环境
- Kubernetes v1.14.6
- Etcd 3.3.12
- Docker 18.09.9
K8s service
service是一堆相同label pod集合的抽象，通过selector标签来匹配pod; 服务间访问也通过service(域名)，用service可以避免pod ip迁移发生变化；service对象也会对应多个 endpoint对象，endpoint用于服务发现；无论是service、endpoint都是逻辑概念，真正路由转发是 kube-proxy，通常以daemonset形式运行于集群中，kube-proxy会watch service、endpoint变化， 生成/改变宿主机上的iptables/ipvs转发规则
service类型：
- ClusterIP(默认)
- NodePort
- LoadBalancer
- ExternelName
headless service: 没有clusterIP的service, 给应用集群的每个pod分配一个dns域名，pod之间 用该域名直接访问，mysql/redis等集群都是这种方式
提下ingress, ingress不是service类型，作用于7层，是外部访问内部应用的入口； 不同的域名/路径来匹配不同的service
kube-proxy模式
kube-proxy模式：
- userspace(这里不介绍，有了iptables)
- iptables(userspace的改进)
- ipvs
- kernelspace(windows下使用)
IPVS vs. IPTABLES:
IPVS模式在Kubernetes v1.8中引入，在v1.9中处于beta版本，在v1.11中处于GA版本。 IPTABLES模式已在v1.1中添加，并成为v1.2之后的默认操作模式。 IPVS和IPTABLES均基于netfilter。
IPVS模式和IPTABLES模式之间的差异如下：
- IPVS为大型群集提供了更好的可伸缩性和性能。
- 与IPTABLES相比，IPVS支持更复杂的负载平衡算法（最低负载，最少连接，局部性，加权等）。
- IPVS支持服务器运行状况检查和连接重试等。
- 底层数据结构：IPTABLES使用链表，IPVS使用哈希表
iptables模式
iptables 5张表5条链
5张表:
- filter: 过滤某个链上的数据包
- nat: 网络地址转换，转换数据包的源地址和目的地址
- mangle: 修改数据包的IP头部信息
- raw: iptables本身是有状态的，对数据包有链接追踪(/proc/net/nf_conntrack可看到)，raw 可以用来消除这种追踪机制
- security: 数据包上使用selinux
5条链:
- PREROUTING: 数据包进入内核网络模块之后, 获得路由之前(可进行DNAT)
- INPUT: 数据包被决定路由到本机之后, 一般处理本地进程的数据包, 目的地址是本机
- FORWARD: 数据包被决定路由到其他主机之后, 一般处理转发到其它主机/网络命名空间的数据包
- OUTPUT: 离开本机的数据包进入内核网络模块之后, 一般处理本地进程的输出数据包, 源地址是本机
- POSTROUTING: 对于离开本机或者FORWARD的数据包, 当数据包被发送到网卡之前(可进行SNAT)
iptables的表和链是有顺序的，工作流程如下:
kube-proxy iptables模式使用了filter和nat表，并定义了很多自定义链
filter表自定义链:
- KUBE-SERVICES
- KUBE-EXTERNAL-SERVICES
- KUBE-FIREWALL
nat表自定义链:
- KUBE-HOSTPORTS
- KUBE-SERVICES
- KUBE-POSTROUTING
- KUBE-MARK-DROP
- KUBE-MARK-MASQ
- KUBE-NODEPORTS
- KUBE-SVC-XXX
- KUBE-SEP-XXX
具体来看kube-proxy生成的iptables规则, 以一个httpbin服务为例
httpbin的k8s manifest
# vim httpbin.yaml
---
apiVersion: v1
kind: Service
metadata:
name: httpbin
labels:
app: httpbin
spec:
ports:
- name: http
port: 80
targetPort: 80
selector:
app: httpbin
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: httpbin
spec:
replicas: 1
selector:
matchLabels:
app: httpbin
template:
metadata:
labels:
app: httpbin
spec:
containers:
- image: docker.io/kennethreitz/httpbin
name: httpbin
ports:
- containerPort: 80
# kubectl apply -f httpbin.yaml
service/httpbin created
deployment.apps/httpbin created
# kubectl get svc -l app=httpbin
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
httpbin ClusterIP 172.20.255.90 <none> 80/TCP 2m38s
# kubectl get pod -l app=httpbin
NAME READY STATUS RESTARTS AGE
