WEBVTT 00:00.930 --> 00:01.763 -: In the last section, 00:01.763 --> 00:03.660 we put together our very first Docker file 00:03.660 --> 00:05.430 and then very quickly used it 00:05.430 --> 00:07.830 at the terminal to build a new image. 00:07.830 --> 00:09.030 However, we didn't really talk 00:09.030 --> 00:10.830 about what was going on inside of here. 00:10.830 --> 00:13.800 So in this section and the next, I wanna do a deep dive 00:13.800 --> 00:16.830 on all the configuration that we added to the Docker file 00:16.830 --> 00:20.160 and also what happened over at the terminal afterwards. 00:20.160 --> 00:21.183 So let's get to it. 00:22.320 --> 00:23.153 All right. 00:23.153 --> 00:25.560 So I took every line outta that Docker file except 00:25.560 --> 00:28.290 for the comments and put it into this diagram right here. 00:28.290 --> 00:31.740 So you see from Alpine, run and command, 00:31.740 --> 00:33.540 you'll notice that every line of configuration 00:33.540 --> 00:34.380 that we put in there 00:34.380 --> 00:36.930 looked kind of similar to the others. 00:36.930 --> 00:39.210 Every line started off with a single word 00:39.210 --> 00:41.640 that we refer to as an instruction. 00:41.640 --> 00:44.370 This instruction is telling the Docker server 00:44.370 --> 00:47.400 to do some very specific preparation step 00:47.400 --> 00:50.160 on the image that we are trying to create. 00:50.160 --> 00:52.410 The instruction from is used 00:52.410 --> 00:54.240 to specify the Docker image 00:54.240 --> 00:56.880 that we want to use as a base. 00:56.880 --> 01:00.330 The run instruction is used to execute some command 01:00.330 --> 01:03.270 while we are preparing our custom image. 01:03.270 --> 01:04.380 And then the CMD 01:04.380 --> 01:07.080 or command instruction specifies, 01:07.080 --> 01:09.000 what should be executed 01:09.000 --> 01:10.140 when our container, sorry, 01:10.140 --> 01:13.830 when our image is used to start up a brand new container. 01:13.830 --> 01:16.260 Every line of configuration that you are ever going to add 01:16.260 --> 01:18.540 to a docker file is always gonna start off 01:18.540 --> 01:19.833 with an instruction. 01:20.760 --> 01:22.440 Now, we just used the three most 01:22.440 --> 01:23.970 important instructions to know, 01:23.970 --> 01:25.980 there are quite another, 01:25.980 --> 01:28.470 quite a handful of other instructions out there. 01:28.470 --> 01:30.120 We're gonna look at a handful of them 01:30.120 --> 01:31.410 throughout the rest of this course. 01:31.410 --> 01:33.870 But again, from, run and CMD 01:33.870 --> 01:36.960 are the most important ones to know and understand. 01:36.960 --> 01:39.660 After each instruction, we then provided an argument 01:39.660 --> 01:41.640 to the instruction that kind of customized 01:41.640 --> 01:43.680 how that instruction was executed. 01:43.680 --> 01:46.080 So as you might guess, by putting from Alpine 01:46.080 --> 01:50.234 we are saying we want to use a base image of Alpine 01:50.234 --> 01:52.650 when preparing our image, 01:52.650 --> 01:53.820 and we'll talk more about exactly 01:53.820 --> 01:56.520 what that base image is doing for us in just a moment. 01:57.360 --> 02:01.200 On the next one, we said we want to run this command. 02:01.200 --> 02:02.640 This command was the argument 02:02.640 --> 02:04.560 that was provided to the instruction. 02:04.560 --> 02:06.810 And then for CMD down here at the bottom, well, 02:06.810 --> 02:10.050 I bet you can guess, yeah, that is the argument to cmd. 02:10.050 --> 02:11.550 All right, so that's what was going on 02:11.550 --> 02:14.700 with the overall structure of the Docker file. 02:14.700 --> 02:17.100 But that doesn't really explain a lot of the pieces 02:17.100 --> 02:19.950 or kinda like what the intent of each of these lines were 02:19.950 --> 02:22.620 outside of the comments that we added on there 02:22.620 --> 02:24.300 while we were writing the Docker file. 02:24.300 --> 02:25.620 So let's take a quick pause. 02:25.620 --> 02:27.000 We're gonna come back to the next section 02:27.000 --> 02:27.870 and we're gonna start to look 02:27.870 --> 02:29.100 at the output that we got 02:29.100 --> 02:32.070 inside of our terminal and try to understand 02:32.070 --> 02:35.006 how each of those lines of configuration was interpreted 02:35.006 --> 02:38.460 by the Docker server and used to build our image. 02:38.460 --> 02:40.910 So quick break and I'll see you in just a minute.