WEBVTT 00:00.840 --> 00:01.640 Before we move on. 00:01.640 --> 00:06.320 There's just one last little quick thing that I want to show you around this entire image building process. 00:06.440 --> 00:10.360 Now, what I'm going to show you inside this section is not something that you're probably going to 00:10.360 --> 00:15.480 do very often or ever, really, but it's something I thought you might find a little bit interesting 00:15.480 --> 00:20.440 and help you get a little bit of a better handle on the relationship between an image and a container. 00:21.000 --> 00:25.400 When we were going over the flow of actions that occurred while we were building the image, we spoke 00:25.400 --> 00:27.960 about how we take an image from the previous step. 00:27.960 --> 00:33.240 We create a container out of it, we do something with that container, and we then essentially create 00:33.240 --> 00:38.640 an image out of that running container or that kind of very temporary, temporary container that was 00:38.640 --> 00:39.280 created. 00:39.880 --> 00:45.400 So at this point, you and I know very well that we use images to create containers, but based on everything 00:45.400 --> 00:50.240 that we've been talking about in this section, it sure seems like the opposite is kind of true as well. 00:50.240 --> 00:54.880 It seems like we can kind of take a container and generate an image out of it as well. 00:55.160 --> 00:56.880 And that actually is correct. 00:56.920 --> 01:02.830 You and I can manually create a container, run some commands inside of it, or change its file system 01:03.030 --> 01:07.590 and then generate a usable image that we can then use at some point in the future. 01:07.870 --> 01:13.430 In other words, we can kind of very manually do the same thing that our Docker file does. 01:13.830 --> 01:20.590 We can create a container, run a command like say apk, add this right here and then generate an image 01:20.590 --> 01:21.310 out of that. 01:21.350 --> 01:23.150 I want to very quickly show you how that would look. 01:23.150 --> 01:26.270 But again, I really don't expect you to do this on your own personal project. 01:26.270 --> 01:29.750 I'm just showing you this as kind of something you might find interesting. 01:30.670 --> 01:34.510 So let's try to kind of emulate the Docker file that we just put together. 01:34.510 --> 01:38.150 We're going to create a new container manually out of the alpine image. 01:38.270 --> 01:40.510 We're then going to install Redisai on it. 01:40.550 --> 01:45.830 We're then going to set up a default command and generate a usable image that can be used in the future. 01:45.830 --> 01:48.470 Essentially everything that our Docker file just did. 01:49.030 --> 01:51.830 So at my terminal I'm going to execute docker run. 01:51.830 --> 01:56.150 And we're going to start up a shell inside of here so that we can run a couple of commands inside of 01:56.150 --> 01:56.630 it. 01:56.630 --> 02:02.330 So I'm going to put on the IT flag I'll put on alpine as our image. 02:02.330 --> 02:06.850 And then the command that I want to execute inside there is sh to start up a shell. 02:07.730 --> 02:13.170 So then I get presented with a command prompt right here that is inside of that running container now. 02:13.210 --> 02:20.490 And so inside that container I'm going to manually install Redice by running APK add dash dash update 02:20.610 --> 02:22.050 redice like so. 02:22.730 --> 02:27.450 So we now have a running container where we have modified its file system. 02:27.450 --> 02:31.490 And the file system has now seen the installation of Redice. 02:32.170 --> 02:33.690 So we've got the running container. 02:33.930 --> 02:36.370 I'm now going to open up a second terminal window. 02:36.730 --> 02:41.170 And inside of here I'm going to run a command using the Docker CLI. 02:41.330 --> 02:47.570 That's going to essentially take a snapshot of that running container and assign a default command to 02:47.610 --> 02:50.530 it and generate an image out of the entire thing. 02:51.050 --> 02:56.410 So to do so I'll say first docker PS to get the ID of that running container. 02:56.930 --> 02:59.730 And then we'll do docker commit. 03:00.170 --> 03:05.840 I'm going to add on a dash C right here, which is going to allow us to specify the default command. 03:06.200 --> 03:07.560 So I'm going to say dash C. 03:07.800 --> 03:14.800 And then I'll put in cmd double quotes inside of the square brace Redice dash server. 03:15.080 --> 03:16.560 I'll close the double quotes. 03:16.600 --> 03:19.240 I'll close the square brace and I'll close the single quotes. 03:19.240 --> 03:23.600 So notice how we have a single quote, single quote, and double quotes around it. 03:24.160 --> 03:28.320 And then after all that, I'll paste the ID of that running container. 03:28.800 --> 03:30.480 So I'm going to paste it in like so. 03:31.520 --> 03:37.200 And the output is the ID of a new image that we just customized for our own uses. 03:37.520 --> 03:40.040 Now you'll notice that this is a really long ID right here. 03:40.080 --> 03:42.400 One shortcut that I haven't quite mentioned so far. 03:42.560 --> 03:47.880 Whenever you're making use of IDs or hashes in the Docker world, you don't have to copy the entire 03:47.880 --> 03:48.280 thing. 03:48.400 --> 03:53.120 You can just copy a segment of the start, and it's kind of assumed that this is going to be unique 03:53.120 --> 03:56.880 enough that Docker is going to take this and realize that, oh, you're probably talking about this 03:56.880 --> 03:58.280 very long ID right here. 03:58.640 --> 04:02.420 So I'm going to copy just an arbitrary number of leading characters here. 04:02.740 --> 04:08.460 And then we'll do a Docker run that, and that's going to start up a new container out of the image 04:08.460 --> 04:09.780 that we just created. 04:10.180 --> 04:14.140 And inside that running container we already have this installed. 04:14.180 --> 04:17.420 And the default starting command will be to run Redisai server. 04:17.900 --> 04:23.260 So let's run that and we'll very quickly see all the typical output that we see from a running Redisai 04:23.300 --> 04:23.980 instance. 04:24.500 --> 04:24.860 All right. 04:24.860 --> 04:30.940 So like I said, we basically just very manually created a container, added a dependency to the container, 04:31.900 --> 04:35.740 set up the default command, and then generated an image out of all that. 04:36.100 --> 04:38.580 Again you really don't want to use that practice. 04:38.580 --> 04:39.060 In general. 04:39.100 --> 04:41.540 You don't use Docker commit in general. 04:41.540 --> 04:46.860 You really want to use the Docker file approach, because it allows you to very easily rerun that series 04:46.860 --> 04:48.140 of steps again in the future. 04:48.140 --> 04:52.940 But again, I just thought you might find it interesting how yes, there really is a very kind of fluid 04:52.940 --> 04:55.620 relationship between containers and images. 04:56.100 --> 04:56.540 All right. 04:56.540 --> 05:00.140 So let's take another quick pause right here and we'll move on to the next section.