WEBVTT 00:04.200 --> 00:07.050 Hello and welcome to this lecture. In this lecture 00:07.050 --> 00:13.810 we will discuss about designing a kubernetes cluster. Before you head into designing a cluster. 00:13.820 --> 00:16.490 I must ask the following questions. 00:16.490 --> 00:18.740 What is the purpose of this cluster? 00:18.770 --> 00:25.100 Is it for learning or development or testing purpose or for hosting production grade applications. 00:25.100 --> 00:27.740 What is the cloud adoption at your organization? 00:27.740 --> 00:33.650 Do you prefer your platform to be managed by a cloud provider or a self hosted? 00:33.650 --> 00:37.100 What kind of workloads are you going to run on this cluster? 00:37.100 --> 00:40.400 How many applications are to be hosted on the Cluster? 00:40.490 --> 00:42.050 Few or many? 00:42.050 --> 00:48.590 What kind of applications are going to be hosted on the Cluster? Web applications or big data or analytics? 00:49.310 --> 00:53.880 Depending on the kind of application the resource requirements may vary. 00:53.900 --> 00:57.500 What type of network traffic are these applications expecting? 00:57.500 --> 01:00.900 Continuous heavy traffic or burst? 01:00.910 --> 01:03.510 Well let's try and break down some of these. 01:03.890 --> 01:09.320 If you want to deploy a cluster for learning purposes then a solution based on minikube or a single 01:09.320 --> 01:17.120 node cluster deployed using kubeadm on local VMs or cloud providers like GCP or AWS should do. 01:17.120 --> 01:22.550 We have deployed such a cluster in the beginners course. To deploy a cluster for development and testing 01:22.550 --> 01:28.310 purposes, and multi node cluster with single master and multiple worker nodes would help. 01:28.310 --> 01:34.580 Again kubeadm is an appropriate tool. Or if on managed cloud environments, then quickly provision a 01:34.580 --> 01:44.630 cluster on GCP, AWS or AKS on Azure. Let’s talk about 01:44.660 --> 01:49.020 production level clusters. For hosting production grade applications. 01:49.070 --> 01:54.540 a High Availability Multi node cluster with multiple master nodes is recommended. 01:54.860 --> 02:01.370 We look at more details about High Availability setup with multiple-master nodes later in this section. 02:01.370 --> 02:08.570 Again this can be setup with kubeadm or GCP or using kops on AWS or other supported platforms. 02:08.810 --> 02:15.270 You can have upto 5000 nodes in the cluster, a total of 150k PODs in the cluster, 02:15.300 --> 02:21.770 300,000 containers in total and upto 100 PODs per node. Depending on the size of your 02:21.770 --> 02:22.430 cluster. 02:22.430 --> 02:28.850 the resource requirement for your nodes varies. CSPs like GCP and AWS automatically 02:28.850 --> 02:34.100 selects the right sized nodes for you based on the number of nodes in the cluster. 02:34.100 --> 02:39.680 This table shows the size of the instances and their resource specifications for a specific number of 02:39.680 --> 02:40.100 nodes. 02:40.730 --> 02:47.420 If you are deploying on prem nodes then you could probably start with these numbers as base. Cloud or 02:47.420 --> 02:48.080 Onprem? 02:48.140 --> 02:53.840 We have already discussed that all of these deployment options are available in any environment. For 02:53.840 --> 02:54.830 on-prem 02:54.830 --> 02:57.120 kubeadm is a very useful tool. 02:57.200 --> 03:02.780 Google Container engine makes provisioning kubernetes clusters on GCP very easy. 03:02.780 --> 03:08.990 It comes with one-click cluster upgrade features that makes it very easy to maintain the cluster. KOPS 03:09.050 --> 03:15.890 is a nice tool to deploy kubernetes cluster on AWS and the Azure Kubernetes Service or AKS 03:15.980 --> 03:23.400 helps in managing the hosted kubernetes environment on Azure. Depending on the workloads configured, your 03:23.400 --> 03:30.600 node and disk configurations will differ. For High Performance workloads rely on SSD Backed Storage. For 03:30.600 --> 03:32.680 multiple concurrent access 03:32.730 --> 03:38.410 consider network based storage. For shared access to volumes across multiple PODs, 03:38.490 --> 03:42.910 Consider persistent storage volumes that we discussed in the storage section. 03:43.050 --> 03:49.230 Consider defining different classes of storage and allocating the right class to the right applications. 03:49.320 --> 03:53.410 The Nodes forming a kubernetes cluster can be physical or virtual 03:53.460 --> 03:59.740 In our case we will be deploying virtual machines on VirtualBox environments has nodes of our cluster. 03:59.850 --> 04:05.100 You may chose to deploy on physical machines or virtual machines or cloud environments like GCP, 04:05.260 --> 04:09.140 AWS, Azure or any other platform of your choice. 04:09.180 --> 04:14.550 We will be building a cluster with three nodes one master and two worker nodes. 04:14.550 --> 04:19.860 Now We know that master nodes are for hosting control plane components like the kube-api server, etcd 04:19.860 --> 04:24.030 server and others, while worker nodes for hosting workloads. 04:24.030 --> 04:26.830 However this is not a strict requirement. 04:26.850 --> 04:32.580 The master nodes are also considered as nodes and can host workloads. As a best practice 04:32.580 --> 04:38.370 it is recommended to dedicate master nodes for control plane components only specially in a production 04:38.370 --> 04:39.660 environment. 04:39.660 --> 04:46.350 Deployment tools like kubeadm prevent workloads from being hosted on master nodes by adding a taint to 04:46.350 --> 04:47.850 the master node. 04:48.010 --> 04:52.160 You must use 64 bit Linux operating system for nodes. 04:52.240 --> 04:57.200 Another thing to note is that typically you have all the control plane components on the master nodes. 04:57.370 --> 05:03.460 However, in large clusters you may chose to separate the ETCD clusters from the master node to its 05:03.550 --> 05:05.380 own cluster nodes. 05:05.410 --> 05:09.100 We will discuss more about the different topologies for that in the upcoming lecture 05:09.130 --> 05:14.080 when we talk about high availability setup. Well those are some of the considerations for designing a 05:14.080 --> 05:15.360 kubernetes cluster. 05:15.370 --> 05:20.490 Refer to the links in the references section for more details and some interesting reads. 05:20.560 --> 05:22.040 Well that's it for this lecture. 05:22.180 --> 05:28.420 Before you go from our certification exam standpoint there's really nothing much you need to remember 05:28.420 --> 05:29.200 from this section. 05:29.200 --> 05:34.540 You don't have to memorize the numbers that we discussed as these are available in the documentation 05:34.540 --> 05:41.660 page well we'll get into more interesting topics in the upcoming lectures in this section where we will 05:41.660 --> 05:46.530 provision an actual cluster from scratch by ourselves. 05:46.940 --> 05:48.820 Well that's it for this lecture. 05:48.860 --> 05:50.000 I'll see you in the next election.