kubernetes - How can I distribute a deployment across nodes?

Question

I have a Kubernetes deployment that looks something like this (replaced names and other things with '....'):

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# and an empty file will abort the edit. If an error occurs while saving this file will be
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apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "3"
    kubernetes.io/change-cause: kubectl replace deployment ....
      -f - --record
  creationTimestamp: 2016-08-20T03:46:28Z
  generation: 8
  labels:
    app: ....
  name: ....
  namespace: default
  resourceVersion: "369219"
  selfLink: /apis/extensions/v1beta1/namespaces/default/deployments/....
  uid: aceb2a9e-6688-11e6-b5fc-42010af000c1
spec:
  replicas: 2
  selector:
    matchLabels:
      app: ....
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: ....
    spec:
      containers:
      - image: gcr.io/..../....:0.2.1
        imagePullPolicy: IfNotPresent
        name: ....
        ports:
        - containerPort: 8080
          protocol: TCP
        resources:
          requests:
            cpu: "0"
        terminationMessagePath: /dev/termination-log
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      securityContext: {}
      terminationGracePeriodSeconds: 30
status:
  availableReplicas: 2
  observedGeneration: 8
  replicas: 2
  updatedReplicas: 2

The problem I'm observing is that Kubernetes places both replicas (in the deployment I've asked for two) on the same node. If that node goes down, I lose both containers and the service goes offline.

What I want Kubernetes to do is to ensure that it doesn't double up containers on the same node where the containers are the same type - this only consumes resources and doesn't provide any redundancy. I've looked through the documentation on deployments, replica sets, nodes etc. but I couldn't find any options that would let me tell Kubernetes to do this.

Is there a way to tell Kubernetes how much redundancy across nodes I want for a container?

EDIT: I'm not sure labels will work; labels constrain where a node will run so that it has access to local resources (SSDs) etc. All I want to do is ensure no downtime if a node goes offline.

question from:https://stackoverflow.com/questions/39092090/how-can-i-distribute-a-deployment-across-nodes

Answer 1

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