kube-proxy ＆ Service ＆ Endpoint

kube-proxy & Service & Endpoint

kube-proxy It also runs on every node . It is the realization of Kubernetes Service Important components of the mechanism . No one's surprise ,kube-proxy Also a “ controller ”. It also comes from API Server monitor Service and Endpoint object The change of , And according to Endpoint Object information settings Service To the back end Pod The routing , Maintain network rules , perform TCP、UDP and SCTP Stream forwarding .

Pictured Shown , label app=example Of Pod This is all about it Service Backend Pod, their Pod IP Will be Endpoint The controller is updated to in real time Endpoint In the object . this Serivce Assigned ClusterIP by 192.168.232.109,nodePort by 30004.Pod Of 8080 Port maps to Service Of 80 port . in other words , Within the cluster through 192.168.232.109:80 To access this Service Backend Pod 8080 Port services ; Hosts outside the cluster can use nodeIP:30004 Come and ask Service.

give an example

kd get svc,ep,pod --show-labels -owide

Kubernetes Dashboard

Traffic forwarding

kube-proxy There are two traffic forwarding modes , Namely iptables Patterns and IPVS（IP Virtual Server） Pattern （ You can use the parameter –proxy-mode To specify the ）. The default is iptables Pattern , This mode is implemented through the on each node iptables Rules to achieve .

iptables -t nat -S

With Service An increase in quantity ,iptables Pattern matching due to linear search 、 Full update and so on , Its performance will decrease significantly . from Kubernetes Of 1.8 Version start ,kube-proxy Introduced IPVS Pattern ,IPVS And iptables Also based on netfilter, But it uses a hash table and runs in kernel mode , When Service When the quantity reaches a certain scale , The query speed advantage of hash table will appear , So as to improve Service Service performance .

ipvsadm --list 

Flannel,Calico and Cilium excellent vacancy

Cilium
Flannel,Calico and Cilium excellent vacancy