1 00:00:02,340 --> 00:00:04,960 So that's it for this module. 2 00:00:04,960 --> 00:00:08,230 Again, another large module with a lot of content 3 00:00:08,230 --> 00:00:10,320 and a lot of explanations in it, 4 00:00:10,320 --> 00:00:12,910 but we had a look at a couple of key concepts 5 00:00:12,910 --> 00:00:16,140 which you have to know when you're working with Docker. 6 00:00:16,140 --> 00:00:19,040 We learned that containers can read and write data 7 00:00:19,040 --> 00:00:22,070 but that volumes can help us with storing data 8 00:00:22,070 --> 00:00:26,180 especially with data that should survive container removal. 9 00:00:26,180 --> 00:00:28,530 We also had a look at bind mounts 10 00:00:28,530 --> 00:00:31,950 which can help us with direct container interaction. 11 00:00:31,950 --> 00:00:33,930 For example, with our source code, 12 00:00:33,930 --> 00:00:38,250 that should be updatable by us and where the latest source 13 00:00:38,250 --> 00:00:40,300 code should then always be available 14 00:00:40,300 --> 00:00:41,950 inside of the container. 15 00:00:41,950 --> 00:00:45,050 But let's go through what we learned step-by-step. 16 00:00:45,050 --> 00:00:47,630 Containers are the heart of Docker 17 00:00:47,630 --> 00:00:51,140 and they can already read and write data. 18 00:00:51,140 --> 00:00:53,950 They do add this read-write layer 19 00:00:53,950 --> 00:00:56,410 on top of your image after all 20 00:00:57,570 --> 00:01:01,050 but data, which you write inside of a container is lost 21 00:01:01,050 --> 00:01:02,870 if that container is removed. 22 00:01:02,870 --> 00:01:05,560 Because of that isolation concept 23 00:01:05,560 --> 00:01:08,810 often that's useful but sometimes it's not. 24 00:01:08,810 --> 00:01:12,440 Pretty much every application has some kind of data 25 00:01:12,440 --> 00:01:15,930 which should survive, which should persist. 26 00:01:15,930 --> 00:01:18,300 And that's why you can add volumes. 27 00:01:18,300 --> 00:01:21,560 Volumes in the end are folders on your host machine 28 00:01:21,560 --> 00:01:23,360 on which your containers are running, 29 00:01:23,360 --> 00:01:24,950 which are managed by Docker 30 00:01:24,950 --> 00:01:28,450 and which are mounted into a Docker container. 31 00:01:28,450 --> 00:01:30,130 There is this connection 32 00:01:30,130 --> 00:01:34,180 between the paths which are mapped inside of a container 33 00:01:34,180 --> 00:01:38,180 and the automatically created folder on your host machine. 34 00:01:38,180 --> 00:01:41,180 And whatever is written into that mapped path 35 00:01:41,180 --> 00:01:42,430 inside of the container, 36 00:01:42,430 --> 00:01:45,710 is also stored on the host machine therefore, 37 00:01:45,710 --> 00:01:49,970 and hence this data survives if the container is removed, 38 00:01:49,970 --> 00:01:53,170 because it's basically mirrored or copied 39 00:01:53,170 --> 00:01:54,560 to the host machine 40 00:01:54,560 --> 00:01:58,203 and not just stored inside off the container. 41 00:01:59,400 --> 00:02:02,860 Now specifically, we learned about two kinds of volumes. 42 00:02:02,860 --> 00:02:06,580 Named volumes are useful because of these survive 43 00:02:06,580 --> 00:02:08,120 if a container is removed 44 00:02:08,120 --> 00:02:10,720 and they offer, these are the volumes we need 45 00:02:10,720 --> 00:02:13,420 if we wanna store data permanently. 46 00:02:13,420 --> 00:02:17,300 Anonymous volumes are actually attached to a container 47 00:02:17,300 --> 00:02:19,970 and are removed if the container are removed 48 00:02:19,970 --> 00:02:23,530 and therefore they're not useful for storing permanent data, 49 00:02:23,530 --> 00:02:25,660 which should persist. 50 00:02:25,660 --> 00:02:29,660 They can still be useful to save temporary data 51 00:02:29,660 --> 00:02:32,570 make D container a bit more efficient 52 00:02:32,570 --> 00:02:35,760 because less data has to be stored in the container. 53 00:02:35,760 --> 00:02:39,490 More data can be outsourced to the host system. 