httpbin-896cb847-vwpg2 1/1 Running 0 2m45s
clusterIP为172.20.255.90，pod单副本
clusterIP service类型
pod间访问clusterIP的iptables规则链顺序为：(对照上面的iptables工作流程图)
PREROUTING -> KUBE-SERVICES -> KUBE-SVC-XXX -> KUBE-SEP-XXX
1. 进入PREROUTING的规则都转发到KUBE-SERVICES, 不符合KUBE-HOSTPORTS的条件
-A PREROUTING -m comment --comment "kube hostport portals" -m addrtype --dst-type LOCAL -j KUBE-HOSTPORTS
-A PREROUTING -m comment --comment "kubernetes service portals" -j KUBE-SERVICES
2. 访问clusterIP为172.20.255.90的都转发至KUBE-SVC-FREKB6WNWYJLKTHC
-A KUBE-SERVICES -d 172.20.255.90/32 -p tcp -m comment --comment "default/httpbin:http cluster IP" -m tcp --dport 80 -j KUBE-SVC-FREKB6WNWYJLKTHC
3. 进入KUBE-SVC-FREKB6WNWYJLKTHC的都转发至KUBE-SEP-PEA6WHECIZEOX47B
-A KUBE-SVC-FREKB6WNWYJLKTHC -j KUBE-SEP-PEA6WHECIZEOX47B
4. KUBE-SEP-PEA6WHECIZEOX47B对应endpoint中的172.20.0.40:80
-A KUBE-SEP-PEA6WHECIZEOX47B -s 172.20.0.40/32 -j KUBE-MARK-MASQ
-A KUBE-SEP-PEA6WHECIZEOX47B -p tcp -m tcp -j DNAT --to-destination 172.20.0.40:80
# 0x4000是kube-proxy的数据包放行标记, 0x8000是数据包丢弃标记
-A KUBE-MARK-DROP -j MARK --set-xmark 0x8000/0x8000
-A KUBE-MARK-MASQ -j MARK --set-xmark 0x4000/0x4000
httpbin pod副本数扩到2，观察iptables KUBE-SVC-，KUBE-SEP-链的变化
# kubectl scale deployment httpbin --replicas=2
deployment.extensions/httpbin scaled
-A KUBE-SVC-FREKB6WNWYJLKTHC -m statistic --mode random --probability 0.50000000000 -j KUBE-SEP-PEA6WHECIZEOX47B
-A KUBE-SVC-FREKB6WNWYJLKTHC -j KUBE-SEP-UHAR347MOFCEOPWZ
-A KUBE-SEP-UHAR347MOFCEOPWZ -s 172.20.1.183/32 -j KUBE-MARK-MASQ
-A KUBE-SEP-UHAR347MOFCEOPWZ -p tcp -m tcp -j DNAT --to-destination 172.20.1.183:80
httpbin pod副本数扩到3，观察iptables KUBE-SVC-，KUBE-SEP-链的变化
# 3副本, 每个都是1/3概率
-A KUBE-SVC-FREKB6WNWYJLKTHC -m statistic --mode random --probability 0.33332999982 -j KUBE-SEP-PEA6WHECIZEOX47B
# probability=(1-0.33332999982)/2=0.50000000000
-A KUBE-SVC-FREKB6WNWYJLKTHC -m statistic --mode random --probability 0.50000000000 -j KUBE-SEP-JXNDCT5ED2555YYJ
-A KUBE-SVC-FREKB6WNWYJLKTHC -j KUBE-SEP-UHAR347MOFCEOPWZ
-A KUBE-SEP-UHAR347MOFCEOPWZ -s 172.20.1.183/32 -j KUBE-MARK-MASQ
-A KUBE-SEP-UHAR347MOFCEOPWZ -p tcp -m tcp -j DNAT --to-destination 172.20.1.183:80
nodePort service类型
httpbin svc修改为nodePort类型
[root@ice ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
httpbin NodePort 172.20.255.90 <none> 80:11387/TCP
非本地访问nodePort的iptables规则链顺序为:
PREROUTING -> KUBE-SERVICES -> KUBE-NODEPORTS -> KUBE-SVC-XXX -> KUBE-SEP-XXX
1. 进入PREROUTING的规则都转发到KUBE-SERVICES, 不符合KUBE-HOSTPORTS的条件
