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kuernetes yamlファイルの書き方


LinuCエヴァンジェリストの鯨井貴博@opensourcetechです。


はじめに


今回は、kubernetesを使う際に必要となるyamlファイルの書き方に関するメモです。
何となくこんな感じで書けばいいんだろうと、他の方が使っているファイルを真似ていますが、
「ルールってあるの?」と思ったので調べてみました。


yamlの例


公式サイトを見ると、
以下の例が載っています。

apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 2 # tells deployment to run 2 pods matching the template
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

https://kubernetes.io/ja/docs/concepts/overview/working-with-objects/kubernetes-objects/
書かれている内容はシンプルで、
nginxバージョン1.14.2のコンテナイメージを使って、2つ(replicas)のコンテナを起動するというもの。
そして、それを"nginx-deployment"というDeployment名としています。



yamlの記載ルール


yamlの記載ルールですが、以下の3点。
・インデントは、スペース2つ
・"name:"の:(コロン)のあとは、スペースを1つ

metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx


・複数の情報を一つのyamlファイル内に書く場合、
 "--"で区切る。

.
.
.
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: calico-kube-controllers
  namespace: kube-system
---
apiVersion: policy/v1beta1
kind: PodDisruptionBudget
.
.
.




既にあるdeploymentなどからyamlを作成する


以下のDeploymentがあるとします。

kubeuser@kubemaster1:~$ kubectl get deployments,pods
NAME                    READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx   2/2     2            2           23h

NAME                         READY   STATUS    RESTARTS   AGE
pod/nginx-6c67f5ff6f-cc6x8   1/1     Running   0          23h
pod/nginx-6c67f5ff6f-rkwt2   1/1     Running   0          23h