54 00:02:39,490 --> 00:02:44,100 And we also saw that they can help us with bind mounts 55 00:02:44,100 --> 00:02:47,910 because bind mounts allow us to map local folders 56 00:02:47,910 --> 00:02:51,200 on the host machine, which we, as a developer know 57 00:02:51,200 --> 00:02:53,800 two internal folders into container 58 00:02:53,800 --> 00:02:57,990 for example, to expose our source code to the container. 59 00:02:57,990 --> 00:03:01,170 And then we can combine that with anonymous volumes 60 00:03:01,170 --> 00:03:05,550 to not accidentally override folders that already existed 61 00:03:05,550 --> 00:03:08,113 in the container, which we don't wanna override. 62 00:03:09,290 --> 00:03:11,630 Bind mounts are a bit like named volumes 63 00:03:11,630 --> 00:03:13,860 but the key differences that we know 64 00:03:13,860 --> 00:03:17,380 the path on the host machine, where the data is mirrored, 65 00:03:17,380 --> 00:03:20,890 and that we actually use that path to pass data 66 00:03:20,890 --> 00:03:23,690 into the container and to actually pass data 67 00:03:23,690 --> 00:03:26,980 into the container which we can change on the host machine. 68 00:03:26,980 --> 00:03:29,870 And where then the latest data is always available 69 00:03:29,870 --> 00:03:30,800 in the container. 70 00:03:30,800 --> 00:03:33,420 Like we did it with our source code. 71 00:03:33,420 --> 00:03:37,370 Now you can set up these volumes on the Docker run command 72 00:03:37,370 --> 00:03:39,400 with the -v option. 73 00:03:39,400 --> 00:03:41,930 Here we have a named volume 74 00:03:41,930 --> 00:03:45,000 and Docker automatically creates these volumes for you. 75 00:03:45,000 --> 00:03:47,430 If they don't exist yet, if they do exist 76 00:03:47,430 --> 00:03:49,810 it uses the existing ones instead. 77 00:03:49,810 --> 00:03:53,570 Here, we set up a bind mount by mapping an absolute path 78 00:03:53,570 --> 00:03:57,310 on our local machine to an internal path into container. 79 00:03:57,310 --> 00:03:59,520 And here we set up an anonymous volume. 80 00:03:59,520 --> 00:04:02,300 Here we do the same to simply make sure 81 00:04:02,300 --> 00:04:05,250 that certain folders inside of the container 82 00:04:05,250 --> 00:04:09,020 are not overridden by the bind mount in this case. 83 00:04:09,020 --> 00:04:10,140 And last but not least, 84 00:04:10,140 --> 00:04:12,290 we also had a look at build arguments 85 00:04:12,290 --> 00:04:14,360 and runtime environment variables 86 00:04:14,360 --> 00:04:16,399 which simply can make our images 87 00:04:16,399 --> 00:04:19,649 and containers a bit more dynamic and configurable 88 00:04:19,649 --> 00:04:22,890 since we can pass in certain pieces of data 89 00:04:22,890 --> 00:04:25,250 from outside when we built the image 90 00:04:25,250 --> 00:04:27,280 or when we ran the container. 91 00:04:27,280 --> 00:04:29,920 And we don't have to hard code everything 92 00:04:29,920 --> 00:04:33,130 into the Docker file or into our source code. 93 00:04:33,130 --> 00:04:36,040 Instead, we can configure this when we run the container 94 00:04:36,040 --> 00:04:38,550 and that can be useful as well. 95 00:04:38,550 --> 00:04:40,770 And that's what we learned in this module 96 00:04:40,770 --> 00:04:44,290 as always definitely feel free to go back 97 00:04:44,290 --> 00:04:46,650 to certain lectures and go through them again. 98 00:04:46,650 --> 00:04:50,010 If certain concepts should not be entirely clear by now 99 00:04:50,010 --> 00:04:51,410 in the next module, 100 00:04:51,410 --> 00:04:54,120 we're going to dive even deeper into Docker. 101 00:04:54,120 --> 00:04:56,080 And we're also going to explore 102 00:04:56,080 --> 00:04:58,700 how we can actually use multiple containers 103 00:04:58,700 --> 00:05:02,090 running different applications, and how we can ensure 104 00:05:02,090 --> 00:05:05,220 that these containers can then work together. 105 00:05:05,220 --> 00:05:07,400 Also quite interesting this year 106 00:05:07,400 --> 00:05:10,850 is an important of foundation, which we need for debt. 107 00:05:10,850 --> 00:05:13,273 So make sure we're all on the same page.