WEBVTT 00:01.320 --> 00:02.153 Instructor: In the last section, 00:02.153 --> 00:03.480 we spoke about some of the different config 00:03.480 --> 00:05.700 that we put into our persistent volume claim. 00:05.700 --> 00:07.170 Now at the end of last section 00:07.170 --> 00:09.840 I had mentioned that there are some other possible options 00:09.840 --> 00:11.280 so we could put inside of here. 00:11.280 --> 00:13.050 We did not put these options in because 00:13.050 --> 00:16.650 we are going to rely upon the defaults for each of these 00:16.650 --> 00:18.270 but there's one option in particular 00:18.270 --> 00:20.880 that I want to mention because it might be very important 00:20.880 --> 00:24.120 for you to use at some point in time in the future. 00:24.120 --> 00:24.953 Okay? 00:24.953 --> 00:27.840 So I want you to imagine kind of what happens 00:27.840 --> 00:30.840 behind the scenes when we hand that persistent volume claim 00:30.840 --> 00:32.550 off to Kubernetes. 00:32.550 --> 00:34.800 And so if we look back at the diagram over here 00:34.800 --> 00:37.900 remember at some point in time we hand that pod config off 00:38.829 --> 00:41.970 and Kubernetes sees, oh, they want that 500 gigabyte option. 00:41.970 --> 00:44.280 So Kubernetes has to like go and find 00:44.280 --> 00:47.400 either that pre configured pre-created ahead of time, 00:47.400 --> 00:49.920 persistent volume, or make one on the fly. 00:49.920 --> 00:52.410 So think about what's going on behind the scenes there. 00:52.410 --> 00:54.120 We're essentially saying to Kubernetes, 00:54.120 --> 00:56.550 Hey I need one gigabyte worth of storage. 00:56.550 --> 00:59.130 Can you get me something that meets these requirements? 00:59.130 --> 01:01.830 That's what the persistent volume claim is really doing. 01:01.830 --> 01:03.210 So Kubernetes gets that 01:03.210 --> 01:05.760 and then we're going to imagine what exactly happens 01:05.760 --> 01:08.760 on your computer when you run this stuff. 01:08.760 --> 01:10.620 We can kind of imagine that Kubernetes probably 01:10.620 --> 01:12.540 says something like, All right, well 01:12.540 --> 01:15.660 I'm on this developer's personal laptop 01:15.660 --> 01:17.940 or maybe I'm on their personal desktop. 01:17.940 --> 01:20.070 Not a lot of storage options available here. 01:20.070 --> 01:22.830 Like pretty much all I've got to put any information 01:22.830 --> 01:24.660 in is your hard drive. 01:24.660 --> 01:26.190 So on your computer 01:26.190 --> 01:28.620 why default Kubernetes is gonna say, You know what? 01:28.620 --> 01:30.750 I'm gonna make a slice of your hard drive. 01:30.750 --> 01:32.913 That is one gigabyte large. 01:33.810 --> 01:35.670 And so we can imagine on your hard drive 01:35.670 --> 01:37.980 we get this one gigabyte little piece 01:37.980 --> 01:41.490 of your hard drive that is going to be a persistent volume 01:41.490 --> 01:43.140 and that persistent volume gets handed 01:43.140 --> 01:45.570 back over to your pod. 01:45.570 --> 01:46.860 So on your computer, 01:46.860 --> 01:49.500 when you ask Kubernetes for some amount of storage, 01:49.500 --> 01:51.270 there's really just one place 01:51.270 --> 01:53.550 for Kubernetes to allocate that storage. 01:53.550 --> 01:54.720 It's just your hard drive 01:54.720 --> 01:57.810 and there's really not a lot of other options. 01:57.810 --> 01:59.100 Now, you can actually see 01:59.100 --> 02:01.830 in the Kubernetes config where it decides to 02:01.830 --> 02:04.020 make this the default where it decides to say 02:04.020 --> 02:06.000 I'm just gonna put it on your hard drive. 02:06.000 --> 02:08.350 To do so, you can flip on over to your terminal 02:09.210 --> 02:14.210 and run Cube ctl get storage class. 02:14.910 --> 02:16.470 So when you run get storage class 02:16.470 --> 02:19.500 you're gonna see all the different options on your computer 02:19.500 --> 02:23.700 that Kubernetes has for creating a persistent volume. 02:23.700 --> 02:26.700 Right now, we have a single option called standard. 02:26.700 --> 02:28.440 It is the default option. 