-A PREROUTING -m comment --comment "kube hostport portals" -m addrtype --dst-type LOCAL -j KUBE-HOSTPORTS
-A PREROUTING -m comment --comment "kubernetes service portals" -j KUBE-SERVICES
2. 优先处理clusterIP
-A KUBE-SERVICES -d 172.20.255.90/32 -p tcp -m comment --comment "default/httpbin:http cluster IP" -m tcp --dport 80 -j KUBE-SVC-FREKB6WNWYJLKTHC
3. 进入KUBE-SERVICES的规则, 优先处理clusterIP，最后都转发到KUBE-NODEPORTS
-A KUBE-SERVICES -m comment --comment "kubernetes service nodeports; NOTE: this must be the last rule in this chain" -m addrtype --dst-type LOCAL -j KUBE-NODEPORTS
4. 接下来就跟上述clusterIP类型的流程一样了
-A KUBE-NODEPORTS -p tcp -m comment --comment "default/httpbin:http" -m tcp --dport 11387 -j KUBE-MARK-MASQ
-A KUBE-NODEPORTS -p tcp -m comment --comment "default/httpbin:http" -m tcp --dport 11387 -j KUBE-SVC-FREKB6WNWYJLKTHC
5.
-A KUBE-SVC-FREKB6WNWYJLKTHC -m statistic --mode random --probability 0.33332999982 -j KUBE-SEP-PEA6WHECIZEOX47B
-A KUBE-SVC-FREKB6WNWYJLKTHC -m statistic --mode random --probability 0.50000000000 -j KUBE-SEP-JXNDCT5ED2555YYJ
-A KUBE-SVC-FREKB6WNWYJLKTHC -j KUBE-SEP-UHAR347MOFCEOPWZ
6.
-A KUBE-SEP-PEA6WHECIZEOX47B -s 172.20.0.40/32 -j KUBE-MARK-MASQ
-A KUBE-SEP-PEA6WHECIZEOX47B -p tcp -m tcp -j DNAT --to-destination 172.20.0.40:80
-A KUBE-SEP-JXNDCT5ED2555YYJ -s 172.20.0.41/32 -j KUBE-MARK-MASQ
-A KUBE-SEP-JXNDCT5ED2555YYJ -p tcp -m tcp -j DNAT --to-destination 172.20.0.41:80
-A KUBE-SEP-UHAR347MOFCEOPWZ -s 172.20.1.183/32 -j KUBE-MARK-MASQ
-A KUBE-SEP-UHAR347MOFCEOPWZ -p tcp -m tcp -j DNAT --to-destination 172.20.1.183:80
本地访问nodePort的iptables规则链顺序为:
OUTPUT -> KUBE-SERVICES -> KUBE-NODEPORTS -> KUBE-SVC-XXX -> KUBE-SEP-XXX
1. 进入PREROUTING的规则都转发到KUBE-SERVICES都转发至KUBE-SERVICES
-A OUTPUT -m comment --comment "kube hostport portals" -m addrtype --dst-type LOCAL -j KUBE-HOSTPORTS
-A OUTPUT -m comment --comment "kubernetes service portals" -j KUBE-SERVICES
2. 优先处理clusterIP
-A KUBE-SERVICES -d 172.20.255.90/32 -p tcp -m comment --comment "default/httpbin:http cluster IP" -m tcp --dport 80 -j KUBE-SVC-FREKB6WNWYJLKTHC
3. 进入KUBE-SERVICES的规则, 优先处理clusterIP，最后都转发到KUBE-NODEPORTS
-A KUBE-SERVICES -m comment --comment "kubernetes service nodeports; NOTE: this must be the last rule in this chain" -m addrtype --dst-type LOCAL -j KUBE-NODEPORTS
4. 接下来就跟上述clusterIP类型的流程一样了
-A KUBE-NODEPORTS -p tcp -m comment --comment "default/httpbin:http" -m tcp --dport 11387 -j KUBE-MARK-MASQ
-A KUBE-NODEPORTS -p tcp -m comment --comment "default/httpbin:http" -m tcp --dport 11387 -j KUBE-SVC-FREKB6WNWYJLKTHC
5.
