WEBVTT 00:00.600 --> 00:01.433 -: In the last section, 00:01.433 --> 00:03.180 we put together our first configuration file 00:03.180 --> 00:04.920 to create a deployment. 00:04.920 --> 00:06.030 In this section, we're going to 00:06.030 --> 00:07.710 walk through the configuration file 00:07.710 --> 00:09.390 and talk about a couple of interesting things 00:09.390 --> 00:10.860 that's inside of here. 00:10.860 --> 00:12.660 Now again, the first two lines that you see 00:12.660 --> 00:14.340 specify the API version 00:14.340 --> 00:16.650 and the object type that we want to create. 00:16.650 --> 00:20.070 So in this case, we're making an object of type deployment. 00:20.070 --> 00:23.040 After that, we see a very familiar metadata section 00:23.040 --> 00:25.320 that names the object that's going to be created 00:25.320 --> 00:27.120 by this configuration file. 00:27.120 --> 00:30.030 So in our our deployment deployment will have a name 00:30.030 --> 00:31.893 of client dash deployment. 00:33.120 --> 00:34.740 Now down in the spec section, 00:34.740 --> 00:38.250 I wanna skip on down to the template property right here. 00:38.250 --> 00:39.420 So inside the template, 00:39.420 --> 00:41.160 we're listing out the configuration 00:41.160 --> 00:43.980 that is going to be used for every single pod 00:43.980 --> 00:47.130 that is created by this deployment. 00:47.130 --> 00:49.230 The entire template section right here 00:49.230 --> 00:50.490 probably looks a little bit familiar 00:50.490 --> 00:52.350 to some of the configuration that we put together 00:52.350 --> 00:55.440 inside of our client pod dot yaml file. 00:55.440 --> 00:58.290 So back inside of client pod, we had a label. 00:58.290 --> 01:01.320 We had a list of containers assigned as well. 01:01.320 --> 01:02.970 And so you can essentially imagine 01:02.970 --> 01:04.560 that this template section right here 01:04.560 --> 01:07.830 is defining the exact configuration that should be used 01:07.830 --> 01:09.720 for every pod that is created 01:09.720 --> 01:12.390 and maintained by this deployment. 01:12.390 --> 01:14.160 Every pod that gets created by this deployment 01:14.160 --> 01:16.470 will have a label of component web 01:16.470 --> 01:19.440 and it will have a container with a name of client 01:19.440 --> 01:23.880 and using the image multi client with a port 3000 01:23.880 --> 01:25.353 mapped up to that container. 01:26.910 --> 01:28.530 Now, besides the template right here, 01:28.530 --> 01:30.360 the other properties that are kind of interesting 01:30.360 --> 01:33.210 is replicas and selector. 01:33.210 --> 01:34.980 So first off, replicas. 01:34.980 --> 01:36.720 As you might guess, this is specifying 01:36.720 --> 01:38.640 the number of different pods 01:38.640 --> 01:40.440 that this deployment is supposed to make. 01:40.440 --> 01:42.690 And remember, every one of those pods that it creates 01:42.690 --> 01:45.750 are going to be absolutely identical in nature. 01:45.750 --> 01:47.527 So at this point, we are saying, 01:47.527 --> 01:50.370 "Hey, deployment, create exactly one pod 01:50.370 --> 01:52.800 using this template down here." 01:52.800 --> 01:54.810 If we wanted to, we could very easily change this up 01:54.810 --> 01:56.400 to something like five. 01:56.400 --> 01:59.550 That means that we would want to create five separate pods 01:59.550 --> 02:02.493 each of which run this exactly identical template. 02:03.360 --> 02:06.603 We're going to leave replicas as one for right now, however. 02:07.470 --> 02:08.940 Now the other thing that's kind of interesting 02:08.940 --> 02:11.190 inside of here is the selector. 02:11.190 --> 02:14.250 The selector looks very similar to a selector property 02:14.250 --> 02:17.010 that we previously put into our node port file. 02:17.010 --> 02:19.833 So back over here we had a selector property as well. 02:20.940 --> 02:23.100 Let's talk about what the selector is. 02:23.100 --> 02:24.960 Essentially, it's doing something very similar 02:24.960 --> 02:25.890 to what the selector 02:25.890 --> 02:28.983 inside of the service configuration file was doing. 02:30.570 --> 02:32.850 You see, when a deployment creates a pod, 02:32.850 --> 02:37.350 it doesn't directly create the pod itself and maintain it. 02:37.350 --> 02:39.090 Instead, the deployment reaches out 02:39.090 --> 02:41.917 to the Kubernetes API on the master and it says, 02:41.917 --> 02:44.730 "Hey master, I need you to create a pod for me 02:44.730 --> 02:47.160 and here's the configuration for it." 02:47.160 --> 02:50.070 The master then goes ahead and creates the pod. 02:50.070 --> 02:53.160 Now it's the master or some program inside the master 02:53.160 --> 02:55.140 that is creating the pod for us. 02:55.140 --> 02:57.600 And so the deployment after the pod is created 02:57.600 --> 03:01.080 needs to somehow get a handle on the pod that is created 03:01.080 --> 03:03.810 and that's the purpose of that selector field. 03:03.810 --> 03:06.360 The deployment says, "Okay, I'm gonna ask master 03:06.360 --> 03:09.090 or some program in master to create this pod for me." 03:09.090 --> 03:12.180 After it gets created, I need to somehow get a handle on it. 03:12.180 --> 03:14.670 And so to get a handle on that newly created pod 03:14.670 --> 03:18.780 I'm gonna look for objects with a label of component web. 03:18.780 --> 03:19.613 And so of course 03:19.613 --> 03:22.260 every pod that we are creating using this deployment 03:22.260 --> 03:26.310 is going to have a label of component web 03:26.310 --> 03:29.700 because that's what we specified inside of our template. 03:29.700 --> 03:32.370 And so matched labels and selector right here. 03:32.370 --> 03:35.280 This section right here is essentially giving us a handle on 03:35.280 --> 03:37.410 this label down here. 03:37.410 --> 03:39.480 I know it seems a little bit repetitive 03:39.480 --> 03:41.880 to have to kind of like designate this stuff twice 03:41.880 --> 03:44.550 inside the same file, but it's entirely possible 03:44.550 --> 03:47.220 that we might have multiple labels assigned 03:47.220 --> 03:48.390 to our deployment 03:48.390 --> 03:50.910 or multiple labels assigned to the pod that is created 03:50.910 --> 03:52.050 by our deployment. 03:52.050 --> 03:54.840 And maybe we only want our deployment to look for 03:54.840 --> 03:57.363 one or two very specific labels out of those. 03:58.290 --> 03:59.370 So that's why you're seeing it 03:59.370 --> 04:02.070 kind of replicated here twice. 04:02.070 --> 04:03.120 Okay, so that's pretty much it 04:03.120 --> 04:05.670 for our deployment configuration file. 04:05.670 --> 04:07.020 So let's take a quick pause right here. 04:07.020 --> 04:08.280 We'll come back to the next section 04:08.280 --> 04:10.980 and we're going to apply this deployment file 04:10.980 --> 04:13.830 to our Kubernetes cluster by using Kubectl. 04:13.830 --> 04:15.420 And then we'll very quickly be able to 04:15.420 --> 04:17.460 look at a couple of interesting things 04:17.460 --> 04:20.640 around the deployment and the pod that is greeted with it. 04:20.640 --> 04:22.973 So quick break and I'll see you in just a minute.