对Pod中同一应用的多个容器进行负载平衡 [英] Load balancing to multiple containers of same app in a pod

问题描述

我有一个场景，我需要在同一容器中运行一个应用程序容器的两个实例. 我将它们设置为在不同的端口上侦听.以下是部署清单的外观. 使用预期数量的容器，Pod可以很好地启动. 我什至可以从其他Pod连接到podIP上的两个端口.

I have a scenario where I need to have two instances of an app container run within the same pod. I have them setup to listen on different ports. Below is how the Deployment manifest looks like. The Pod launches just fine with the expected number of containers. I can even connect to both ports on the podIP from other pods.

kind: Deployment
metadata:
  labels:
    service: app1-service
  name: app1-dep
  namespace: exp
spec:
  template:
    spec:
      contianers:
        - image: app1:1.20
          name: app1
          ports:
          - containerPort: 9000
            protocol: TCP
        - image: app1:1.20
          name: app1-s1
          ports:
          - containerPort: 9001
            protocol: TCP

我什至可以为容器的每个端口创建两个不同的服务，而且效果也很好. 我可以分别访问这两个服务，最后到达Pod内的相应容器.

I can even create two different Services one for each port of the container, and that works great as well. I can individually reach both Services and end up on the respective container within the Pod.

apiVersion: v1
kind: Service
metadata:
  name: app1
  namespace: exp
spec:
  ports:
  - name: http
    port: 80
    protocol: TCP
    targetPort: 9000
  selector:
    service: app1-service
  sessionAffinity: None
  type: ClusterIP

---
apiVersion: v1
kind: Service
metadata:
  name: app1-s1
  namespace: exp
spec:
  ports:
  - name: http
    port: 80
    protocol: TCP
    targetPort: 9001
  selector:
    service: app1-service
  sessionAffinity: None
  type: ClusterIP

我希望单个服务背后的两个容器实例在两个容器之间轮循. 我该如何实现?在服务领域内可能吗?还是我需要探索类似这样的入口?

I want both the instances of the container behind a single service, that round robins between both the containers. How can I achieve that? Is it possible within the realm of services? Or would I need to explore ingress for something like this?

推荐答案

Kubernetes服务具有三种代理模式:iptables(默认设置)，userspace，IPVS.

Kubernetes services has three proxy modes: iptables (is the default), userspace, IPVS.

• Userspace:是较旧的方法，它是循环分发的唯一方法.
• Iptables:是默认设置，并随机选择一个吊舱并坚持使用.
• IPVS:具有多种分发流量的方法，但是首先您必须使用以下命令将其安装在您的节点上，例如在centos节点上: yum install ipvsadm，然后使其可用.

• Userspace: is the older way and it distribute in round-robin as the only way.
• Iptables: is the default and select at random one pod and stick with it.
• IPVS: Has multiple ways to distribute traffic but first you have to install it on your node, for example on centos node with this command: yum install ipvsadm and then make it available.

就像我说的那样，默认情况下，Kubernetes服务没有轮询. 要激活IPVS，您必须向kube-proxy添加一个参数

Like i said, Kubernetes service by default has no round-robin. To activate IPVS you have to add a parameter to kube-proxy

--proxy-mode=ipvs

--ipvs-scheduler=rr(用于选择循环)

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