WEBVTT 00:00.980 --> 00:08.170 Hello and welcome to this lecture. In this lecture, we will talk about Kube Proxy. Within a kubernetes 00:08.170 --> 00:12.210 cluster every pod can reach every other pod. 00:12.220 --> 00:19.150 This is accomplished by deploying a POD networking solution to the cluster. A POD network is an internal 00:19.150 --> 00:25.810 virtual network that spans across all the nodes in the cluster to which all the PODs connect to. Through this 00:25.810 --> 00:29.200 network are able to communicate with each other. 00:29.200 --> 00:32.830 There are many solutions available for deploying such a network. 00:32.830 --> 00:38.770 In this case I have a web application deployed on the first node and a database application deployed 00:38.770 --> 00:39.890 on the second. 00:40.220 --> 00:45.320 The web app can reach the database, simply by using the IP of the database POD. 00:45.340 --> 00:50.520 But there is no guarantee that the IP of the database part will always remain the same. 00:50.560 --> 00:56.140 If you've gone through the lecture on services as discussed in the beginners course you must know that 00:56.200 --> 01:02.470 a better way for the web application to access the database is using a service. So we create a service 01:02.500 --> 01:05.670 to expose the database application across the cluster. 01:06.520 --> 01:12.400 The web application can now access the database using the name of the service db. 01:12.520 --> 01:19.670 The service also gets an IP address assigned to it whenever a pod tries to reach the service using its 01:19.670 --> 01:24.340 IP or name it forwards the traffic to the back end pod. 01:24.350 --> 01:26.550 In this case the database. 01:26.550 --> 01:29.890 But what is this service and how does it get an IP? 01:29.900 --> 01:33.210 Does the service join the same POD Network? 01:33.400 --> 01:38.960 The service cannot join the pod network because the service is not an actual thing. 01:39.090 --> 01:45.570 It is not a container like pod so it doesn't have any interfaces or an actively listening process. 01:45.570 --> 01:49.850 It is a virtual component that only lives in the cabinet as memory. 01:50.430 --> 01:55.470 But then we also said that the service should be accessible across the cluster from any not. 01:55.830 --> 01:57.670 So how is that achieved? 01:57.690 --> 02:00.140 That’s where kube-proxy comes in. 02:00.240 --> 02:06.380 Kube-proxy is a process that runs on each node in the kubernetes cluster. 02:06.390 --> 02:14.040 Its job is to look for new services and every time a new service is created it creates the appropriate 02:14.100 --> 02:20.490 rules on each node to forward traffic to those services to the backend pods. 02:20.490 --> 02:24.170 One way it does this is using IPTABLES rules. 02:24.300 --> 02:31.080 In this case it creates an IP tables rule on each node in the cluster to forward traffic heading to 02:31.080 --> 02:38.540 the IP of the service which is 10.96.0.12 to the IP of the actual pod which is 02:38.550 --> 02:44.220 10.32.0.15. So how kube-proxy configure the service 02:44.220 --> 02:50.180 We discuss a lot more about networking and services kube-proxy and POD networking. 02:50.220 --> 02:55.930 Later in this course again we have a large section just for networking. 02:56.010 --> 02:59.000 This is a high level overview for now. 02:59.280 --> 03:02.400 We will now see how to install kube-proxy. 03:02.400 --> 03:09.140 Download the kube-proxy binary from the kubernetes release page. Extract it and run it as a service. The 03:09.140 --> 03:12.980 kubeadm tool deploys kube-proxy as PODs on each node. 03:12.980 --> 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. 03:20.210 --> 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 03:25.010 --> 03:26.460 course. 03:26.510 --> 03:31.640 We have now covered a high-level overview of the various components in the kubernetes control plane. 03:31.640 --> 03:37.580 As mentioned we will look at some of these in much more detail at various sections in this course. 03:37.580 --> 03:39.210 Well that's it for this lecture. 03:39.620 --> 03:41.300 I will see you in the next section.