WEBVTT 00:01.060 --> 00:03.820 Hello and welcome to this lecture in the previous lecture. 00:03.820 --> 00:06.910 we discussed the basics of ETCD. In this 00:06.910 --> 00:13.330 lecture we will talk about ETCD’s role in kubernetes. The ETCD datastore stores information regarding the 00:13.330 --> 00:20.170 cluster such as the nodes, pods, configs, secrets, accounts, roles, bindings and others. 00:20.350 --> 00:26.800 Every information you see when you run the kubectl get command is from the ETCD server. Every change 00:26.860 --> 00:33.250 you make to your cluster, such as adding additional nodes, deploying pods or replica sets are updated 00:33.340 --> 00:40.300 in the ETCD server. Only once it is updated in the ETCD server, is the change considered to be complete. 00:41.330 --> 00:48.530 Depending on how you setup your cluster, ETCD is deployed differently. Throughout this section we discuss 00:48.530 --> 00:55.550 about two types of kubernetes deployment. One deployed from scratch and other using kubeadm tool. 00:56.310 --> 01:01.490 The practice test environments are deployed using the kubeadm tool and later in this course when 01:01.490 --> 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 01:08.360 --> 01:14.360 if you set up your cluster from scratch then you deploy ETCD by downloading the ETCD binaries yourself, 01:14.810 --> 01:20.900 installing the binaries and configuring ETCD as a service in your master node yourself. There are many 01:20.900 --> 01:27.290 options passed into the service a number of them relate to certificates we will learn more about these 01:27.290 --> 01:33.500 certificates how to create them and how to configure them later in this course we have a whole section 01:33.500 --> 01:40.610 on TLS certificates. The others are about configuring ETCD as a cluster. We will look at those options 01:40.700 --> 01:47.730 when we set up high availability in kubernetes the only option to note for now is the advertised client 01:47.760 --> 01:48.400 url. 01:48.900 --> 01:55.650 This is the address on which ETCD listens. It happens to be on the IP of the server and on port 01:55.650 --> 02:00.390 2379, which is the default port on which etcd listens. 02:00.390 --> 02:06.170 This is the URL that should be configured on the kube-api server when it tries to reach the etcd server. 02:07.140 --> 02:13.770 If you setup your cluster using kubeadm then kubeadm deploys the ETCD server for you as a POD in 02:13.770 --> 02:20.360 the kube-system namespace. You can explore the etcd database using the etcdctl utility within this 02:20.360 --> 02:30.320 pod. To list all keys stored by kubernetes, run the etcdctl get command like this. Kubernetes stores 02:30.330 --> 02:36.750 data in the specific directory structure the root directory is a registry and under that you have the 02:36.750 --> 02:44.380 various kubernetes constructs such as minions or nodes, pods, replicasets, deployments etc. In a 02:44.380 --> 02:49.420 high availability environment you will have multiple master nodes in your cluster then you will have 02:49.420 --> 02:53.030 multiple ETCD instances spread across the master nodes. 02:53.170 --> 02:58.450 In that case, make sure to specify the ETCD instances know about each other by setting the right parameter 02:58.480 --> 03:04.090 in the ETCD service configuration. The initial-cluster option is where you must specify the different 03:04.180 --> 03:06.850 instances of the ETCD service. 03:06.850 --> 03:12.130 We talk about high availability in much more detail later in this course but I thought its worth while 03:12.160 --> 03:14.050 to point it out here. 03:14.050 --> 03:16.900 Well, that's it for this lecture and I will see you in the next.