1 00:00:00,180 --> 00:00:03,370 Hello and welcome to this lecture in this lecture. 2 00:00:03,390 --> 00:00:09,870 We will discuss about namespaces in kubernetes, let us begin with an analogy. 3 00:00:09,920 --> 00:00:15,460 There are two boys named Mark to differentiate them from each other. 4 00:00:15,530 --> 00:00:17,580 We call them by their last names. 5 00:00:17,840 --> 00:00:21,760 Smith and Williams they come from different houses. 6 00:00:21,860 --> 00:00:28,320 Of course the Smiths and the Williams There are other members in the house. 7 00:00:28,320 --> 00:00:33,810 The individuals within the house address each other simply by their first names. 8 00:00:33,870 --> 00:00:38,740 For example the father addresses Mark simply as Mark. 9 00:00:38,910 --> 00:00:47,180 However if the father wishes to address the mark in the other house he would use the full name someone 10 00:00:47,180 --> 00:00:54,190 outside of these houses would also use the full name to refer to the boys or anyone within these houses. 11 00:00:55,910 --> 00:01:03,150 Each of these houses have their own set of rules that defines who does what each of these houses have 12 00:01:03,150 --> 00:01:08,280 their own set of resources that they can consume. 13 00:01:08,290 --> 00:01:16,200 Now let's get back to kubernetes these houses correspond to namespaces in kubernetes. 14 00:01:16,560 --> 00:01:23,000 So far in this course we've created objects such as pods deployments and services in our cluster. 15 00:01:23,430 --> 00:01:28,890 Whatever we have been doing we have been doing within a namespace. 16 00:01:28,950 --> 00:01:37,620 We were inside a house all this while this namespace is known as the default namespace and it is created 17 00:01:37,740 --> 00:01:45,150 automatically kubernetes, when the cluster is first set up kubernetes, creates a set of pods 18 00:01:45,150 --> 00:01:50,650 and services for its internal purpose such as those required by the networking solution. 19 00:01:50,820 --> 00:01:57,960 The DNS service etc. to isolate these from the user and to prevent you from accidentally deleting or 20 00:01:57,960 --> 00:02:04,890 modifying these services kubernetes creates them under another namespace created at cluster startup 21 00:02:05,310 --> 00:02:13,930 named Kube system a third namespace created by Coburn that is automatically is called kube public. 22 00:02:13,960 --> 00:02:18,450 This is where resources that should be made available to all users are created. 23 00:02:20,130 --> 00:02:25,980 If your environment is small or your learning and playing around with a small cluster you shouldn't 24 00:02:25,980 --> 00:02:31,990 really have to worry about namespaces you could continue to work in the default namespace. 25 00:02:32,070 --> 00:02:38,880 However as and when you grow and use a kubernetes cluster for enterprise or production purposes you 26 00:02:38,880 --> 00:02:46,430 may want to consider the use of namespace as you can create your own namespaces as well. 27 00:02:46,440 --> 00:02:52,890 For example, if you wanted to use the same cluster for both dev and production environment but at the 28 00:02:52,890 --> 00:02:59,860 same time isolate the resources between them you can create a different namespace for each of them. 29 00:02:59,970 --> 00:03:06,390 That way while working in the dev environment you don't accidentally modify a resources in production. 30 00:03:06,390 --> 00:03:12,300 Each of these namespace can have its own set of policies that define who can do what. 31 00:03:12,330 --> 00:03:19,560 You can also assign quota of resources to each of these named spaces that we each namespace is guaranteed 32 00:03:19,650 --> 00:03:22,920 a certain amount and does not use more than it's allowed. 33 00:03:22,920 --> 00:03:29,810 Limit going back to the default namespace that we have been working on just like how the members within 34 00:03:29,810 --> 00:03:32,840 the House refer to each other by their first names. 35 00:03:32,990 --> 00:03:38,190 The resources within a namespace can refer to each other simply by their names. 36 00:03:38,210 --> 00:03:47,630 In this case the web app part can reach the db service simply using the hostname db service if required. 37 00:03:47,710 --> 00:03:52,400 The Web app Pod can reach a service in another namespace as well. 38 00:03:52,420 --> 00:03:56,950 For this you must append the name of the namespace to the name of the service. 39 00:03:57,040 --> 00:04:02,950 For example for the web pod in the default namespace to connect to the database in the dev environment 40 00:04:03,300 --> 00:04:04,570 or namespace. 41 00:04:04,570 --> 00:04:13,320 Use the servicename.namespace.svc.cluste.local format that would be db service. 