理解pod分配 - kubernetes集群（AWS）

Question

我正在创建部署的四个副本。关注的是所有pod都会转到不同的节点。我没有定义PodAffinity。我的群集中有4个节点和3个主节点。我有一个部署已经在一个pod（只有一个副本）上运行，它占用了一个节点。现在，我正在尝试部署另一个部署（4个副本），但失败了。为什么不在现有节点上传播pod而不是失败？

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: product-download-deployment-sslsigned-live
spec:
  replicas: 4
  template:
    metadata:
      labels:
        app: product-download-service-sslsigned-live
        color: blue
    spec:
      hostNetwork: true
      containers:
      - name: product-download-api
        image: 5648601107.dkr.ecr.us-west-2.amazonaws.com/pd_repo_8080
        ports:
        - containerPort: 8080
        volumeMounts:
        - name: pd-log-volume
          mountPath: /tmp/pd_log
        readinessProbe:
          tcpSocket:
           port: 8080
          initialDelaySeconds: 5
          periodSeconds: 10
        livenessProbe:
          tcpSocket:
           port: 8080
          initialDelaySeconds: 15
          periodSeconds: 20    
      - name: nginxhttps
        image: 5648601107.dkr.ecr.us-west-2.amazonaws.com/nginx_ssl
        ports:
        - containerPort: 443
        readinessProbe:
          httpGet:
            path: /product-downloads/health
            port: 443
            scheme: HTTPS
          initialDelaySeconds: 5
          periodSeconds: 10
        livenessProbe:
          httpGet:
            path: /product-downloads/health
            port: 443
            scheme: HTTPS
          initialDelaySeconds: 15
          periodSeconds: 20 
      volumes:
       - name: pd-log-volume
         hostPath:
           path: /var/log/pd
           type: DirectoryOrCreate