WEBVTT 00:00.840 --> 00:01.673 -: In the last section, 00:01.673 --> 00:03.480 we went over the behind the scenes flow 00:03.480 --> 00:05.850 of what occurred during that Docker build process. 00:05.850 --> 00:07.260 Now that was a rather long section 00:07.260 --> 00:09.120 and we went through a lot of detail. 00:09.120 --> 00:11.460 So in this section I wanna do a quick recap, 00:11.460 --> 00:12.690 just a very quick overview 00:12.690 --> 00:15.690 on the really important critical flow to understand. 00:15.690 --> 00:17.130 Now, if you don't wanna hear me lecture 00:17.130 --> 00:18.060 about this stuff anymore, 00:18.060 --> 00:20.250 if you feel like you already have a good understanding, 00:20.250 --> 00:21.990 no problem, pause the video right now 00:21.990 --> 00:23.550 and move on to the next section. 00:23.550 --> 00:25.110 Again, we're only gonna do a recap 00:25.110 --> 00:27.330 of what we just spoke about a moment ago. 00:27.330 --> 00:30.630 Okay, so here's the recap with a slightly different diagram. 00:30.630 --> 00:33.960 So everything started with the affirm Alpine instruction. 00:33.960 --> 00:36.480 That told the Docker server or Docker daemon 00:36.480 --> 00:38.730 to go and download the Alpine image. 00:38.730 --> 00:41.340 And we use the Alpine image as a base because 00:41.340 --> 00:44.370 it comes pre-installed with some really handy programs 00:44.370 --> 00:47.013 that are useful for us creating our image. 00:48.330 --> 00:49.380 The next thing that occurred 00:49.380 --> 00:53.580 was the run instruction was executed by the Docker server. 00:53.580 --> 00:55.890 The first thing that occurred there was it looked 00:55.890 --> 00:58.380 for the image from the previous step, 00:58.380 --> 01:00.090 and so it went back to the previous step 01:00.090 --> 01:03.093 and got the Alpine image that had just been downloaded. 01:04.110 --> 01:06.780 That image was then used to create a brand new 01:06.780 --> 01:08.760 very temporary container. 01:08.760 --> 01:10.680 So here's our container over here 01:10.680 --> 01:13.050 and then the command that we had specified, 01:13.050 --> 01:15.930 so apk add --update redis 01:15.930 --> 01:18.903 was executed inside of that temporary container. 01:19.770 --> 01:22.170 The APK program was executed. 01:22.170 --> 01:23.910 It downloaded and installed Redis 01:23.910 --> 01:26.670 inside the file system of that container. 01:26.670 --> 01:30.240 So the result is a container with a modified file system. 01:30.240 --> 01:32.733 It now has Redis added onto it. 01:34.200 --> 01:37.620 We then took a snapshot of that container's new file system 01:37.620 --> 01:40.380 and the result was a file system snapshot. 01:40.380 --> 01:42.450 We then shut down the temporary container, 01:42.450 --> 01:45.180 like this one right here that had just been created, 01:45.180 --> 01:48.690 and we got our image ready for the next instruction. 01:48.690 --> 01:52.350 And the image that we're using is that file system snapshot, 01:52.350 --> 01:54.360 the modified one that we just created 01:54.360 --> 01:56.580 when we installed Redis. 01:56.580 --> 01:57.900 So you can now imagine 01:57.900 --> 02:00.330 that we are now passing on to the next step. 02:00.330 --> 02:03.270 We are essentially passing along the Alpine image, 02:03.270 --> 02:06.213 but with Redis added on top. 02:07.380 --> 02:10.680 So we then move on to the command Redis server instruction. 02:10.680 --> 02:13.020 We again get the image from the previous step. 02:13.020 --> 02:15.390 We again create a temporary container out of it, 02:15.390 --> 02:16.290 but this time around, 02:16.290 --> 02:18.810 rather than executing a command inside there, 02:18.810 --> 02:21.240 which is the purpose of the run instruction, 02:21.240 --> 02:23.640 we instead use the CMD instruction, 02:23.640 --> 02:27.030 which is used to specify what the container should do, 02:27.030 --> 02:28.170 or excuse me, what the image should do 02:28.170 --> 02:30.393 when it is started up as a container. 02:31.830 --> 02:34.410 So we told the temporary container that we just created 02:34.410 --> 02:36.480 that whenever it gets started in the future, 02:36.480 --> 02:40.290 it should try to execute the command redis-server. 02:40.290 --> 02:41.850 And the result was a container 02:41.850 --> 02:44.343 that has a modified primary command. 02:45.210 --> 02:47.340 We then shut down that temporary container 02:47.340 --> 02:49.920 and we got it ready, where you took an image out of it, 02:49.920 --> 02:52.260 and got it ready for the next instruction. 02:52.260 --> 02:54.450 But in that case, there are no more instructions, 02:54.450 --> 02:57.180 no more steps to execute inside this file. 02:57.180 --> 03:00.060 And so the output of the overall series of steps 03:00.060 --> 03:02.190 is whatever image was generated 03:02.190 --> 03:06.120 during the last instruction inside of our Docker file. 03:06.120 --> 03:08.040 All right, so like I said, just a quick recap 03:08.040 --> 03:11.400 on that entire process one more time, because it is, 03:11.400 --> 03:12.570 it's not super critical 03:12.570 --> 03:14.100 that you have an in-depth understanding here, 03:14.100 --> 03:16.260 but it definitely makes a lot of this Docker stuff 03:16.260 --> 03:20.910 a lot easier if you have a good grasp on this entire flow. 03:20.910 --> 03:22.440 So let's take a quick pause right here 03:22.440 --> 03:24.390 and we'll continue in the next section.