• Kubernetes IPVS和IPTABLES

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    Kubernetes IPVS和IPTABLES

    什么是IPVS

    IPVS（IP Virtual Server，IP虚拟服务器）实现了传输层的负载平衡，通常称为4 LAN（四层局域网）交换，是Linux内核的一部分。

    IPVS在主机上运行，在真实服务器集群前面充当负载平衡器。IPVS可以将基于 TCP 和 UDP 的服务请求定向到真实服务器上。

    IPVS vs IPTABLES

    IPVS 模式在 Kubernetes v1.8中引入，在v1.9中成为测试版，在v1.11中成为GA。
    IPTABLES模式是在v1.1版本中加入的，从v1.2版本开始成为默认的操作模式。

    IPVS和IPTABLES都是基于netfilter的。IPVS模式和IPTABLES模式的区别如下：

    1. IPVS为大型集群提供更好的可扩展性和性能。

    2. IPVS比IPTABLES支持更复杂的负载平衡算法（最小负载、最小连接、定位、加权等）。

    3. IPVS 支持服务器健康检查和连接重试等。

    IPVS 对 IPTABLES 的依赖

    IPVS代理使用IPTABLES做数据包过滤、SNAT或伪装。具体来说，IPVS代理将使用ipset来存储需要DROP或做伪装的流量的源地址或目的地址，以确保无论我们有多少服务，IPTABLES规则的数量不变。

    下面是IPVS代理服务器使用的ipset集的表格。

    set namemembersusage
    KUBE-CLUSTER-IPAll service IP + portMark-Masq for cases that masquerade-all=true or clusterCIDR specified
    KUBE-LOOP-BACKAll service IP + port + IPmasquerade for solving hairpin purpose
    KUBE-EXTERNAL-IPservice external IP + portmasquerade for packages to external IPs
    KUBE-LOAD-BALANCERload balancer ingress IP + portmasquerade for packages to load balancer type service
    KUBE-LOAD-BALANCER-LOCALLB ingress IP + port with externalTrafficPolicy=localaccept packages to load balancer with externalTrafficPolicy=local
    KUBE-LOAD-BALANCER-FWload balancer ingress IP + port with loadBalancerSourceRangespackage filter for load balancer with loadBalancerSourceRanges specified
    KUBE-LOAD-BALANCER-SOURCE-CIDRload balancer ingress IP + port + source CIDRpackage filter for load balancer with loadBalancerSourceRanges specified
    KUBE-NODE-PORT-TCPnodeport type service TCP portmasquerade for packets to nodePort(TCP)
    KUBE-NODE-PORT-LOCAL-TCPnodeport type service TCP port with externalTrafficPolicy=localaccept packages to nodeport service with externalTrafficPolicy=local
    KUBE-NODE-PORT-UDPnodeport type service UDP portmasquerade for packets to nodePort(UDP)
    KUBE-NODE-PORT-LOCAL-UDPnodeport type service UDP port with externalTrafficPolicy=localaccept packages to nodeport service with externalTrafficPolicy=local

    在以下情况下，IPVS 代理将依赖 IPTABLES。

    1. kube-proxy以–masquerade-all=true启动

    如果kube-proxy以--masquerade-all=true启动，IPVS代理将伪装所有访问服务集群IP的流量，这与IPTABLES代理的行为相同。假设kube-proxy指定了标志--masquerade-all=true，那么IPVS代理安装的IPTABLES应该如下所示：

    # iptables -t nat -nL

Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-POSTROUTING  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes postrouting rules */

Chain KUBE-MARK-MASQ (2 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x4000

Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOOP-BACK dst,dst,src

Chain KUBE-SERVICES (2 references)
target     prot opt source               destination
KUBE-MARK-MASQ  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-CLUSTER-IP dst,dst
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-CLUSTER-IP dst,dst

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    2. 在kube-proxy启动时指定集群CIDR

    如果kube-proxy以--cluster-cidr=启动，IPVS代理将伪装访问服务集群IP的非集群流量，其行为与IPTABLES代理相同。假设kube-proxy提供的集群cidr是10.244.16.0/24，那么IPVS代理安装的IPTABLES应该如下所示。