この場合、kubectl getに""-o xxx.yamlオプションを付けることで、
yaml形式で出力させることが可能です。

kubeuser@kubemaster1:~$ kubectl get deployments nginx -o yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "1"
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{"deployment.kubernetes.io/revision":"1"},"generation":1,"labels":{"app":"nginx"},"managedFields":[{"apiVersion":"apps/v1","fieldsType":"FieldsV1","fieldsV1":{"f:metadata":{"f:labels":{".":{},"f:app":{}}},"f:spec":{"f:progressDeadlineSeconds":{},"f:replicas":{},"f:revisionHistoryLimit":{},"f:selector":{"f:matchLabels":{".":{},"f:app":{}}},"f:strategy":{"f:rollingUpdate":{".":{},"f:maxSurge":{},"f:maxUnavailable":{}},"f:type":{}},"f:template":{"f:metadata":{"f:labels":{".":{},"f:app":{}}},"f:spec":{"f:containers":{"k:{\"name\":\"nginx\"}":{".":{},"f:image":{},"f:imagePullPolicy":{},"f:name":{},"f:resources":{},"f:terminationMessagePath":{},"f:terminationMessagePolicy":{}}},"f:dnsPolicy":{},"f:restartPolicy":{},"f:schedulerName":{},"f:securityContext":{},"f:terminationGracePeriodSeconds":{}}}}},"manager":"kubectl","operation":"Update","time":"2021-12-01T13:41:24Z"},{"apiVersion":"apps/v1","fieldsType":"FieldsV1","fieldsV1":{"f:metadata":{"f:annotations":{".":{},"f:deployment.kubernetes.io/revision":{}}},"f:status":{"f:availableReplicas":{},"f:conditions":{".":{},"k:{\"type\":\"Available\"}":{".":{},"f:lastTransitionTime":{},"f:lastUpdateTime":{},"f:message":{},"f:reason":{},"f:status":{},"f:type":{}},"k:{\"type\":\"Progressing\"}":{".":{},"f:lastTransitionTime":{},"f:lastUpdateTime":{},"f:message":{},"f:reason":{},"f:status":{},"f:type":{}}},"f:observedGeneration":{},"f:readyReplicas":{},"f:replicas":{},"f:updatedReplicas":{}}},"manager":"kube-controller-manager","operation":"Update","time":"2021-12-01T13:42:09Z"}],"name":"nginx","namespace":"default"},"spec":{"progressDeadlineSeconds":600,"replicas":2,"revisionHistoryLimit":10,"selector":{"matchLabels":{"app":"nginx"}},"strategy":{"rollingUpdate":{"maxSurge":"25%","maxUnavailable":"25%"},"type":"RollingUpdate"},"template":{"metadata":{"creationTimestamp":null,"labels":{"app":"nginx"}},"spec":{"containers":[{"image":"nginx:1.21.4","imagePullPolicy":"IfNotPresent","name":"nginx","resources":{},"terminationMessagePath":"/dev/termination-log","terminationMessagePolicy":"File"}],"dnsPolicy":"ClusterFirst","restartPolicy":"Always","schedulerName":"default-scheduler","securityContext":{},"terminationGracePeriodSeconds":30}}}}
  creationTimestamp: "2021-12-07T13:16:14Z"
  generation: 1
  labels:
    app: nginx
  managedFields:
  - apiVersion: apps/v1
    fieldsType: FieldsV1
    fieldsV1:
      f:metadata:
        f:labels:
          .: {}
          f:app: {}
      f:spec:
        f:progressDeadlineSeconds: {}
        f:replicas: {}
        f:revisionHistoryLimit: {}
        f:selector:
          f:matchLabels:
            .: {}
            f:app: {}
        f:strategy:
          f:rollingUpdate:
            .: {}
            f:maxSurge: {}
            f:maxUnavailable: {}
          f:type: {}
        f:template:
          f:metadata:
            f:labels:
              .: {}
              f:app: {}
          f:spec:
            f:containers:
              k:{"name":"nginx"}:
                .: {}
                f:image: {}
                f:imagePullPolicy: {}
                f:name: {}
                f:resources: {}
                f:terminationMessagePath: {}
                f:terminationMessagePolicy: {}
            f:dnsPolicy: {}
            f:restartPolicy: {}
            f:schedulerName: {}
            f:securityContext: {}
            f:terminationGracePeriodSeconds: {}
    manager: kubectl
    operation: Update
    time: "2021-12-01T13:41:24Z"
  - apiVersion: apps/v1
    fieldsType: FieldsV1
    fieldsV1:
      f:metadata:
        f:annotations:
          .: {}
          f:deployment.kubernetes.io/revision: {}
      f:status:
        f:availableReplicas: {}
        f:conditions:
          .: {}
          k:{"type":"Available"}:
            .: {}
            f:lastTransitionTime: {}
            f:lastUpdateTime: {}
            f:message: {}
            f:reason: {}
            f:status: {}
            f:type: {}
          k:{"type":"Progressing"}:
            .: {}
            f:lastTransitionTime: {}
            f:lastUpdateTime: {}
            f:message: {}
            f:reason: {}
            f:status: {}
            f:type: {}
        f:observedGeneration: {}
        f:readyReplicas: {}
        f:replicas: {}
        f:updatedReplicas: {}
    manager: kube-controller-manager
    operation: Update
    time: "2021-12-01T13:42:09Z"
  name: nginx
  namespace: default
  resourceVersion: "1442771"
  selfLink: /apis/apps/v1/namespaces/default/deployments/nginx
  uid: 2bb8b598-b3f9-4c36-a265-779c9123c2f5
spec:
  progressDeadlineSeconds: 600
  replicas: 2
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: nginx
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx:1.21.4
        imagePullPolicy: IfNotPresent
        name: nginx
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
status:
  availableReplicas: 2
  conditions:
  - lastTransitionTime: "2021-12-07T13:16:38Z"
    lastUpdateTime: "2021-12-07T13:16:38Z"
    message: Deployment has minimum availability.
    reason: MinimumReplicasAvailable
    status: "True"
    type: Available
  - lastTransitionTime: "2021-12-07T13:16:15Z"
    lastUpdateTime: "2021-12-07T13:16:38Z"
    message: ReplicaSet "nginx-6c67f5ff6f" has successfully progressed.
    reason: NewReplicaSetAvailable
    status: "True"
    type: Progressing
  observedGeneration: 1
  readyReplicas: 2
  replicas: 2
  updatedReplicas: 2


