WEBVTT 00:00.180 --> 00:03.370 Hello and welcome to this lecture in this lecture. 00:03.390 --> 00:09.870 We will discuss about namespaces in kubernetes, let us begin with an analogy. 00:09.920 --> 00:15.460 There are two boys named Mark to differentiate them from each other. 00:15.530 --> 00:17.580 We call them by their last names. 00:17.840 --> 00:21.760 Smith and Williams they come from different houses. 00:21.860 --> 00:28.320 Of course the Smiths and the Williams There are other members in the house. 00:28.320 --> 00:33.810 The individuals within the house address each other simply by their first names. 00:33.870 --> 00:38.740 For example the father addresses Mark simply as Mark. 00:38.910 --> 00:47.180 However if the father wishes to address the mark in the other house he would use the full name someone 00:47.180 --> 00:54.190 outside of these houses would also use the full name to refer to the boys or anyone within these houses. 00:55.910 --> 01:03.150 Each of these houses have their own set of rules that defines who does what each of these houses have 01:03.150 --> 01:08.280 their own set of resources that they can consume. 01:08.290 --> 01:16.200 Now let's get back to kubernetes these houses correspond to namespaces in kubernetes. 01:16.560 --> 01:23.000 So far in this course we've created objects such as pods deployments and services in our cluster. 01:23.430 --> 01:28.890 Whatever we have been doing we have been doing within a namespace. 01:28.950 --> 01:37.620 We were inside a house all this while this namespace is known as the default namespace and it is created 01:37.740 --> 01:45.150 automatically kubernetes, when the cluster is first set up kubernetes, creates a set of pods 01:45.150 --> 01:50.650 and services for its internal purpose such as those required by the networking solution. 01:50.820 --> 01:57.960 The DNS service etc. to isolate these from the user and to prevent you from accidentally deleting or 01:57.960 --> 02:04.890 modifying these services kubernetes creates them under another namespace created at cluster startup 02:05.310 --> 02:13.930 named Kube system a third namespace created by Coburn that is automatically is called kube public. 02:13.960 --> 02:18.450 This is where resources that should be made available to all users are created. 02:20.130 --> 02:25.980 If your environment is small or your learning and playing around with a small cluster you shouldn't 02:25.980 --> 02:31.990 really have to worry about namespaces you could continue to work in the default namespace. 02:32.070 --> 02:38.880 However as and when you grow and use a kubernetes cluster for enterprise or production purposes you 02:38.880 --> 02:46.430 may want to consider the use of namespace as you can create your own namespaces as well. 02:46.440 --> 02:52.890 For example, if you wanted to use the same cluster for both dev and production environment but at the 02:52.890 --> 02:59.860 same time isolate the resources between them you can create a different namespace for each of them. 02:59.970 --> 03:06.390 That way while working in the dev environment you don't accidentally modify a resources in production. 03:06.390 --> 03:12.300 Each of these namespace can have its own set of policies that define who can do what. 03:12.330 --> 03:19.560 You can also assign quota of resources to each of these named spaces that we each namespace is guaranteed 03:19.650 --> 03:22.920 a certain amount and does not use more than it's allowed. 03:22.920 --> 03:29.810 Limit going back to the default namespace that we have been working on just like how the members within 03:29.810 --> 03:32.840 the House refer to each other by their first names. 03:32.990 --> 03:38.190 The resources within a namespace can refer to each other simply by their names. 03:38.210 --> 03:47.630 In this case the web app part can reach the db service simply using the hostname db service if required. 03:47.710 --> 03:52.400 The Web app Pod can reach a service in another namespace as well. 03:52.420 --> 03:56.950 For this you must append the name of the namespace to the name of the service. 03:57.040 --> 04:02.950 For example for the web pod in the default namespace to connect to the database in the dev environment 04:03.300 --> 04:04.570 or namespace. 04:04.570 --> 04:13.320 Use the servicename.namespace.svc.cluste.local format that would be db service. 