WEBVTT 00:00.780 --> 00:01.613 Instructor: In the last section, 00:01.613 --> 00:04.350 we put together our first persistent volume claim. 00:04.350 --> 00:06.720 Now, before we talk about what the spec stuff 00:06.720 --> 00:09.840 inside of here is, I wanna give you a very quick reminder. 00:09.840 --> 00:12.090 Remember that a volume claim 00:12.090 --> 00:14.790 is not an actual instance of storage. 00:14.790 --> 00:17.760 A volume claim is something that we are going to attach 00:17.760 --> 00:19.230 to a pod config. 00:19.230 --> 00:20.910 So back in our example over here, 00:20.910 --> 00:23.250 we would take this volume claim that says, 00:23.250 --> 00:26.190 hey, I can get you a 500 gigabyte hard drive 00:26.190 --> 00:29.400 and we attach it to our pod config. 00:29.400 --> 00:30.540 Then at some point in time, 00:30.540 --> 00:34.500 we take that pod config and we hand it off to Kubernetes. 00:34.500 --> 00:37.290 Kubernetes is going to see that storage option, 00:37.290 --> 00:39.120 it's gonna see that volume claim, 00:39.120 --> 00:40.440 and it's going to try to find 00:40.440 --> 00:43.050 either a statically provision, persistent volume 00:43.050 --> 00:45.990 or a dynamically provision, persistent volume 00:45.990 --> 00:48.840 to meet the requirements of that claim. 00:48.840 --> 00:50.490 So all to config that you and I have now 00:50.490 --> 00:53.130 added in underneath the spec section is saying, 00:53.130 --> 00:55.680 that if we attach this claim to a pod, 00:55.680 --> 00:58.950 Kubernetes must find an instance of storage, 00:58.950 --> 01:00.690 like a slice of your hard drive 01:00.690 --> 01:03.540 that meets these requirements. 01:03.540 --> 01:04.530 So with that in mind, 01:04.530 --> 01:06.993 let's talk about what an access mode is. 01:08.040 --> 01:09.600 All right, so access modes. 01:09.600 --> 01:12.240 We get three different types of access modes. 01:12.240 --> 01:15.030 The one that we used is ReadWriteOnce. 01:15.030 --> 01:17.790 ReadWriteOnce means that we want to get some 01:17.790 --> 01:20.430 instance of storage like a slice of your hard drive 01:20.430 --> 01:23.580 that can be used by a single node at a time. 01:23.580 --> 01:26.850 And to be precise, that single node can use it 01:26.850 --> 01:30.570 and both read and write information to that volume. 01:30.570 --> 01:34.560 We also get access to an access mode of ReadOnlyMany, 01:34.560 --> 01:37.560 which means that multiple nodes at the same time 01:37.560 --> 01:40.830 can read information from this persistent volume. 01:40.830 --> 01:42.270 And then finally, ReadWriteMany 01:42.270 --> 01:44.970 means that we can both read and write information 01:44.970 --> 01:49.080 to this persistent volume by many nodes at the same time. 01:49.080 --> 01:51.870 Now, again, I want to really, really highlight the fact 01:51.870 --> 01:54.390 that the access mode that we put in right here says, 01:54.390 --> 01:56.760 if you attach me to a pod config 01:56.760 --> 01:58.710 and then hand me off to Kubernetes, 01:58.710 --> 02:01.650 Kubernetes is going to have to find an instance 02:01.650 --> 02:04.533 of storage that supports this access mode. 02:06.540 --> 02:08.670 All right, so let's now move on to resources down here. 02:08.670 --> 02:11.610 Now, I bet you can really guess what's going on here. 02:11.610 --> 02:14.070 So with storage, we're essentially saying 02:14.070 --> 02:17.640 that Kubernetes is going to have to find a storage option, 02:17.640 --> 02:20.820 either one that has been provisioned ahead of time 02:20.820 --> 02:23.040 or one that is going to be created on the fly 02:23.040 --> 02:25.260 that has at least two gigabytes of space. 02:25.260 --> 02:26.460 Or to be exact, 02:26.460 --> 02:29.343 it has to have exactly two gigabytes of space. 02:30.840 --> 02:33.090 We could very easily change this number around, 02:33.090 --> 02:36.660 we can say, 1000 gigabytes or four, six, 02:36.660 --> 02:37.800 whatever you want it to be. 02:37.800 --> 02:41.070 But for us, two is way more than what is needed 02:41.070 --> 02:44.640 to put together our very simple Postgres database. 02:44.640 --> 02:47.760 In fact, we're gonna use like fractions of a kilobyte. 02:47.760 --> 02:50.850 So two gigabytes is way overkill for our application 02:50.850 --> 02:52.500 but I just wanna give you an example 02:52.500 --> 02:55.230 with a gigabyte option here. 02:55.230 --> 02:57.540 Okay, so these two options right here, 02:57.540 --> 02:58.740 pretty straightforward in nature. 02:58.740 --> 03:00.810 Again, they are saying, hey, Kubernetes, 03:00.810 --> 03:03.540 you have to find a storage instance 03:03.540 --> 03:04.890 that has this access mode 03:04.890 --> 03:08.400 and it has to have exactly two gigabytes worth of storage. 03:08.400 --> 03:11.310 Now, there's a couple of other options 03:11.310 --> 03:13.530 so we can add into this file that we did not 03:13.530 --> 03:16.020 because we're going to rely upon the defaults 03:16.020 --> 03:18.600 but these other storage options that we did not list out 03:18.600 --> 03:20.370 are pretty important to understand. 03:20.370 --> 03:21.570 So let's take a quick break. 03:21.570 --> 03:22.950 When we come back to the next section, 03:22.950 --> 03:24.603 we'll talk about some other possible options 03:24.603 --> 03:28.320 that we could put into this spec if you had need to do so. 03:28.320 --> 03:30.770 So quick pause and I'll see you in just a minute.