1 00:00:00,980 --> 00:00:08,170 Hello and welcome to this lecture. In this lecture, we will talk about Kube Proxy. Within a kubernetes 2 00:00:08,170 --> 00:00:12,210 cluster every pod can reach every other pod. 3 00:00:12,220 --> 00:00:19,150 This is accomplished by deploying a POD networking solution to the cluster. A POD network is an internal 4 00:00:19,150 --> 00:00:25,810 virtual network that spans across all the nodes in the cluster to which all the PODs connect to. Through this 5 00:00:25,810 --> 00:00:29,200 network are able to communicate with each other. 6 00:00:29,200 --> 00:00:32,830 There are many solutions available for deploying such a network. 7 00:00:32,830 --> 00:00:38,770 In this case I have a web application deployed on the first node and a database application deployed 8 00:00:38,770 --> 00:00:39,890 on the second. 9 00:00:40,220 --> 00:00:45,320 The web app can reach the database, simply by using the IP of the database POD. 10 00:00:45,340 --> 00:00:50,520 But there is no guarantee that the IP of the database part will always remain the same. 11 00:00:50,560 --> 00:00:56,140 If you've gone through the lecture on services as discussed in the beginners course you must know that 12 00:00:56,200 --> 00:01:02,470 a better way for the web application to access the database is using a service. So we create a service 13 00:01:02,500 --> 00:01:05,670 to expose the database application across the cluster. 14 00:01:06,520 --> 00:01:12,400 The web application can now access the database using the name of the service db. 15 00:01:12,520 --> 00:01:19,670 The service also gets an IP address assigned to it whenever a pod tries to reach the service using its 16 00:01:19,670 --> 00:01:24,340 IP or name it forwards the traffic to the back end pod. 17 00:01:24,350 --> 00:01:26,550 In this case the database. 18 00:01:26,550 --> 00:01:29,890 But what is this service and how does it get an IP? 19 00:01:29,900 --> 00:01:33,210 Does the service join the same POD Network? 20 00:01:33,400 --> 00:01:38,960 The service cannot join the pod network because the service is not an actual thing. 21 00:01:39,090 --> 00:01:45,570 It is not a container like pod so it doesn't have any interfaces or an actively listening process. 22 00:01:45,570 --> 00:01:49,850 It is a virtual component that only lives in the cabinet as memory. 23 00:01:50,430 --> 00:01:55,470 But then we also said that the service should be accessible across the cluster from any not. 24 00:01:55,830 --> 00:01:57,670 So how is that achieved? 25 00:01:57,690 --> 00:02:00,140 That’s where kube-proxy comes in. 26 00:02:00,240 --> 00:02:06,380 Kube-proxy is a process that runs on each node in the kubernetes cluster. 27 00:02:06,390 --> 00:02:14,040 Its job is to look for new services and every time a new service is created it creates the appropriate 28 00:02:14,100 --> 00:02:20,490 rules on each node to forward traffic to those services to the backend pods. 29 00:02:20,490 --> 00:02:24,170 One way it does this is using IPTABLES rules. 30 00:02:24,300 --> 00:02:31,080 In this case it creates an IP tables rule on each node in the cluster to forward traffic heading to 31 00:02:31,080 --> 00:02:38,540 the IP of the service which is 10.96.0.12 to the IP of the actual pod which is 32 00:02:38,550 --> 00:02:44,220 10.32.0.15. So how kube-proxy configure the service 33 00:02:44,220 --> 00:02:50,180 We discuss a lot more about networking and services kube-proxy and POD networking. 34 00:02:50,220 --> 00:02:55,930 Later in this course again we have a large section just for networking. 35 00:02:56,010 --> 00:02:59,000 This is a high level overview for now. 36 00:02:59,280 --> 00:03:02,400 We will now see how to install kube-proxy. 37 00:03:02,400 --> 00:03:09,140 Download the kube-proxy binary from the kubernetes release page. Extract it and run it as a service. The 38 00:03:09,140 --> 00:03:12,980 kubeadm tool deploys kube-proxy as PODs on each node. 39 00:03:12,980 --> 00:03:20,210 In fact it is deployed as a daemon set, so a single POD is always deployed on each node in the cluster. 40 00:03:20,210 --> 00:03:25,010 Well if you don't know about daemon set yet don't worry we have a lecture on that coming up in this 41 00:03:25,010 --> 00:03:26,460 course. 42 00:03:26,510 --> 00:03:31,640 We have now covered a high-level overview of the various components in the kubernetes control plane. 43 00:03:31,640 --> 00:03:37,580 As mentioned we will look at some of these in much more detail at various sections in this course. 44 00:03:37,580 --> 00:03:39,210 Well that's it for this lecture. 45 00:03:39,620 --> 00:03:41,300 I will see you in the next section.