    # iptables -t nat -nL

Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-POSTROUTING  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes postrouting rules */

Chain KUBE-MARK-MASQ (3 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x4000

Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOOP-BACK dst,dst,src

Chain KUBE-SERVICES (2 references)
target     prot opt source               destination
KUBE-MARK-MASQ  all  -- !10.244.16.0/24       0.0.0.0/0            match-set KUBE-CLUSTER-IP dst,dst
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-CLUSTER-IP dst,dst

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    3. loadBalancer类型的服务

    对于loadBalancer类型的服务，IPVS代理将安装IPTABLES与ipset KUBE-LOAD-BALANCER匹配。特别是当服务的LoadBalancerSourceRanges被指定或指定externalTrafficPolicy=local时，IPVS代理将创建ipset集KUBE-LOAD-BALANCER-LOCAL/KUBE-LOAD-BALANCER-FW/KUBE-LOAD-BALANCER-SOURCE-CIDR并相应地安装IPTABLES，它应该看起来像下面所示。

    # iptables -t nat -nL

Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-POSTROUTING  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes postrouting rules */

Chain KUBE-FIREWALL (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOAD-BALANCER-SOURCE-CIDR dst,dst,src
KUBE-MARK-DROP  all  --  0.0.0.0/0            0.0.0.0/0

Chain KUBE-LOAD-BALANCER (1 references)
target     prot opt source               destination
KUBE-FIREWALL  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOAD-BALANCER-FW dst,dst
RETURN     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOAD-BALANCER-LOCAL dst,dst
KUBE-MARK-MASQ  all  --  0.0.0.0/0            0.0.0.0/0

Chain KUBE-MARK-DROP (1 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x8000

Chain KUBE-MARK-MASQ (2 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x4000

Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOOP-BACK dst,dst,src

Chain KUBE-SERVICES (2 references)
target     prot opt source               destination
KUBE-LOAD-BALANCER  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOAD-BALANCER dst,dst
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOAD-BALANCER dst,dst

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    4. NodePort类型的服务

    对于NodePort类型的服务，IPVS代理将安装IPTABLES与ipset KUBE-NODE-PORT-TCP/KUBE-NODE-PORT-UDP的匹配。当指定externalTrafficPolicy=local时，IPVS代理将创建ipset集KUBE-NODE-PORT-LOCAL-TCP/KUBE-NODE-PORT-LOCAL-UDP并相应地安装IPTABLES，这应该是如下所示的：

    假设服务的TCP类型为nodePort。

    Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-POSTROUTING  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes postrouting rules */

Chain KUBE-MARK-MASQ (2 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x4000

Chain KUBE-NODE-PORT (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-NODE-PORT-LOCAL-TCP dst
KUBE-MARK-MASQ  all  --  0.0.0.0/0            0.0.0.0/0

Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOOP-BACK dst,dst,src

Chain KUBE-SERVICES (2 references)
target     prot opt source               destination
KUBE-NODE-PORT  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-NODE-PORT-TCP dst

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    5. 指定externalIP的服务

    对于指定了外部IP的服务，IPVS代理将安装IPTABLES与ipset KUBE-EXTERNAL-IP匹配，假设我们有指定了外部IP的服务，IPTABLES规则应该如下所示：

    Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-POSTROUTING  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes postrouting rules */

Chain KUBE-MARK-MASQ (2 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x4000

Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOOP-BACK dst,dst,src

Chain KUBE-SERVICES (2 references)
target     prot opt source               destination
KUBE-MARK-MASQ  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-EXTERNAL-IP dst,dst
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-EXTERNAL-IP dst,dst PHYSDEV match ! --physdev-is-in ADDRTYPE match src-type !LOCAL
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-EXTERNAL-IP dst,dst ADDRTYPE match dst-type LOCAL

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    Kubernetes使用IPVS

    安装IPVS

    CentOS

    yum install ipset ipvsadm -y

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    Ubuntu

    apt-get install ipset ipvsadm -y


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    设置

    cat > /etc/sysconfig/modules/ipvs.modules <
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  • 原文地址：https://blog.csdn.net/qq_52716296/article/details/127768504