42 00:04:13,500 --> 00:04:22,260 Dev.SVC.cluster.local you're able to do this because when the service is created a DNS entry 43 00:04:22,290 --> 00:04:29,000 is added automatically in this format looking closely at the DNS name of the service. 44 00:04:29,000 --> 00:04:37,810 The last part Cluster.local is the default domain name of the kubernetes cluster SVC is the subdomain 45 00:04:37,870 --> 00:04:42,490 for service followed by the namespace and then the name of the service itself. 46 00:04:46,190 --> 00:04:50,080 Let us now look at some of the operational aspects of namespace. 47 00:04:50,140 --> 00:04:52,290 Let's start with a Kube control commands. 48 00:04:52,430 --> 00:05:00,020 For example, this command is used to list all the pods but it only lists the pods in the default namespace 49 00:05:00,860 --> 00:05:03,330 to list pods in another namespace. 50 00:05:03,350 --> 00:05:08,000 Use the namespace option in the command along with the name of the namespace. 51 00:05:08,000 --> 00:05:16,830 In this case Kube system here I have a pod definition file when you create a pod using this file. 52 00:05:16,910 --> 00:05:22,400 The pod is created in the default namespace to create a pod in another namespace. 53 00:05:22,400 --> 00:05:30,340 Use the namespace option if you want to make sure that this board gets created in the dev environment 54 00:05:30,400 --> 00:05:31,480 all the time. 55 00:05:31,570 --> 00:05:37,450 Even if you don't specify the namespace in the command line you can move the namespace definition into 56 00:05:37,450 --> 00:05:42,300 the pod definition file like this under the metadata section. 57 00:05:42,310 --> 00:05:48,530 This is a good way to ensure your resources are always created in the same namespace. 58 00:05:48,640 --> 00:05:52,910 So how do you create a new namespace like any other object. 59 00:05:53,020 --> 00:06:01,390 Use an namespace definition file the API version is V1 kind is namespace and under metadata specify 60 00:06:01,390 --> 00:06:02,410 the name. 61 00:06:02,410 --> 00:06:03,100 In this case. 62 00:06:03,100 --> 00:06:07,900 Dev run the Kube control create command to create the namespace. 63 00:06:07,930 --> 00:06:12,790 Another way to create a namespace is by simply running the command Kube control. 64 00:06:12,790 --> 00:06:20,560 Create namespace followed by the name of the namespace now say we're working in three namespaces. 65 00:06:20,770 --> 00:06:27,070 As we discussed before by default we are in the default namespace which is why we can see the resources 66 00:06:27,130 --> 00:06:34,240 inside the default namespace using the kube control get pods command and to view those in the dev namespace. 67 00:06:34,240 --> 00:06:41,410 We have to use the namespace option but what if we want to switch to the dev namespace permanently so 68 00:06:41,410 --> 00:06:45,320 that we don't have to specify the namespace option anymore. 69 00:06:45,340 --> 00:06:52,210 Well, in that case, use the Kube control config command to set the namespace in the current context. 70 00:06:52,210 --> 00:06:59,810 Dev you can then simply run the Kube control get pods command without the namespace option to list pods 71 00:06:59,900 --> 00:07:06,590 in the dev environment but you will need to specify the option for other environments such as default 72 00:07:06,710 --> 00:07:12,010 or prod similarly you can switch to the prod namespace the same way. 73 00:07:13,310 --> 00:07:20,390 Finally to view pods in all namespace use the all namespace option in the command. 74 00:07:20,390 --> 00:07:26,320 This will list all the pods in all of the namespace is taking a closer look at the command. 75 00:07:26,420 --> 00:07:33,740 This command first identifies the current context and then sets the namespace to the desired one for 76 00:07:33,740 --> 00:07:35,840 that current context. 77 00:07:35,840 --> 00:07:41,660 Well contexts are used to manage multiple clusters in multiple environments from the same management 78 00:07:41,660 --> 00:07:42,610 system. 79 00:07:42,740 --> 00:07:49,100 It is a totally separate topic to discuss and requires its own lecture so we will discuss context in 80 00:07:49,100 --> 00:07:52,460 another lecture to limit resources in a namespace. 81 00:07:52,460 --> 00:07:56,490 Create a resource quota to create one. 82 00:07:56,510 --> 00:08:02,570 Start with a definition file for resource quota specify the namespace for which you want to create the 83 00:08:02,570 --> 00:08:10,940 quota and then under spec provide your limits such as 10 pods 10 CPU units 10 GB byte of memory 84 00:08:10,940 --> 00:08:12,260 etc.. 85 00:08:12,410 --> 00:08:14,570 Well that's it for this lecture. 86 00:08:14,570 --> 00:08:20,660 Head over to the coding exercise and section and practice working with namespaces and I will see you 87 00:08:20,870 --> 00:08:21,770 in the next lecture.