-A KUBE-SVC-FREKB6WNWYJLKTHC -m statistic --mode random --probability 0.33332999982 -j KUBE-SEP-PEA6WHECIZEOX47B
-A KUBE-SVC-FREKB6WNWYJLKTHC -m statistic --mode random --probability 0.50000000000 -j KUBE-SEP-JXNDCT5ED2555YYJ
-A KUBE-SVC-FREKB6WNWYJLKTHC -j KUBE-SEP-UHAR347MOFCEOPWZ
6.
-A KUBE-SEP-PEA6WHECIZEOX47B -s 172.20.0.40/32 -j KUBE-MARK-MASQ
-A KUBE-SEP-PEA6WHECIZEOX47B -p tcp -m tcp -j DNAT --to-destination 172.20.0.40:80
-A KUBE-SEP-JXNDCT5ED2555YYJ -s 172.20.0.41/32 -j KUBE-MARK-MASQ
-A KUBE-SEP-JXNDCT5ED2555YYJ -p tcp -m tcp -j DNAT --to-destination 172.20.0.41:80
-A KUBE-SEP-UHAR347MOFCEOPWZ -s 172.20.1.183/32 -j KUBE-MARK-MASQ
-A KUBE-SEP-UHAR347MOFCEOPWZ -p tcp -m tcp -j DNAT --to-destination 172.20.1.183:80
ipvs模式
ipvs有三种负载均衡模式：
- NAT(k8s用这种模式)
- DR
- TUN
linux内核中的ipvs只有DNAT，没有SNAT; ipvs会使用iptables进行包过滤、SNAT、MASQUERADE。 具体来说，ipvs使用ipset来存储需要NAT或masquared时的ip和端口列表。ipset是iptables的扩展， 允许你创建匹配整个地址sets（地址集合)的规则。而不像普通的iptables链是线性的存储和过滤， ip集合存储在带索引的数据结构中,这种集合比较大也可以进行高效的查找。
SNAT vs MASQUERADE区别：MASQUERADE不需要指定SNAT的目标ip，自动获取
ipvs工作流程图
启用ipvs模式
# yum install -y ipset ipvsadm
# cat << 'EOF' > ipvs.modules
#!/bin/bash
ipvs_modules=(ip_vs ip_vs_lc ip_vs_wlc ip_vs_rr ip_vs_wrr ip_vs_lblc ip_vs_lblcr ip_vs_dh ip_vs_sh ip_vs_fo ip_vs_nq ip_vs_sed ip_vs_ftp nf_conntrack_ipv4)
for kernel_module in ${ipvs_modules[*]}; do
/sbin/modinfo -F filename ${kernel_module} > /dev/null 2>&1
if [ $? -eq 0 ]; then
/sbin/modprobe ${kernel_module}
fi
done
EOF
# bash ipvs.modules
# cut -f1 -d " " /proc/modules | grep -E "ip_vs|nf_conntrack_ipv4"
# kubectl -n kube-system edit cm kube-proxy
mode: "ipvs"
# kubectl -n kube-system get pod -l k8s-app=kube-proxy | grep -v 'NAME' | awk '{print $1}' | xargs kubectl -n kube-system delete pod
# iptables -t filter -F; iptables -t filter -X; iptables -t nat -F; iptables -t nat -X;
kube-proxy ipvs模式使用了nat表和filter表，也定义自定义链
filter表：
- KUBE-FIREWALL
- KUBE-FORWARD
nat表：
- KUBE-FIREWALL
- KUBE-HOSTPORTS
- KUBE-LOAD-BALANCER
- KUBE-MARK-DROP
- KUBE-MARK-MASQ
- KUBE-NODE-PORT
- KUBE-POSTROUTING
- KUBE-SERVICES
ipvs模式下的clusterIP，是可以ping通的，它在宿主机上是真实存在的ip; 因为ipvs的DNAT用到的netfilter hook函数是 作用在INPUT链上，clusterIP会绑定在本机dummy网卡，默认名为kube-ipvs0，内核网络栈识别 到这是本机的IP，从而进入INPUT链；发送的包时候再从POSTROUTING出.
还是以上面httpbin的例子
# kubectl get svc httpbin
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
