英文:
How to make kube-proxy is distribute the load evently?
问题
我有一个ClusterIP服务，用于在内部分发负载到2个POD。
负载没有均匀分发到这2个POD上。
如何使负载均匀分发？
英文:
I have a ClusterIP Service which is used to distribute load to 2 PODs internally.
The load is not distributed evenly across the PODs.
How to make the load distributed evenly ?
答案1
得分: 1
Kubernetes使用iptables来在Pod之间分发负载（默认情况下使用iptables代理模式）。
如果有2个Pod，负载会均匀分布，概率为0.5（50%）。因为它不使用循环轮询，后端Pod是随机选择的。在较长的时间范围内，它将保持均匀。
如果有3个Pod，概率将变为1/3（33%），对于4个Pod，概率为1/4，依此类推。
要检查它，您可以运行 sudo iptables-save。
2个Pod的示例输出（对于nginx服务）：
sudo iptables-save | grep nginx
-A KUBE-NODEPORTS -p tcp -m comment --comment "default/nginx:" -m tcp --dport 31554 -j KUBE-SVC-4N57TFCL4MD7ZTDA //KUBE-SVC-4N57TFCL4MD7ZTDA是nginx服务的标签
sudo iptables-save | grep KUBE-SVC-4N57TFCL4MD7ZTDA
-A KUBE-SVC-4N57TFCL4MD7ZTDA -m statistic --mode random --probability 0.50000000000 -j KUBE-SEP-SOWYYRHSSTWLCRDY
如果您希望确保负载均匀分布，使用循环轮询算法，您可以使用IPVS，默认情况下使用rr（循环轮询）。它作为集群前端的负载均衡器，将基于TCP和UDP的服务的请求引导到真实服务器，并使真实服务器的服务出现为单个IP地址上的虚拟服务。它在由local-up、kubeadm和GCE创建的集群上是受支持的。
英文:
Kubernetes uses iptables to distribute the load between pods (iptables proxy mode by default).
If you have 2 pods, it is distributed evenly with 0.5 (50%) probability. Because it is not using round-robin, the backend pod is chosen randomly. It will be even in a longer time-frame.
If there would be 3 pods, probability will change to 1/3 (33%), for 4 pods 1/4 and so on.
To check it you can run sudo iptables-save.
Example output for 2 pods (for nginx service):
sudo iptables-save | grep nginx
-A KUBE-NODEPORTS -p tcp -m comment --comment "default/nginx:" -m tcp --dport 31554 -j KUBE-SVC-4N57TFCL4MD7ZTDA //KUBE-SVC-4N57TFCL4MD7ZTDA is a tag for nginx service
sudo iptables-save | grep KUBE-SVC-4N57TFCL4MD7ZTDA
-A KUBE-SVC-4N57TFCL4MD7ZTDA -m statistic --mode random --probability 0.50000000000 -j KUBE-SEP-SOWYYRHSSTWLCRDY
If you want to make sure load is distributed evenly using round-robin algorithm you can use IPVS which by default uses rr (round-robin). It works as load balancer in front of a cluster and directs requests for TCP- and UDP-based services to the real servers, and make services of the real servers appear as virtual services on a single IP address. It is supported on cluster created by local-up, kubeadm and GCE.
答案2
得分: 0
kube-proxy 在用户空间代理模式下通过轮询方式选择后端 Pod。
kube-proxy 在 iptables 模式下随机选择后端 Pod。
英文:
kube-proxy in User space proxy mode chooses backend pod via round robin fashion.
kube-proxy in iptables mode chooses the backend pod randomly.
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