型

# kubectl api-versions
admissionregistration.k8s.io/v1
admissionregistration.k8s.io/v1beta1
apiextensions.k8s.io/v1
apiextensions.k8s.io/v1beta1
apiregistration.k8s.io/v1
apiregistration.k8s.io/v1beta1
apps/v1
......

     2. apiVersion 选型

        从上得知apiVersion类型如此之多，那到底我们应该选那个，可以根据对应的资源类型来选择

# 可以参考到某个kind资源拥有的字段以及对应的apiVersion

# kubectl explain {kind_name}
# kubectl explain deployment
KIND:     Deployment
VERSION:  apps/v1

DESCRIPTION:
     Deployment enables declarative updates for Pods and ReplicaSets.
......

• kind

      1. 资源类型

# kubectl api-resources -o wide --namespaced=true
NAME                        SHORTNAMES   APIGROUP                    NAMESPACED   KIND                       VERBS
bindings                                                             true         Binding                    [create]
configmaps                  cm                                       true         ConfigMap                  [create delete deletecollection get list patch update watch]
endpoints                   ep                                       true         Endpoints                  [create delete deletecollection get list patch update watch]
events                      ev                                       true         Event                      [create delete deletecollection get list patch update watch]
limitranges                 limits                                   true         LimitRange                 [create delete deletecollection get list patch update watch]
persistentvolumeclaims      pvc                                      true         PersistentVolumeClaim      [create delete deletecollection get list patch update watch]
pods                        po                                       true         Pod                        [create delete deletecollection get list patch update watch]
.......

    2. 资源类型支持字段

# kubectl explain ingresses  --recursive
KIND:     Ingress
VERSION:  extensions/v1beta1

DESCRIPTION:
     Ingress is a collection of rules that allow inbound connections to reach
     the endpoints defined by a backend. An Ingress can be configured to give
     services externally-reachable urls, load balance traffic, terminate SSL,
     offer name based virtual hosting etc. DEPRECATED - This group version of
     Ingress is deprecated by networking.k8s.io/v1beta1 Ingress. See the release
     notes for more information.

FIELDS:
   apiVersion	
   kind	
   metadata