httpbin ClusterIP 172.20.255.90 <none> 80/TCP 9d
httpbin clusterIP为172.20.255.90(3副本)
clusterIP service类型
访问clusterIP iptables规则链顺序为: (结合上面ipvs工作流程图)
PREROUTING -> KUBE-SERVICES -> KUBE-CLUSTER-IP(ipset) -> INPUT -> KUBE-FIREWALL -> POSTROUTING
1. 进入PREROUTING链
-A PREROUTING -m comment --comment "kubernetes service portals" -j KUBE-SERVICES
2. 跳转至KUBE-SERVICES
-A KUBE-SERVICES -m comment --comment "Kubernetes service cluster ip + port for masquerade purpose" -m set --match-set KUBE-CLUSTER-IP src,dst -j KUBE-MARK-MASQ
3. 进入KUBE-CLUSTER-IP ipset
[root@ice ~]# ipset list |grep -A 30 KUBE-CLUSTER-IP
Name: KUBE-CLUSTER-IP
Type: hash:ip,port
Revision: 2
Header: family inet hashsize 1024 maxelem 65536
Size in memory: 17392
References: 2
Members:
172.20.255.218,tcp:8001
172.20.253.100,tcp:8080
172.20.254.248,tcp:25672
172.20.255.183,tcp:443
172.20.254.248,tcp:15672
172.20.252.10,udp:53
172.20.253.103,tcp:8080
172.20.253.243,tcp:44134
172.20.254.248,tcp:5672
172.20.253.137,tcp:9100
172.20.252.136,tcp:9090
172.20.255.125,tcp:80
172.20.254.248,tcp:4369
172.20.255.100,tcp:80
172.20.252.130,tcp:56790
172.20.255.183,tcp:80
172.20.253.196,tcp:5432
172.20.252.130,tcp:80
172.20.255.57,tcp:443
172.20.253.20,tcp:80
172.20.252.130,tcp:443
172.20.252.10,tcp:53
172.20.254.170,tcp:8080
172.20.255.90,tcp:80 # httpbin clusterIP
4. 再跳转至KUBE-MARK-MASQ，打上标记
-A KUBE-MARK-MASQ -j MARK --set-xmark 0x4000/0x4000
5. 又进入KUBE-CLUSTER-IP ipset, 进行DNAT
-A KUBE-SERVICES -m set --match-set KUBE-CLUSTER-IP dst,dst -j ACCEPT
6. 查看ipvs规则，clusterIP真正存在于宿主机的kube-ipvs0网卡上
# ipvsadm -L -n |grep -A 3 172.20.255.90
TCP 172.20.255.90:80 rr
-> 172.20.0.40:80 Masq 1 0 0
-> 172.20.0.41:80 Masq 1 0 0
-> 172.20.1.183:80 Masq 1 0 0
# ip a show kube-ipvs0 |grep -A 2 172.20.255.90
inet 172.20.255.90/32 brd 172.20.255.90 scope global kube-ipvs0
valid_lft forever preferred_lft forever
7. 进入INPUT链
-A INPUT -j KUBE-FIREWALL
8. 跳转至KUBE-FIREWALL，有0x8000标记，即丢弃
-A KUBE-FIREWALL -m comment --comment "kubernetes firewall for dropping marked packets" -m mark --mark 0x8000/0x8000 -j DROP
9. 进入INPUT链后，ipvs的ip_vs_in hook函数根据ipvs规则直接转发至POSTROUTING链
-A POSTROUTING -m comment --comment "kubernetes postrouting rules" -j KUBE-POSTROUTING
10. 标记0x4000的包，正常MASQUERADE(类SNAT)
