Kubernetes default-scheduler 0/2 nodes are available: 2 node(s

问题

  这个问题其实很简单，因为deployment（或其他控制器）或Pod的yaml文件中使用了nodeSelector,例如：下面的这个yaml文件：

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app.kubernetes.io/name: kube-state-metrics
    app.kubernetes.io/version: v1.8.0
  name: kube-state-metrics
  namespace: monitoring
spec:
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: kube-state-metrics
  template:
    metadata:
      labels:
        app.kubernetes.io/name: kube-state-metrics
        app.kubernetes.io/version: v1.8.0
    spec:
      containers:
      - image: quay.io/coreos/kube-state-metrics:v1.8.0
        livenessProbe:
          httpGet:
            path: /healthz
            port: 8080
          initialDelaySeconds: 5
          timeoutSeconds: 5
        name: kube-state-metrics
        ports:
        - containerPort: 8080
          name: http-metrics
        - containerPort: 8081
          name: telemetry
        readinessProbe:
          httpGet:
            path: /
            port: 8081
          initialDelaySeconds: 5
          timeoutSeconds: 5
      nodeSelector:
        kubernetes.io/os: linux
      serviceAccountName: kube-state-metrics

倒数第三行指定了nodeSelector，如果当前集群中没有一个node的label符合这个nodeSelector，则在describepod资源时显示：

Warning  FailedScheduling  18s (x2 over 18s)  default-scheduler  0/2 nodes are available: 2 node(s) didn't match node selector

解决问题

1. 给需要调度的node加上对应标签

# 相对上面这个Yaml文件的例子
kubectl label nodes node_name kubernetes.io/os=linux

2. 删除Yaml文件中的nodeSelector，如果对节点没有要求的话，直接删除节点选择器即可