1 00:00:01,150 --> 00:00:03,490 Hello and welcome to this lecture. In this lecture 2 00:00:03,490 --> 00:00:09,430 We look at the networking configurations required on the master and worker nodes in a kubernetes cluster. 3 00:00:09,730 --> 00:00:15,610 The kubernetes cluster consists of master and worker nodes. Each node must have at least 1 interface 4 00:00:15,670 --> 00:00:17,170 connected to a network. 5 00:00:17,170 --> 00:00:19,750 Each interface must have an address configured. 6 00:00:19,750 --> 00:00:24,620 The hosts must have a unique hostname set. As well as a unique MAC address. 7 00:00:24,640 --> 00:00:29,750 You should note this especially if you created the VMs by cloning from existing ones. 8 00:00:29,830 --> 00:00:32,740 There are some ports that needs to be opened as well. 9 00:00:32,770 --> 00:00:35,550 These are used by the various components in the control plane. 10 00:00:35,590 --> 00:00:39,980 The master should accept connections on 6443 for the API server. 11 00:00:40,030 --> 00:00:45,850 The worker nodes, Kubectl tool, external users, and all other control plane components access the 12 00:00:45,850 --> 00:00:50,500 kube-api server via this port. The kubelets on the master and worker nodes listen on 13 00:00:50,500 --> 00:00:52,170 10250. Yes, 14 00:00:52,300 --> 00:00:57,050 in case we didn’t discuss this, the kubelet’s can be present on the master node as well. 15 00:00:57,070 --> 00:01:03,220 The kube-scheduler requires port 10251 to be open. The kube-controller-manager requires port 16 00:01:03,220 --> 00:01:10,180 10252 to be open. The worker nodes expose services for external access on ports 30000 to 17 00:01:10,180 --> 00:01:11,860 32767. 18 00:01:11,950 --> 00:01:13,270 So these should be open as well. 19 00:01:13,330 --> 00:01:17,260 Finally, the ETCD server listens on port 2379. 20 00:01:17,320 --> 00:01:23,020 If you have multiple master nodes, all of these ports need to be open on those as well. And you also need 21 00:01:23,020 --> 00:01:28,240 an additional port 2380 open so the ETCD clients can communicate with each other. 22 00:01:28,270 --> 00:01:33,430 The list of ports to be opened are also available in the kubernetes documentation page. 23 00:01:33,430 --> 00:01:39,430 So consider these when you setup networking for your nodes, in your firewalls, or ip table rules or network 24 00:01:39,430 --> 00:01:45,370 security group in a cloud environment such as GCP or Azure or AWS. And if things are not working 25 00:01:45,430 --> 00:01:50,530 this is one place to look for while you are investigating. Head over to the practice session and explore 26 00:01:50,530 --> 00:01:53,140 the networking setup in the existing environment. 27 00:01:53,140 --> 00:01:56,020 Keep this commands handy while you look for information. 28 00:01:56,050 --> 00:02:01,000 We will start with simple exercises where you will explore an existing kubernetes cluster and view 29 00:02:01,000 --> 00:02:05,040 information about the interfaces, ips, hostnames, ports etc. 30 00:02:05,050 --> 00:02:09,540 This will help you familiarize with the environment and look for information in the future sections. 31 00:02:09,550 --> 00:02:12,580 Going forward we will get into more challenging exercises. 32 00:02:12,640 --> 00:02:14,200 For now let's start slow.