-A KUBE-POSTROUTING -m comment --comment "kubernetes service traffic requiring SNAT" -m mark --mark 0x4000/0x4000 -j MASQUERADE
nodePort service类型
非本地访问nodePort的iptables规则链顺序为:
PREROUTING -> KUBE-SERVICES -> KUBE-NODE-PORT -> INPUT --> KUBE-FIREWALL --> POSTROUTING
本地访问nodePort的iptables规则链顺序为:
OUTPUT -> KUBE-SERVICES -> KUBE-NODE-PORT -> INPUT --> KUBE-FIREWALL --> POSTROUTING
分析过程与上述类似.
kube-proxy代码
启动函数
k8s.io/kubernetes/cmd/kube-proxy/proxy.go
func main() {
rand.Seed(time.Now().UnixNano())
command := app.NewProxyCommand()
// TODO: once we switch everything over to Cobra commands, we can go back to calling
// utilflag.InitFlags() (by removing its pflag.Parse() call). For now, we have to set the
// normalize func and add the go flag set by hand.
pflag.CommandLine.SetNormalizeFunc(cliflag.WordSepNormalizeFunc)
pflag.CommandLine.AddGoFlagSet(goflag.CommandLine)
// utilflag.InitFlags()
logs.InitLogs()
defer logs.FlushLogs()
if err := command.Execute(); err != nil {
fmt.Fprintf(os.Stderr, "error: %v\n", err)
os.Exit(1)
}
}
进入到Run函数
k8s.io/kubernetes/cmd/kube-proxy/app/server.go
func (o *Options) Run() error {
defer close(o.errCh)
// 配置写到文件
if len(o.WriteConfigTo) > 0 {
return o.writeConfigFile()
}
// 初始化proxyServer对象
proxyServer, err := NewProxyServer(o)
if err != nil {
return err
}
// 如果为true，执行
if o.CleanupAndExit {
return proxyServer.CleanupAndExit()
}
o.proxyServer = proxyServer
return o.runLoop()
}
NewProxyServer函数 - 初始化proxyServer对象
func newProxyServer(
config *proxyconfigapi.KubeProxyConfiguration,
cleanupAndExit bool,
scheme *runtime.Scheme,
master string) (*ProxyServer, error) {
// config必须有值
if config == nil {
return nil, errors.New("config is required")
}
// 初始化configz.Config对象
if c, err := configz.New(proxyconfigapi.GroupName); err == nil {
c.Set(config)
} else {
return nil, fmt.Errorf("unable to register configz: %s", err)
}
// 支持ipv4,ipv6
protocol := utiliptables.ProtocolIpv4
if net.ParseIP(config.BindAddress).To4() == nil {
klog.V(0).Infof("IPv6 bind address (%s), assume IPv6 operation", config.BindAddress)
protocol = utiliptables.ProtocolIpv6
}
// 初始化变量
var iptInterface utiliptables.Interface
var ipvsInterface utilipvs.Interface
var kernelHandler ipvs.KernelHandler
var ipsetInterface utilipset.Interface
var dbus utildbus.Interface
// 封装了os/exec
// Create a iptables utils.