なので、これをリダイレクトしてファイルに保存して使う方法があります。

kubeuser@kubemaster1:~$ kubectl get deployments nginx -o yaml > nginx.yaml




参考:JSON形式で出力する


ちなみに、"-o json"とすることでJSON形式での出力も可能です。

kubeuser@kubemaster1:~$ kubectl get deployments nginx -o json
{
    "apiVersion": "apps/v1",
    "kind": "Deployment",
    "metadata": {
        "annotations": {
            "deployment.kubernetes.io/revision": "1",
            "kubectl.kubernetes.io/last-applied-configuration": "{\"apiVersion\":\"apps/v1\",\"kind\":\"Deployment\",\"metadata\":{\"annotations\":{\"deployment.kubernetes.io/revision\":\"1\"},\"generation\":1,\"labels\":{\"app\":\"nginx\"},\"managedFields\":[{\"apiVersion\":\"apps/v1\",\"fieldsType\":\"FieldsV1\",\"fieldsV1\":{\"f:metadata\":{\"f:labels\":{\".\":{},\"f:app\":{}}},\"f:spec\":{\"f:progressDeadlineSeconds\":{},\"f:replicas\":{},\"f:revisionHistoryLimit\":{},\"f:selector\":{\"f:matchLabels\":{\".\":{},\"f:app\":{}}},\"f:strategy\":{\"f:rollingUpdate\":{\".\":{},\"f:maxSurge\":{},\"f:maxUnavailable\":{}},\"f:type\":{}},\"f:template\":{\"f:metadata\":{\"f:labels\":{\".\":{},\"f:app\":{}}},\"f:spec\":{\"f:containers\":{\"k:{\\\"name\\\":\\\"nginx\\\"}\":{\".\":{},\"f:image\":{},\"f:imagePullPolicy\":{},\"f:name\":{},\"f:resources\":{},\"f:terminationMessagePath\":{},\"f:terminationMessagePolicy\":{}}},\"f:dnsPolicy\":{},\"f:restartPolicy\":{},\"f:schedulerName\":{},\"f:securityContext\":{},\"f:terminationGracePeriodSeconds\":{}}}}},\"manager\":\"kubectl\",\"operation\":\"Update\",\"time\":\"2021-12-01T13:41:24Z\"},{\"apiVersion\":\"apps/v1\",\"fieldsType\":\"FieldsV1\",\"fieldsV1\":{\"f:metadata\":{\"f:annotations\":{\".\":{},\"f:deployment.kubernetes.io/revision\":{}}},\"f:status\":{\"f:availableReplicas\":{},\"f:conditions\":{\".\":{},\"k:{\\\"type\\\":\\\"Available\\\"}\":{\".\":{},\"f:lastTransitionTime\":{},\"f:lastUpdateTime\":{},\"f:message\":{},\"f:reason\":{},\"f:status\":{},\"f:type\":{}},\"k:{\\\"type\\\":\\\"Progressing\\\"}\":{\".\":{},\"f:lastTransitionTime\":{},\"f:lastUpdateTime\":{},\"f:message\":{},\"f:reason\":{},\"f:status\":{},\"f:type\":{}}},\"f:observedGeneration\":{},\"f:readyReplicas\":{},\"f:replicas\":{},\"f:updatedReplicas\":{}}},\"manager\":\"kube-controller-manager\",\"operation\":\"Update\",\"time\":\"2021-12-01T13:42:09Z\"}],\"name\":\"nginx\",\"namespace\":\"default\"},\"spec\":{\"progressDeadlineSeconds\":600,\"replicas\":2,\"revisionHistoryLimit\":10,\"selector\":{\"matchLabels\":{\"app\":\"nginx\"}},\"strategy\":{\"rollingUpdate\":{\"maxSurge\":\"25%\",\"maxUnavailable\":\"25%\"},\"type\":\"RollingUpdate\"},\"template\":{\"metadata\":{\"creationTimestamp\":null,\"labels\":{\"app\":\"nginx\"}},\"spec\":{\"containers\":[{\"image\":\"nginx:1.21.4\",\"imagePullPolicy\":\"IfNotPresent\",\"name\":\"nginx\",\"resources\":{},\"terminationMessagePath\":\"/dev/termination-log\",\"terminationMessagePolicy\":\"File\"}],\"dnsPolicy\":\"ClusterFirst\",\"restartPolicy\":\"Always\",\"schedulerName\":\"default-scheduler\",\"securityContext\":{},\"terminationGracePeriodSeconds\":30}}}}\n"
        },
        "creationTimestamp": "2021-12-07T13:16:14Z",
        "generation": 1,
        "labels": {
            "app": "nginx"
        },
        "managedFields": [
            {
                "apiVersion": "apps/v1",
                "fieldsType": "FieldsV1",
                "fieldsV1": {
                    "f:metadata": {
                        "f:labels": {
                            ".": {},
                            "f:app": {}
                        }
                    },
                    "f:spec": {
                        "f:progressDeadlineSeconds": {},
                        "f:replicas": {},
                        "f:revisionHistoryLimit": {},
                        "f:selector": {
                            "f:matchLabels": {
                                ".": {},
                                "f:app": {}
                            }
                        },
                        "f:strategy": {
                            "f:rollingUpdate": {
                                ".": {},
                                "f:maxSurge": {},
                                "f:maxUnavailable": {}
                            },
                            "f:type": {}
                        },
                        "f:template": {
                            "f:metadata": {
                                "f:labels": {
                                    ".": {},
                                    "f:app": {}
                                }
                            },
                            "f:spec": {
                                "f:containers": {
                                    "k:{\"name\":\"nginx\"}": {
                                        ".": {},
                                        "f:image": {},
                                        "f:imagePullPolicy": {},
                                        "f:name": {},
                                        "f:resources": {},
                                        "f:terminationMessagePath": {},