02:28.440 --> 02:31.110 So if we do not specify a storage class 02:31.110 --> 02:32.790 with our persistent volume claim 02:32.790 --> 02:36.150 the standard option will be used by default 02:36.150 --> 02:38.100 and the provisioner or essentially 02:38.100 --> 02:42.180 how Kubernetes is going to decide how to provision 02:42.180 --> 02:44.520 or create this persistent volume is 02:44.520 --> 02:47.940 by using the mini cube host path option. 02:47.940 --> 02:50.940 And I want you to also do a cube CTL describe 02:50.940 --> 02:52.680 storage class as well, 02:52.680 --> 02:54.390 and you'll see some more information 02:54.390 --> 02:56.250 about that option right there. 02:56.250 --> 02:59.220 So when you do so, it tells you in very broad terms, 02:59.220 --> 03:02.970 Yes, we have a provisioner that is mini cube, host path. 03:02.970 --> 03:06.480 Mini cube host path means exactly what we saw over here. 03:06.480 --> 03:07.980 Mini cube host path means that when 03:07.980 --> 03:11.220 we ask Kubernetes to create this persistent volume 03:11.220 --> 03:14.370 it's going to look on the host machine to mini cube 03:14.370 --> 03:15.840 and it's gonna make a little slice 03:15.840 --> 03:18.780 of space on your personal hard drive. 03:18.780 --> 03:20.430 All right, so at this point, this probably seems, 03:20.430 --> 03:22.260 you know at least somewhat palatable, like, yeah 03:22.260 --> 03:23.580 Kubernetes need some space. 03:23.580 --> 03:25.260 It's gonna try to claim some space 03:25.260 --> 03:28.230 off of your computer or your personal hard drive. 03:28.230 --> 03:31.320 But things start to get way more complicated when 03:31.320 --> 03:33.510 we start to move our Kubernetes cluster 03:33.510 --> 03:37.533 from your computer into a cloud environment. 03:38.460 --> 03:40.800 So at some point in time, you and I are going to 03:40.800 --> 03:43.350 move our application over to a cloud provider. 03:43.350 --> 03:45.450 And when we are working with a cloud provider 03:45.450 --> 03:48.690 we get a tremendous number of different options 03:48.690 --> 03:50.370 of where some hard drive space 03:50.370 --> 03:53.940 or essentially file system space can be sourced from. 03:53.940 --> 03:57.510 So in a cloud or production environment, if we say, Hey 03:57.510 --> 03:59.850 I need one gigabyte of storage to Kubernetes 03:59.850 --> 04:01.710 Kubernetes is gonna then say, 04:01.710 --> 04:03.390 Great, which one do you want? 04:03.390 --> 04:06.480 I got like a billion options available. 04:06.480 --> 04:08.310 And so just about every cloud provider 04:08.310 --> 04:09.660 that you're going to work with is going to 04:09.660 --> 04:14.040 have some different solution for storing information. 04:14.040 --> 04:15.900 And you need to tell Kubernetes 04:15.900 --> 04:17.490 unless you wanna use the default option 04:17.490 --> 04:20.460 which of these different options you want to use. 04:20.460 --> 04:23.130 So if you are hosting an application on Google Cloud 04:23.130 --> 04:26.100 the Google Cloud service called Persistent Disc is 04:26.100 --> 04:28.890 going to be used to store information 04:28.890 --> 04:30.570 with your persistent volume. 04:30.570 --> 04:31.950 If you're on Microsoft Azure 04:31.950 --> 04:34.080 you can either use Azure file or Azure disc. 04:34.080 --> 04:37.680 If you're on AWS, you will use AWS Block Store. 04:37.680 --> 04:39.810 Now, there's many other options that are available 04:39.810 --> 04:41.250 in a cloud environment. 04:41.250 --> 04:42.083 You can see some 04:42.083 --> 04:44.583 of the other options at this address right here. 04:46.020 --> 04:48.090 I actually already opened up that page. 04:48.090 --> 04:51.660 So on that page you'll see storage classes. 04:51.660 --> 04:54.780 And if you scroll down to Provisioner, 04:54.780 --> 04:57.120 the provisioner is essentially what determines 04:57.120 --> 05:00.330 how this space you're asking for gets created. 05:00.330 --> 05:01.950 And so these are all the different options 05:01.950 --> 05:03.300 that you have available. 