execer := exec.New()
// 封装了github.com/godbus/dbus，一个与D-Bus交互的golang库
dbus = utildbus.New()
// 初始化操作iptables的对象，针对iptables版本做了check
iptInterface = utiliptables.New(execer, dbus, protocol)
// 初始化操作ipvs模块的对象
kernelHandler = ipvs.NewLinuxKernelHandler()
// 初始化操作ipset的对象
ipsetInterface = utilipset.New(execer)
// 检查ipvs，ipset版本；会尝试在kube-proxy容器里自动加载ipvs所需模块
canUseIPVS, _ := ipvs.CanUseIPVSProxier(kernelHandler, ipsetInterface)
if canUseIPVS {
// 初始化操作ipvs的对象
ipvsInterface = utilipvs.New(execer)
}
// We omit creation of pretty much everything if we run in cleanup mode
if cleanupAndExit {
return &ProxyServer{
execer: execer,
IptInterface: iptInterface,
IpvsInterface: ipvsInterface,
IpsetInterface: ipsetInterface,
}, nil
}
// 初始化clientset
client, eventClient, err := createClients(config.ClientConnection, master)
if err != nil {
return nil, err
}
// Create event recorder
hostname, err := utilnode.GetHostname(config.HostnameOverride)
if err != nil {
return nil, err
}
eventBroadcaster := record.NewBroadcaster()
recorder := eventBroadcaster.NewRecorder(scheme, v1.EventSource{Component: "kube-proxy", Host: hostname})
nodeRef := &v1.ObjectReference{
Kind: "Node",
Name: hostname,
UID: types.UID(hostname),
Namespace: "",
}
var healthzServer *healthcheck.HealthzServer
var healthzUpdater healthcheck.HealthzUpdater
if len(config.HealthzBindAddress) > 0 {
healthzServer = healthcheck.NewDefaultHealthzServer(config.HealthzBindAddress, 2*config.IPTables.SyncPeriod.Duration, recorder, nodeRef)
healthzUpdater = healthzServer
}
var proxier proxy.ProxyProvider
var serviceEventHandler proxyconfig.ServiceHandler
var endpointsEventHandler proxyconfig.EndpointsHandler
// 获取kube-proxy模式，不指定的走iptables模式；检测该模式前置条件失败的话会尝试下一个模式
// 顺序依次为ipvs -> iptables -> usernamespace
proxyMode := getProxyMode(string(config.Mode), iptInterface, kernelHandler, ipsetInterface, iptables.LinuxKernelCompatTester{})
nodeIP := net.ParseIP(config.BindAddress)
if nodeIP.IsUnspecified() {
nodeIP = utilnode.GetNodeIP(client, hostname)
}
if proxyMode == proxyModeIPTables {
klog.V(0).Info("Using iptables Proxier.")
if config.IPTables.MasqueradeBit == nil {
// MasqueradeBit must be specified or defaulted.
return nil, fmt.Errorf("unable to read IPTables MasqueradeBit from config")
}
// 初始化iptables proxier对象
// TODO this has side effects that should only happen when Run() is invoked.
proxierIPTables, err := iptables.NewProxier(
iptInterface,
utilsysctl.New(),
execer,
config.IPTables.SyncPeriod.Duration,
config.IPTables.MinSyncPeriod.Duration,
config.IPTables.MasqueradeAll,
int(*config.IPTables.MasqueradeBit),
config.ClusterCIDR,
hostname,
nodeIP,
recorder,
healthzUpdater,
config.NodePortAddresses,
)
if err != nil {
return nil, fmt.Errorf("unable to create proxier: %v", err)
}
metrics.RegisterMetrics()
proxier = proxierIPTables
serviceEventHandler = proxierIPTables
endpointsEventHandler = proxierIPTables
} else if proxyMode == proxyModeIPVS {
klog.V(0).Info("Using ipvs Proxier.")
