WEBVTT 00:00.000 --> 00:04.080 In this demo, we're going to create a pod again 00:04.080 --> 00:08.820 but this time, instead of making use of the kubectl run command, 00:08.820 --> 00:12.460 we're going to create it using a YAML definition file. 00:12.460 --> 00:18.140 Our goal is to create a YAML file with the pod specifications in it. 00:18.140 --> 00:20.620 Now, there are many ways to do it. 00:20.620 --> 00:24.820 You could just create one in any text editor. 00:25.010 --> 00:27.720 If you're on windows, you could just use Notepad. 00:27.720 --> 00:33.200 If you're on Linux as I am, just use a native editor like Vi or Vim. 00:33.200 --> 00:35.880 An editor with support for YAML language 00:35.880 --> 00:40.480 would be very helpful in getting the syntax right. 00:40.480 --> 00:45.330 Instead of Notepad, a tool like Notepad++ in Windows 00:45.330 --> 00:48.560 or Vim in Linux would be better. 00:48.560 --> 00:52.740 Now, I'll talk more about tips and tricks and other tools and ideas 00:52.740 --> 00:57.890 that can help with this more in the upcoming lectures. 00:57.890 --> 01:04.210 For now, let's take with the very basic form of creating a YAML file 01:04.210 --> 01:07.680 using a VI editor on my Linux system. 01:07.680 --> 01:10.090 Here I am on my Linux terminal, 01:10.090 --> 01:15.960 and I'm going to make use of a Vim text-based editor to create this pod definition file. 01:15.960 --> 01:20.090 The name of the file, I'm going to call as pod.yaml, 01:20.090 --> 01:22.000 and as seen in the lecture, 01:22.000 --> 01:26.000 we will start off with the four root level elements 01:26.000 --> 01:28.800 or the root level properties that we saw 01:28.800 --> 01:33.130 which are API version kind metadata and spec. 01:33.650 --> 01:39.130 We know that the value for API version for a pod is V1, 01:39.130 --> 01:42.970 the kind is a Pod with a capital P. 01:44.140 --> 01:47.930 It is case-sensitive, that's important. 01:47.930 --> 01:53.240 Metadata is a dictionary and it can have values where we define the name of the pod. 01:53.240 --> 01:56.300 I'm going to use name as NGINX 01:56.300 --> 02:01.740 and we can have additional labels that we can specify under it. 02:01.740 --> 02:08.480 Labels, again, is also a dictionary and it can have as many labels as you want under it. 02:08.480 --> 02:14.420 We can specify a label which is a key-value pairs, just a app and NGINX. 02:14.420 --> 02:21.140 We can also add more labels like tier and set it to front end, 02:21.140 --> 02:24.890 anything that can help us group this particular pod. 02:25.160 --> 02:30.540 Next, we have to define the spec. Spec is also a dictionary. 02:30.540 --> 02:33.020 It has an object called containers. 02:33.020 --> 02:34.840 Before we move on to that, 02:34.840 --> 02:38.970 we have to make sure that we get the indentation right. 02:38.970 --> 02:44.090 For example, the app and tier are children of the labels property. 02:44.090 --> 02:48.040 It has to be in the same vertical line here. 02:48.040 --> 02:50.120 Similarly, under metadata, 02:50.120 --> 02:53.720 you have name and labels which are the children of metadata. 02:53.720 --> 02:58.410 They both have to be within the same vertical line. 02:58.410 --> 03:01.290 You have to make sure that the spacing is correct. 03:01.290 --> 03:08.260 Typically, it would be two spaces or a tab, but it is recommended not to use tabs. 03:08.260 --> 03:13.320 Always stick to two spaces and stick to that throughout. 03:13.320 --> 03:17.400 The next thing that we're going to configure is the container. 03:17.400 --> 03:20.320 A container is a list of objects. 03:20.320 --> 03:22.480 Now, we first give it a name. 03:22.480 --> 03:26.450 Note that this is the name of the container within the pod, 03:26.450 --> 03:30.890 and there could be multiple containers and each can have a different name. 03:30.890 --> 03:36.680 One container could be named app and another container could be named helper. 03:36.680 --> 03:39.200 Any name that makes sense to you, 03:39.200 --> 03:42.720 we're going to use the same name as that of the container image. 03:42.720 --> 03:45.650 We will just name it, NGINX. 03:46.900 --> 03:50.960 The second object that we're going to add here is the image name, 03:50.960 --> 03:55.730 which is the Docker Hub image name of the container that we're going to create. 03:56.420 --> 03:59.620 The image name is again, NGINX. 04:00.120 --> 04:02.780 If you're using other registries than Docker Hub, 04:02.780 --> 04:08.400 then make sure to specify the full path to that image repository here. 04:08.640 --> 04:13.120 Now, remember that we can add additional containers to the pod as well. 04:13.120 --> 04:19.200 If you have to do that, we have to declare the secondary element to the list, 04:19.200 --> 04:21.840 which would be the second object in the list. 04:21.840 --> 04:27.050 Here, I can, for example, add a BusyBox container using the BusyBox image, 04:27.050 --> 04:29.890 and that would be the second element of theory. 04:30.810 --> 04:35.080 In this case, we're going to stick to one single container. 04:35.080 --> 04:37.760 I'm going to just delete that. 04:40.250 --> 04:45.440 I'm now going to hit Escape:wq to save this file. 04:45.440 --> 04:47.570 We will just use the cut command 04:47.570 --> 04:52.570 to make sure that the file was created with the expected contents. 04:52.690 --> 04:54.860 Make sure the format is correct. 04:54.860 --> 04:58.200 The name and labels are children of metadata, 04:58.200 --> 05:02.850 and you can see that they are on the same vertical line. 05:02.850 --> 05:07.610 Similarly, labels have two children which are the two labels, app and tier. 05:07.610 --> 05:15.730 Spec has a list, and we are defining it as a list with a hyphen followed by the objects. 05:18.250 --> 05:23.840 We can make use of the kubectl create command or the kubectl apply command. 05:23.840 --> 05:27.970 The create and apply command works the same. 05:28.610 --> 05:33.660 If you're creating a new object, you can either use create or use apply. 05:33.660 --> 05:35.130 It doesn't matter. 05:35.690 --> 05:40.160 We passing the file name using the -f option. 05:40.160 --> 05:43.690 Here, we can see that the pod has been created. 05:43.690 --> 05:46.580 Let's check the status real quick. 05:47.120 --> 05:50.380 You can see that it's in ContainerCreating state, 05:50.380 --> 05:53.610 then when we check again, we see that it's in a running state. 05:53.610 --> 05:56.260 As before, if you want to get more details about the pod, 05:56.260 --> 06:01.890 you can always run the kubectl describe command and specify the name of the pod. 06:01.890 --> 06:06.500 You should get a much more in-depth information about the pod. 06:06.500 --> 06:08.420 That's it for this demo. 06:08.420 --> 06:12.050 In the next section, we will learn some tips and tricks 06:12.050 --> 06:17.260 of developing YAML files easily using IDEs.