04:13.500 --> 04:22.260 Dev.SVC.cluster.local you're able to do this because when the service is created a DNS entry 04:22.290 --> 04:29.000 is added automatically in this format looking closely at the DNS name of the service. 04:29.000 --> 04:37.810 The last part Cluster.local is the default domain name of the kubernetes cluster SVC is the subdomain 04:37.870 --> 04:42.490 for service followed by the namespace and then the name of the service itself. 04:46.190 --> 04:50.080 Let us now look at some of the operational aspects of namespace. 04:50.140 --> 04:52.290 Let's start with a Kube control commands. 04:52.430 --> 05:00.020 For example, this command is used to list all the pods but it only lists the pods in the default namespace 05:00.860 --> 05:03.330 to list pods in another namespace. 05:03.350 --> 05:08.000 Use the namespace option in the command along with the name of the namespace. 05:08.000 --> 05:16.830 In this case Kube system here I have a pod definition file when you create a pod using this file. 05:16.910 --> 05:22.400 The pod is created in the default namespace to create a pod in another namespace. 05:22.400 --> 05:30.340 Use the namespace option if you want to make sure that this board gets created in the dev environment 05:30.400 --> 05:31.480 all the time. 05:31.570 --> 05:37.450 Even if you don't specify the namespace in the command line you can move the namespace definition into 05:37.450 --> 05:42.300 the pod definition file like this under the metadata section. 05:42.310 --> 05:48.530 This is a good way to ensure your resources are always created in the same namespace. 05:48.640 --> 05:52.910 So how do you create a new namespace like any other object. 05:53.020 --> 06:01.390 Use an namespace definition file the API version is V1 kind is namespace and under metadata specify 06:01.390 --> 06:02.410 the name. 06:02.410 --> 06:03.100 In this case. 06:03.100 --> 06:07.900 Dev run the Kube control create command to create the namespace. 06:07.930 --> 06:12.790 Another way to create a namespace is by simply running the command Kube control. 06:12.790 --> 06:20.560 Create namespace followed by the name of the namespace now say we're working in three namespaces. 06:20.770 --> 06:27.070 As we discussed before by default we are in the default namespace which is why we can see the resources 06:27.130 --> 06:34.240 inside the default namespace using the kube control get pods command and to view those in the dev namespace. 06:34.240 --> 06:41.410 We have to use the namespace option but what if we want to switch to the dev namespace permanently so 06:41.410 --> 06:45.320 that we don't have to specify the namespace option anymore. 06:45.340 --> 06:52.210 Well, in that case, use the Kube control config command to set the namespace in the current context. 06:52.210 --> 06:59.810 Dev you can then simply run the Kube control get pods command without the namespace option to list pods 06:59.900 --> 07:06.590 in the dev environment but you will need to specify the option for other environments such as default 07:06.710 --> 07:12.010 or prod similarly you can switch to the prod namespace the same way. 07:13.310 --> 07:20.390 Finally to view pods in all namespace use the all namespace option in the command. 07:20.390 --> 07:26.320 This will list all the pods in all of the namespace is taking a closer look at the command. 07:26.420 --> 07:33.740 This command first identifies the current context and then sets the namespace to the desired one for 07:33.740 --> 07:35.840 that current context. 07:35.840 --> 07:41.660 Well contexts are used to manage multiple clusters in multiple environments from the same management 07:41.660 --> 07:42.610 system. 07:42.740 --> 07:49.100 It is a totally separate topic to discuss and requires its own lecture so we will discuss context in 07:49.100 --> 07:52.460 another lecture to limit resources in a namespace. 07:52.460 --> 07:56.490 Create a resource quota to create one. 07:56.510 --> 08:02.570 Start with a definition file for resource quota specify the namespace for which you want to create the 08:02.570 --> 08:10.940 quota and then under spec provide your limits such as 10 pods 10 CPU units 10 GB byte of memory 08:10.940 --> 08:12.260 etc.. 08:12.410 --> 08:14.570 Well that's it for this lecture. 08:14.570 --> 08:20.660 Head over to the coding exercise and section and practice working with namespaces and I will see you 08:20.870 --> 08:21.770 in the next lecture.