yaml文件

YAML 是专门用来编写配置文件的语言，实质上是一种通用的数据串行化格式。

语法规则：

• 大小写敏感
• 使用缩进表示层级关系
• 缩进时不允许使用Tab键，只允许使用空格
• 缩进的空格数目不重要，只要相同层级的元素左侧对齐即可

• 表示注释，从这个字符一直到行尾，都会被解析器忽略

在 Kubernetes 中，基本只用到【字典/列表】两种结构类型。

# Map 字典，是 key:value 的键值对
---
apiVersion: v1
kind: Pod
metadata:
  name: c-site
  labels:
    app: web
# 转换成 JSON 文件
{
    "apiVersion": "v1",
    "kind": "Pod",
    "metadata": {
        "name": "c-site",
        "labels": {
            "app": "web"
        }
    }
}
# Lists 列表，可以有任意数量的项在列表中，每个项的定义以破折号（-）开头的，与父元素之间可以缩进也可以不缩进。
args
  - Cat
  - Dog
  - Fish
# 对应的 JSON 格式
{
    "args": [ 'Cat', 'Dog', 'Fish' ]
}

Lists 的子项也可以是 Maps，Maps 的子项也可以是 Lists 。

#定义一个叫 containers 的 List 对象，每个子项都由 name、image、ports 组成，每个 ports 都有一个 key 为 containerPort 的 Map 组成

---
apiVersion: v1
kind: Pod
metadata:
  name: ydzs-site
  labels:
    app: web
spec:
  containers:
    - name: front-end
      image: nginx
      ports:
        - containerPort: 80
    - name: flaskapp-demo
      image: cnych/flaskapp
      ports:
        - containerPort: 5000

#转成 JSON 格式文件

{
    "apiVersion": "v1",
    "kind": "Pod",
    "metadata": {
        "name": "ydzs-site",
        "labels": {
            "app": "web"
        }
    },
    "spec": {
        "containers": [{
            "name": "front-end",
            "image": "nginx",
            "ports": [{
                "containerPort": "80"
            }]
        }, {
            "name": "flaskapp-demo",
            "image": "cnych/flaskapp",
            "ports": [{
                "containerPort": "5000"
            }]
        }]
    }
}

编写yaml

编写符合 Kubernetes API 对象的资源清单要清楚资源对象的功能和字段。可通过 kubectl 命令行工具来获取字段信息。

# kubectl explain deployment
KIND:     Deployment
VERSION:  apps/v1

DESCRIPTION:
     Deployment enables declarative updates for Pods and ReplicaSets.

FIELDS:
   apiVersion    <string>
     APIVersion defines the versioned schema of this representation of an
     object. Servers should convert recognized schemas to the latest internal
     value, and may reject unrecognized values. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources

   kind    <string>
     Kind is a string value representing the REST resource this object
     represents. Servers may infer this from the endpoint the client submits
     requests to. Cannot be updated. In CamelCase. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds

   metadata    <Object>
     Standard object metadata.

   spec    <Object>
     Specification of the desired behavior of the Deployment.

   status    <Object>
     Most recently observed status of the Deployment.

spec