58 lines
2.0 KiB
Markdown
58 lines
2.0 KiB
Markdown
# ReplicationController 和 ReplicaSet
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ReplicationController 用来确保容器应用的副本数始终保持在用户定义的副本数，即如果有容器异常退出，会自动创建新的 Pod 来替代；而如果异常多出来的容器也会自动回收。
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在新版本的 Kubernetes 中建议使用 ReplicaSet 来取代 ReplicationController。ReplicaSet 跟 ReplicationController 没有本质的不同，只是名字不一样，并且 ReplicaSet 支持集合式的 selector。
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虽然 ReplicaSet 可以独立使用，但一般还是建议使用 Deployment 来自动管理 ReplicaSet，这样就无需担心跟其他机制的不兼容问题（比如 ReplicaSet 不支持 rolling-update 但 Deployment 支持）。
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ReplicaSet 示例：
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```yaml
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apiVersion: extensions/v1beta1
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kind: ReplicaSet
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metadata:
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name: frontend
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# these labels can be applied automatically
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# from the labels in the pod template if not set
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# labels:
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# app: guestbook
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# tier: frontend
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spec:
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# this replicas value is default
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# modify it according to your case
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replicas: 3
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# selector can be applied automatically
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# from the labels in the pod template if not set,
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# but we are specifying the selector here to
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# demonstrate its usage.
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selector:
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matchLabels:
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tier: frontend
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matchExpressions:
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- {key: tier, operator: In, values: [frontend]}
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template:
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metadata:
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labels:
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app: guestbook
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tier: frontend
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spec:
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containers:
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- name: php-redis
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image: gcr.io/google_samples/gb-frontend:v3
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resources:
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requests:
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cpu: 100m
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memory: 100Mi
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env:
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- name: GET_HOSTS_FROM
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value: dns
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# If your cluster config does not include a dns service, then to
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# instead access environment variables to find service host
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# info, comment out the 'value: dns' line above, and uncomment the
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# line below.
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# value: env
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ports:
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- containerPort: 80
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```
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