42.3. 将集群容量作为 Pod 的作业运行

创建集群角色：

$ cat << EOF| oc create -f -
kind: ClusterRole
apiVersion: v1
metadata:
  name: cluster-capacity-role
rules:
- apiGroups: [""]
  resources: ["pods", "nodes", "persistentvolumeclaims", "persistentvolumes", "services"]
  verbs: ["get", "watch", "list"]
EOF

创建服务帐户：

$ oc create sa cluster-capacity-sa

将角色添加到服务帐户：

$ oc adm policy add-cluster-role-to-user cluster-capacity-role \
    system:serviceaccount:default:cluster-capacity-sa 1

定义并创建 pod 规格：

apiVersion: v1
kind: Pod
metadata:
  name: small-pod
  labels:
    app: guestbook
    tier: frontend
spec:
  containers:
  - name: php-redis
    image: gcr.io/google-samples/gb-frontend:v4
    imagePullPolicy: Always
    resources:
      limits:
        cpu: 150m
        memory: 100Mi
      requests:
        cpu: 150m
        memory: 100Mi

集群容量分析使用名为 cluster-capacity-configmap 的 ConfigMap 挂载到卷中，从而将输入 pod 规格文件 pod.yaml 挂载到卷 test-volume 的路径 /test-pod 上。

如果还没有创建 ConfigMap，请在创建作业前创建：

$ oc create configmap cluster-capacity-configmap \
    --from-file=pod.yaml

使用以下作业规格文件示例创建作业：

apiVersion: batch/v1
kind: Job
metadata:
  name: cluster-capacity-job
spec:
  parallelism: 1
  completions: 1
  template:
    metadata:
      name: cluster-capacity-pod
    spec:
        containers:
        - name: cluster-capacity
          image: registry.redhat.io/openshift3/ose-cluster-capacity
          imagePullPolicy: "Always"
          volumeMounts:
          - mountPath: /test-pod
            name: test-volume
          env:
          - name: CC_INCLUSTER 1
            value: "true"
          command:
          - "/bin/sh"
          - "-ec"
          - |
            /bin/cluster-capacity --podspec=/test-pod/pod.yaml --verbose
        restartPolicy: "Never"
        serviceAccountName: cluster-capacity-sa
        volumes:
        - name: test-volume
          configMap:
            name: cluster-capacity-configmap

以 pod 中作业的方式运行集群容量镜像：

$ oc create -f cluster-capacity-job.yaml

检查作业日志，以查找在集群中可调度的 pod 数量：

$ oc logs jobs/cluster-capacity-job
small-pod pod requirements:
        - CPU: 150m
        - Memory: 100Mi

The cluster can schedule 52 instance(s) of the pod small-pod.

Termination reason: Unschedulable: No nodes are available that match all of the
following predicates:: Insufficient cpu (2).

Pod distribution among nodes:
small-pod
        - 192.168.124.214: 26 instance(s)
        - 192.168.124.120: 26 instance(s)