1 00:00:01,060 --> 00:00:03,820 Hello and welcome to this lecture in the previous lecture. 2 00:00:03,820 --> 00:00:06,910 we discussed the basics of ETCD. In this 3 00:00:06,910 --> 00:00:13,330 lecture we will talk about ETCD’s role in kubernetes. The ETCD datastore stores information regarding the 4 00:00:13,330 --> 00:00:20,170 cluster such as the nodes, pods, configs, secrets, accounts, roles, bindings and others. 5 00:00:20,350 --> 00:00:26,800 Every information you see when you run the kubectl get command is from the ETCD server. Every change 6 00:00:26,860 --> 00:00:33,250 you make to your cluster, such as adding additional nodes, deploying pods or replica sets are updated 7 00:00:33,340 --> 00:00:40,300 in the ETCD server. Only once it is updated in the ETCD server, is the change considered to be complete. 8 00:00:41,330 --> 00:00:48,530 Depending on how you setup your cluster, ETCD is deployed differently. Throughout this section we discuss 9 00:00:48,530 --> 00:00:55,550 about two types of kubernetes deployment. One deployed from scratch and other using kubeadm tool. 10 00:00:56,310 --> 00:01:01,490 The practice test environments are deployed using the kubeadm tool and later in this course when 11 00:01:01,490 --> 00:01:07,550 we set up a cluster we set it up from scratch so it's good to know the difference between the two methods 12 00:01:08,360 --> 00:01:14,360 if you set up your cluster from scratch then you deploy ETCD by downloading the ETCD binaries yourself, 13 00:01:14,810 --> 00:01:20,900 installing the binaries and configuring ETCD as a service in your master node yourself. There are many 14 00:01:20,900 --> 00:01:27,290 options passed into the service a number of them relate to certificates we will learn more about these 15 00:01:27,290 --> 00:01:33,500 certificates how to create them and how to configure them later in this course we have a whole section 16 00:01:33,500 --> 00:01:40,610 on TLS certificates. The others are about configuring ETCD as a cluster. We will look at those options 17 00:01:40,700 --> 00:01:47,730 when we set up high availability in kubernetes the only option to note for now is the advertised client 18 00:01:47,760 --> 00:01:48,400 url. 19 00:01:48,900 --> 00:01:55,650 This is the address on which ETCD listens. It happens to be on the IP of the server and on port 20 00:01:55,650 --> 00:02:00,390 2379, which is the default port on which etcd listens. 21 00:02:00,390 --> 00:02:06,170 This is the URL that should be configured on the kube-api server when it tries to reach the etcd server. 22 00:02:07,140 --> 00:02:13,770 If you setup your cluster using kubeadm then kubeadm deploys the ETCD server for you as a POD in 23 00:02:13,770 --> 00:02:20,360 the kube-system namespace. You can explore the etcd database using the etcdctl utility within this 24 00:02:20,360 --> 00:02:30,320 pod. To list all keys stored by kubernetes, run the etcdctl get command like this. Kubernetes stores 25 00:02:30,330 --> 00:02:36,750 data in the specific directory structure the root directory is a registry and under that you have the 26 00:02:36,750 --> 00:02:44,380 various kubernetes constructs such as minions or nodes, pods, replicasets, deployments etc. In a 27 00:02:44,380 --> 00:02:49,420 high availability environment you will have multiple master nodes in your cluster then you will have 28 00:02:49,420 --> 00:02:53,030 multiple ETCD instances spread across the master nodes. 29 00:02:53,170 --> 00:02:58,450 In that case, make sure to specify the ETCD instances know about each other by setting the right parameter 30 00:02:58,480 --> 00:03:04,090 in the ETCD service configuration. The initial-cluster option is where you must specify the different 31 00:03:04,180 --> 00:03:06,850 instances of the ETCD service. 32 00:03:06,850 --> 00:03:12,130 We talk about high availability in much more detail later in this course but I thought its worth while 33 00:03:12,160 --> 00:03:14,050 to point it out here. 34 00:03:14,050 --> 00:03:16,900 Well, that's it for this lecture and I will see you in the next.