1 00:00:01,382 --> 00:00:04,090 Now, before we dig into kubernetes 2 00:00:04,090 --> 00:00:07,840 and volumes there is a certain term which I wanna clarify, 3 00:00:07,840 --> 00:00:10,250 and that would be State. 4 00:00:10,250 --> 00:00:13,590 You could kind of translate state with data, 5 00:00:13,590 --> 00:00:16,590 in the end it's just data which is created 6 00:00:16,590 --> 00:00:20,790 and used by your application which must not be lost. 7 00:00:20,790 --> 00:00:24,180 And there are different kinds of such state. 8 00:00:24,180 --> 00:00:27,050 There for example is user-generated data, 9 00:00:27,050 --> 00:00:28,980 like to story where storing 10 00:00:28,980 --> 00:00:32,183 or something like a user account which was created. 11 00:00:33,040 --> 00:00:36,130 There also are intermediate results 12 00:00:36,130 --> 00:00:37,720 which are derived by the app 13 00:00:37,720 --> 00:00:39,850 and which are also needed 14 00:00:39,850 --> 00:00:42,853 but which eventually will be lost and cleared. 15 00:00:43,860 --> 00:00:46,000 Now the user-generated to data, 16 00:00:46,000 --> 00:00:49,070 the user accounts and whatever your app is about 17 00:00:49,070 --> 00:00:52,270 that data is typically stored in databases 18 00:00:52,270 --> 00:00:56,620 but maybe also in files, Like in the example I gave you 19 00:00:56,620 --> 00:01:01,620 where we store the data in this story text file. 20 00:01:02,450 --> 00:01:04,910 Now for the intermediate results that 21 00:01:04,910 --> 00:01:07,740 is often storage Just in memory 22 00:01:07,740 --> 00:01:11,380 or in temporary database tables or files. 23 00:01:11,380 --> 00:01:14,090 But whichever kind of data you're dealing with, 24 00:01:14,090 --> 00:01:17,350 the key thing is that this data needs 25 00:01:17,350 --> 00:01:19,640 to survive container restarts, 26 00:01:19,640 --> 00:01:22,170 especially the data on the left side, of course, 27 00:01:22,170 --> 00:01:25,670 and that is exactly what we have volumes for. 28 00:01:25,670 --> 00:01:28,940 This is nothing new and nothing kubernetes specific, 29 00:01:28,940 --> 00:01:31,600 I just want us to emphasize does again, 30 00:01:31,600 --> 00:01:33,780 that is why we use volumes 31 00:01:33,780 --> 00:01:38,040 because this data matters and must not be lost just 32 00:01:38,040 --> 00:01:40,920 because a container is stopped and was removed. 33 00:01:40,920 --> 00:01:45,240 And it does not matter if we're working with Docker locally 34 00:01:45,240 --> 00:01:47,510 and with Docker and Docker compose, 35 00:01:47,510 --> 00:01:49,860 or if we're working with kubernetes 36 00:01:49,860 --> 00:01:53,113 because we wanna deploy that data onto a cluster. 37 00:01:54,180 --> 00:01:56,590 Especially, if we work with kubernetes 38 00:01:56,590 --> 00:01:59,680 and we are planning to deploy our application 39 00:01:59,680 --> 00:02:04,430 we of course need to ensure that crucial data is not lost. 40 00:02:04,430 --> 00:02:07,470 I mean, your application wouldn't be worth much 41 00:02:07,470 --> 00:02:11,160 if your user data would suddenly be gone, right? 42 00:02:11,160 --> 00:02:13,400 So that's why we have volumes 43 00:02:13,400 --> 00:02:16,100 and of course we already know that solution. 44 00:02:16,100 --> 00:02:18,530 As I mentioned, we already know volumes 45 00:02:18,530 --> 00:02:22,210 and volumes still matter when working with kubernetes 46 00:02:22,210 --> 00:02:26,320 because ultimately we're still dealing with containers. 47 00:02:26,320 --> 00:02:30,940 So of course, this solution for persisting data 48 00:02:30,940 --> 00:02:34,100 which we already learned about is not obsolete, 49 00:02:34,100 --> 00:02:36,040 we still need it. 50 00:02:36,040 --> 00:02:38,700 However, we of course have to keep in mind 51 00:02:38,700 --> 00:02:42,050 that now when working with kubernetes, 52 00:02:42,050 --> 00:02:45,110 it's kubernetes that runs our containers. 53 00:02:45,110 --> 00:02:48,450 It's not us, we don't run Docker run 54 00:02:48,450 --> 00:02:50,550 or a Docker Compose command. 55 00:02:50,550 --> 00:02:54,780 Instead, we use kubernetes and we orchestrate 56 00:02:54,780 --> 00:02:58,090 our cluster and our deployment with kubernetes 57 00:02:58,090 --> 00:03:00,810 and kubernetes then creates these pods 58 00:03:00,810 --> 00:03:03,070 which then run our containers. 59 00:03:03,070 --> 00:03:06,490 So we don't directly launch our containers. 60 00:03:06,490 --> 00:03:08,220 And therefore of course, 61 00:03:08,220 --> 00:03:10,970 we can't provide a Docker compose file 62 00:03:10,970 --> 00:03:15,380 and we can't add the dash V flag when using Docker run, 63 00:03:15,380 --> 00:03:18,770 instead we need to configure Kubernetes such 64 00:03:18,770 --> 00:03:21,360 that it adds volumes to our containers. 65 00:03:21,360 --> 00:03:23,560 And that's exactly what we're going to dive into 66 00:03:23,560 --> 00:03:26,280 in this module, in this course section. 67 00:03:26,280 --> 00:03:30,830 How we can get Kubernetes to create and add volumes 68 00:03:30,830 --> 00:03:33,703 to the containers it starts for us.