// 初始化ipvs proxier对象
proxierIPVS, err := ipvs.NewProxier(
iptInterface,
ipvsInterface,
ipsetInterface,
utilsysctl.New(),
execer,
config.IPVS.SyncPeriod.Duration,
config.IPVS.MinSyncPeriod.Duration,
config.IPVS.ExcludeCIDRs,
config.IPVS.StrictARP,
config.IPTables.MasqueradeAll,
int(*config.IPTables.MasqueradeBit),
config.ClusterCIDR,
hostname,
nodeIP,
recorder,
healthzServer,
config.IPVS.Scheduler,
config.NodePortAddresses,
)
if err != nil {
return nil, fmt.Errorf("unable to create proxier: %v", err)
}
metrics.RegisterMetrics()
proxier = proxierIPVS
serviceEventHandler = proxierIPVS
endpointsEventHandler = proxierIPVS
} else {
klog.V(0).Info("Using userspace Proxier.")
// This is a proxy.LoadBalancer which NewProxier needs but has methods we don't need for
// our config.EndpointsConfigHandler.
loadBalancer := userspace.NewLoadBalancerRR()
// set EndpointsConfigHandler to our loadBalancer
endpointsEventHandler = loadBalancer
// TODO this has side effects that should only happen when Run() is invoked.
proxierUserspace, err := userspace.NewProxier(
loadBalancer,
net.ParseIP(config.BindAddress),
iptInterface,
execer,
*utilnet.ParsePortRangeOrDie(config.PortRange),
config.IPTables.SyncPeriod.Duration,
config.IPTables.MinSyncPeriod.Duration,
config.UDPIdleTimeout.Duration,
config.NodePortAddresses,
)
if err != nil {
return nil, fmt.Errorf("unable to create proxier: %v", err)
}
serviceEventHandler = proxierUserspace
proxier = proxierUserspace
}
iptInterface.AddReloadFunc(proxier.Sync)
return &ProxyServer{
Client: client,
EventClient: eventClient,
IptInterface: iptInterface,
IpvsInterface: ipvsInterface,
IpsetInterface: ipsetInterface,
execer: execer,
Proxier: proxier,
Broadcaster: eventBroadcaster,
Recorder: recorder,
ConntrackConfiguration: config.Conntrack,
Conntracker: &realConntracker{},
ProxyMode: proxyMode,
NodeRef: nodeRef,
MetricsBindAddress: config.MetricsBindAddress,
EnableProfiling: config.EnableProfiling,
OOMScoreAdj: config.OOMScoreAdj,
ResourceContainer: config.ResourceContainer,
ConfigSyncPeriod: config.ConfigSyncPeriod.Duration,
ServiceEventHandler: serviceEventHandler,
EndpointsEventHandler: endpointsEventHandler,
HealthzServer: healthzServer,
}, nil
}
接下来的调用流程：
graph TD
A[o.runLoop] -->B(o.proxyServer.Run)
B --> C(s.Proxier.SyncLoop)
C --> D(proxier.syncRunner.Loop)
D --> E(bfr.tryRun/bfr.fn)
E --> F{模式mode}
F -->|mode=iptables| G[proxier.syncProxyRules]
F -->|mode=ipvs| H[proxier.syncProxyRules]
F -->|mode=usernamespace| I[proxier.syncProxyRules]
Z[调用流程]
最终会根据不同模式，调用到proxier.syncProxyRules；创建相应的iptables规则、ipvs规则，都是具体的命令；这个函数也比较长，可以一条一条规则对着分析.
参考链接
- iptables vs ipvs
- http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.filter_rules.html
- https://blog.tianfeiyu.com/source-code-reading-notes/kubernetes/kube_proxy_ipvs.html
- https://zhuanlan.zhihu.com/p/37230013
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