kubernetes的Service Account和secret

系列目錄

Service Account

Service Account概念的引入是基於這樣的使用場景：運行在pod里的進程需要調用Kubernetes API以及非Kubernetes API的其它服務。Service Account它並不是給kubernetes集群的用戶使用的，而是給pod里面的進程使用的，它為pod提供必要的身份認證。

kubectl get sa --all-namespaces

NAMESPACE     NAME          SECRETS   AGE
default       build-robot   1         1d
default       default       1         32d
default       kube-dns      1         31d
kube-public   default       1         32d
kube-system   dashboard     1         31d
kube-system   default       1         32d
kube-system   heapster      1         30d
kube-system   kube-dns      1         31d

如果kubernetes開啟了ServiceAccount（–admission_control=…,ServiceAccount,… ）那么會在每個namespace下面都會創建一個默認的default的sa。
如下，其中最重要的就是secrets，它是每個sa下面都會擁有的一個加密的token，這個在下面的secret會詳細介紹。

kubectl get sa  default  -o yaml

apiVersion: v1
kind: ServiceAccount
metadata:
  creationTimestamp: 2017-05-02T06:39:12Z
  name: default
  namespace: default
  resourceVersion: "175"
  selfLink: /api/v1/namespaces/default/serviceaccounts/default
  uid: 0de23575-2f02-11e7-98d0-5254c4628ad9
secrets:
- name: default-token-rsf8r

當用戶在該namespace下創建pod的時候都會默認使用這個sa，下面是get pod 截取的部分，可以看到kubernetes會把默認的sa掛載到容器內。

  volumes:
  - name: default-token-rsf8r
    secret:
      defaultMode: 420
      secretName: default-token-rsf8r

具體看一下secret

kubectl get secret default-token-rsf8r -o yaml
apiVersion: v1
data:
  ca.crt: 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
  namespace: ZGVmYXVsdA==
  token: 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
kind: Secret
metadata:
  annotations:
    kubernetes.io/service-account.name: default
    kubernetes.io/service-account.uid: 0de23575-2f02-11e7-98d0-5254c4628ad9
  creationTimestamp: 2017-05-02T06:42:07Z
  name: default-token-rsf8r
  namespace: default
  resourceVersion: "12551"
  selfLink: /api/v1/namespaces/default/secrets/default-token-rsf8r
  uid: 75c0a236-2f02-11e7-98d0-5254c4628ad9
type: kubernetes.io/service-account-token

上面的內容是經過base64加密過后的，我們直接進入容器內：

~  ls -l  /var/run/secrets/kubernetes.io/serviceaccount/
total 0
lrwxrwxrwx    1 root     root            13 May  4 23:57 ca.crt -> ..data/ca.crt
lrwxrwxrwx    1 root     root            16 May  4 23:57 namespace -> ..data/namespace
lrwxrwxrwx    1 root     root            12 May  4 23:57 token -> ..data/token

可以看到已將ca.crt 、namespace和token放到容器內了，那么這個容器就可以通過https的請求訪問apiserver了。

Secret

Kubernetes提供了Secret來處理敏感信息，目前Secret的類型有3種:

• Opaque(default): 任意字符串
• kubernetes.io/service-account-token: 作用於ServiceAccount，就是上面說的。
• kubernetes.io/dockercfg: 作用於Docker registry，用戶下載docker鏡像認證使用。

Opaque Secret

Opaque Secret就是字符串

apiVersion: v1
kind: Secret
metadata:
  name: mysecret
type: Opaque
data:
  username: YWRtaW4=
  password: MWYyZDFlMmU2N2Rm

在使用的時候可以選擇已volume方式或者是已環境變量的方式放到容器內使用。

{
 "apiVersion": "v1",
 "kind": "Pod",
  "metadata": {
    "name": "mypod",
    "namespace": "default"
  },
  "spec": {
    "containers": [{
      "name": "mypod",
      "image": "busybox",
      "command": ["sleep","3600"],
      "imagePullPolicy": "IfNotPresent",
      "volumeMounts": [{
        "name": "foo",
        "mountPath": "/etc/foo",
        "readOnly": true
      }]
    }],
    "volumes": [{
      "name": "foo",
      "secret": {
        "secretName": "mysecret"
      }
    }]
  }
}

這樣就可以通過文件的方式掛載到容器內，在/etc/foo目錄下會生成這個文件。
如果是環境變量當然也是ok的

apiVersion: v1
kind: Pod
metadata:
  name: secret-env-pod
spec:
  containers:
    - name: mycontainer
      image: busybox
      imagePullPolicy: IfNotPresent
      command:
        - sleep
        - "3600"
      env:
        - name: SECRET_USERNAME
          valueFrom:
            secretKeyRef:
              name: mysecret
              key: username
        - name: SECRET_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysecret
              key: password

進入容器通過env命令，你將可以看到這兩個環境變量被注入到容器內

imagePullSecrets

當在需要安全驗證的環境中拉取鏡像的時候，需要通過用戶名和密碼。

apiVersion: v1
kind: Secret
metadata:
  name: myregistrykey
  namespace: awesomeapps
data:
  .dockerconfigjson: UmVhbGx5IHJlYWxseSByZWVlZWVlZWVlZWFhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGx5eXl5eXl5eXl5eXl5eXl5eXl5eSBsbGxsbGxsbGxsbGxsbG9vb29vb29vb29vb29vb29vb29vb29vb29vb25ubm5ubm5ubm5ubm5ubm5ubm5ubm5ubmdnZ2dnZ2dnZ2dnZ2dnZ2dnZ2cgYXV0aCBrZXlzCg==
type: kubernetes.io/dockerconfigjson

或者直接通過命令創建

kubectl create secret docker-registry myregistrykey --docker-server=DOCKER_REGISTRY_SERVER --docker-username=DOCKER_USER --docker-password=DOCKER_PASSWORD --docker-email=DOCKER_EMAIL