                                        "f:terminationMessagePolicy": {}
                                    }
                                },
                                "f:dnsPolicy": {},
                                "f:restartPolicy": {},
                                "f:schedulerName": {},
                                "f:securityContext": {},
                                "f:terminationGracePeriodSeconds": {}
                            }
                        }
                    }
                },
                "manager": "kubectl",
                "operation": "Update",
                "time": "2021-12-01T13:41:24Z"
            },
            {
                "apiVersion": "apps/v1",
                "fieldsType": "FieldsV1",
                "fieldsV1": {
                    "f:metadata": {
                        "f:annotations": {
                            ".": {},
                            "f:deployment.kubernetes.io/revision": {}
                        }
                    },
                    "f:status": {
                        "f:availableReplicas": {},
                        "f:conditions": {
                            ".": {},
                            "k:{\"type\":\"Available\"}": {
                                ".": {},
                                "f:lastTransitionTime": {},
                                "f:lastUpdateTime": {},
                                "f:message": {},
                                "f:reason": {},
                                "f:status": {},
                                "f:type": {}
                            },
                            "k:{\"type\":\"Progressing\"}": {
                                ".": {},
                                "f:lastTransitionTime": {},
                                "f:lastUpdateTime": {},
                                "f:message": {},
                                "f:reason": {},
                                "f:status": {},
                                "f:type": {}
                            }
                        },
                        "f:observedGeneration": {},
                        "f:readyReplicas": {},
                        "f:replicas": {},
                        "f:updatedReplicas": {}
                    }
                },
                "manager": "kube-controller-manager",
                "operation": "Update",
                "time": "2021-12-01T13:42:09Z"
            }
        ],
        "name": "nginx",
        "namespace": "default",
        "resourceVersion": "1442771",
        "selfLink": "/apis/apps/v1/namespaces/default/deployments/nginx",
        "uid": "2bb8b598-b3f9-4c36-a265-779c9123c2f5"
    },
    "spec": {
        "progressDeadlineSeconds": 600,
        "replicas": 2,
        "revisionHistoryLimit": 10,
        "selector": {
            "matchLabels": {
                "app": "nginx"
            }
        },
        "strategy": {
            "rollingUpdate": {
                "maxSurge": "25%",
                "maxUnavailable": "25%"
            },
            "type": "RollingUpdate"
        },
        "template": {
            "metadata": {
                "creationTimestamp": null,
                "labels": {
                    "app": "nginx"
                }
            },
            "spec": {
                "containers": [
                    {
                        "image": "nginx:1.21.4",
                        "imagePullPolicy": "IfNotPresent",
                        "name": "nginx",
                        "resources": {},
                        "terminationMessagePath": "/dev/termination-log",
                        "terminationMessagePolicy": "File"
                    }
                ],
                "dnsPolicy": "ClusterFirst",
                "restartPolicy": "Always",
                "schedulerName": "default-scheduler",
                "securityContext": {},
                "terminationGracePeriodSeconds": 30
            }
        }
    },
    "status": {
        "availableReplicas": 2,
        "conditions": [
            {
                "lastTransitionTime": "2021-12-07T13:16:38Z",
                "lastUpdateTime": "2021-12-07T13:16:38Z",
                "message": "Deployment has minimum availability.",
                "reason": "MinimumReplicasAvailable",
                "status": "True",
                "type": "Available"
            },
            {
                "lastTransitionTime": "2021-12-07T13:16:15Z",
                "lastUpdateTime": "2021-12-07T13:16:38Z",
                "message": "ReplicaSet \"nginx-6c67f5ff6f\" has successfully progressed.",
                "reason": "NewReplicaSetAvailable",
                "status": "True",
                "type": "Progressing"
            }
        ],
        "observedGeneration": 1,
        "readyReplicas": 2,
        "replicas": 2,
        "updatedReplicas": 2
    }
}




おわりに


何もない状態から手書きするの大変だなと思っていたので、
yaml形式で出力する方法は便利ですね!

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