05:03.300 --> 05:06.030 You can look that list and decide on which one you want 05:06.030 --> 05:08.580 but I can tell you that by default, most of the time 05:08.580 --> 05:10.710 you're probably going to want whatever the default is 05:10.710 --> 05:13.290 for your particular cloud provider, which on, say 05:13.290 --> 05:15.300 Google Cloud, it's gonna be persistent disc 05:15.300 --> 05:18.030 on AWS it's going to be block Store. 05:18.030 --> 05:19.890 Now, when you create your Kubernetes cluster 05:19.890 --> 05:23.280 on a cloud provider like Google Cloud or AWS, 05:23.280 --> 05:25.290 one of these services is going to be set up 05:25.290 --> 05:27.000 by default for you. 05:27.000 --> 05:30.030 So in other words, right now inside 05:30.030 --> 05:32.340 of our local environment, we are setting 05:32.340 --> 05:35.160 up this persistent volume claim without designating 05:35.160 --> 05:37.950 a storage class name. 05:37.950 --> 05:39.450 And we did not designate that option 05:39.450 --> 05:41.490 because we are relying upon the default. 05:41.490 --> 05:44.130 And like I just said, the default for us is to 05:44.130 --> 05:47.340 create a little slice on our hard drive to use 05:47.340 --> 05:49.200 for this persistent volume. 05:49.200 --> 05:51.630 But when you push your application up to Kubernetes 05:51.630 --> 05:53.730 on Google Cloud or AWS, 05:53.730 --> 05:57.870 the standard option is not going to be mini cube host path. 05:57.870 --> 06:01.380 Instead, the standard option, or the default option for use 06:01.380 --> 06:04.890 on AWS or Google Cloud will be automatically configured 06:04.890 --> 06:08.070 for you to be either Google Cloud Persistent Disc 06:08.070 --> 06:10.530 or AWS Block store. 06:10.530 --> 06:12.330 So long story short here 06:12.330 --> 06:16.290 what I'm trying to tell you is that when you ask Kubernetes 06:16.290 --> 06:19.320 for some amount of storage on your local machine 06:19.320 --> 06:21.930 it's just gonna take a slice of your hard drive. 06:21.930 --> 06:23.430 When you are in a cloud environment 06:23.430 --> 06:26.400 it's going to choose one of these default options for you 06:26.400 --> 06:30.030 unless you very specifically tell it to use something else. 06:30.030 --> 06:32.130 For most applications, you know, 06:32.130 --> 06:34.710 I don't really want to make a broad claim here 06:34.710 --> 06:35.610 but I'm gonna tell you that 06:35.610 --> 06:37.680 if you've got a normal application that just 06:37.680 --> 06:41.610 has a traditional database like Postgres or MySQL 06:41.610 --> 06:44.490 you're probably going to be okay using the default options 06:44.490 --> 06:46.320 which are probably going to usually be 06:46.320 --> 06:49.290 Google Cloud persistent Disc or AWS Block Store. 06:49.290 --> 06:51.630 But I just want you to know that this option is available 06:51.630 --> 06:54.510 and you can customize where Kubernetes is going to 06:54.510 --> 06:57.600 look to create this little file system to allocate 06:57.600 --> 06:58.980 to your pod. 06:58.980 --> 07:01.410 All right, So enough on all this 07:01.410 --> 07:04.413 I think we've spoken about persistent volume claims enough. 07:05.400 --> 07:07.740 So we've now created our persistent volume claim 07:07.740 --> 07:11.340 which is essentially advertising an option that can be used 07:11.340 --> 07:14.310 for storage by all the different pods in our application. 07:14.310 --> 07:16.560 So last thing we have to do in the next section 07:16.560 --> 07:19.380 we're going to open up our Postgres deployment 07:19.380 --> 07:23.130 and we're going to update the pod config in here and tell it 07:23.130 --> 07:26.910 that when this pod is created, it's going to need to look 07:26.910 --> 07:29.130 at all the different storage options that are available 07:29.130 --> 07:31.920 and advertised by this persistent volume claim 07:31.920 --> 07:33.300 and make sure that it says, 07:33.300 --> 07:36.420 Oh yeah I want this very specific volume claim 07:36.420 --> 07:39.120 that's going to give me a two gigabyte storage option. 07:39.120 --> 07:41.570 So quick pause and I'll see you in just a minute.