How to replace Iptables with Ipvs in a Kubernetes cluster

Everyone knows that in Kubernetes, kube-proxy is a network proxy. Its main responsibility is to provide load balancing and service discovery functions for services in the cluster. kube-proxy has different operating modes, among which iptables mode and ipvs mode are two common modes. In iptables mode, kube-proxy implements load balancing and service discovery through iptables rules, while ipvs mode uses the IPVS (IP Virtual Server) technology in the Linux kernel to achieve more efficient load balancing. Choosing the appropriate mode depends on your cluster's needs and performance requirements. The iptables mode is suitable for small clusters, while the ipvs mode is more suitable for large clusters because it provides better performance and scalability. Therefore, when deploying a Kubernetes cluster, it needs to be based on actual needs and regulations

iptables and ipvs are network proxy technologies in the Linux kernel, used for load balancing and service discovery. The difference between them is that iptables is a rule-based firewall, while ipvs is a network layer-based load balancing tool.

Different implementation methods

The implementation based on iptables rules is to add a set of rules on each node to achieve load balancing and service discovery; while ipvs is a kernel-level load balancing technology that can handle network proxies more efficiently. Iptables mainly focuses on filtering and forwarding network packets, while ipvs focuses on load balancing and traffic distribution, which can manage and optimize network resources more effectively. By reasonably combining the two, network traffic can be better balanced and efficiently processed, and the overall performance and stability of the system can be improved.

Different performance

Under high load conditions, kube-proxy in ipvs mode performs better because it performs network load balancing based on the kernel level and is more efficient. However, in some scenarios, Iptables mode may also achieve better performance.

Different functions

Kube-proxy in Iptables mode Before Kubernetes version 1.16, using iptables to implement port forwarding could only implement TCP-based load balancing and service discovery, and could not support four-layer load balancing. In Kubernetes version 1.16, the iptables-nat mode is added, which can support four-layer load balancing. In contrast, ipvs mode supports TCP, UDP, SCTP and four-layer load balancing, and supports multiple load balancing algorithms such as Online Hashed, IP Hash, Round Robin and Least Connection.

One disadvantage of iptables is that it operates at the kernel level. When iptables rules are too cumbersome, it may affect system performance. In addition, because iptables rules are centralized in the kernel, they are relatively difficult to modify.

In the Kubernetes system, the kubeadm management tool will select the ipvs mode by default to handle kube-proxy. At the same time, Kubernetes also provides a variety of exception handling mechanisms, such as automatic pull-up, rollback, failover, etc., to ensure the reliability of the system. , high availability and fault tolerance, thus avoiding possible problems that may arise during iptables processing and improving the performance of the entire system in terms of fault handling and fault tolerance.

The operation is on all nodes

Enable kernel support

<code>cat >> /etc/sysctl.conf/etc/sysconfig/modules/ipvs.modules</code>

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