64 lines
2.2 KiB
Markdown
64 lines
2.2 KiB
Markdown
# Service Account
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Service account是为了方便Pod里面的进程调用Kubernetes API或其他外部服务，它不同于User account：
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- User account是为人设计的，而service account则是为了Pod中的进程；
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- User account是跨namespace的，而service account则是仅局限它所在的namespace；
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- 开启ServiceAccount（默认开启）后，每个namespace都会自动创建一个Service account，并会相应的secret挂载到每一个Pod中
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- 默认ServiceAccount为default，自动关联一个访问kubernetes API的[Secret](Secret.md)
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- 每个Pod在创建后都会自动设置`spec.serviceAccount`为default（除非指定了其他ServiceAccout）
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- 每个container启动后都会挂载对应的token和`ca.crt`到`/var/run/secrets/kubernetes.io/serviceaccount/`
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当然了，也可以创建更多的Service Account：
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```
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$ cat > /tmp/serviceaccount.yaml <<EOF
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apiVersion: v1
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kind: ServiceAccount
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metadata:
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name: build-robot
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namespace: default
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EOF
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$ kubectl create -f /tmp/serviceaccount.yaml
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serviceaccounts/build-robot
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```
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Service Account为服务提供了一种方便的认知机制，但它不关心授权的问题。可以配合[RBAC](https://kubernetes.io/docs/admin/authorization/#a-quick-note-on-service-accounts)来为Service Account鉴权：
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- 配置`--authorization-mode=RBAC`和`--runtime-config=rbac.authorization.k8s.io/v1alpha1`
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- 配置`--authorization-rbac-super-user=admin`
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- 定义Role、ClusterRole、RoleBinding或ClusterRoleBinding
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比如
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```yaml
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# This role allows to read pods in the namespace "default"
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kind: Role
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apiVersion: rbac.authorization.k8s.io/v1alpha1
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metadata:
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namespace: default
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name: pod-reader
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rules:
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- apiGroups: [""] # The API group "" indicates the core API Group.
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resources: ["pods"]
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verbs: ["get", "watch", "list"]
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nonResourceURLs: []
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---
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# This role binding allows "default" to read pods in the namespace "default"
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kind: RoleBinding
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apiVersion: rbac.authorization.k8s.io/v1alpha1
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metadata:
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name: read-pods
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namespace: default
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subjects:
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- kind: ServiceAccount # May be "User", "Group" or "ServiceAccount"
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name: default
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roleRef:
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kind: Role
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name: pod-reader
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apiGroup: rbac.authorization.k8s.io
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```
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