WEBVTT 00:00.810 --> 00:02.940 -: In the last section, we created our Docker file 00:02.940 --> 00:05.940 and built a new image for our new application. 00:05.940 --> 00:07.800 We should now be able to start up our application 00:07.800 --> 00:10.020 by running Docker Run, 00:10.020 --> 00:12.390 and then we'll specify the image we just created. 00:12.390 --> 00:17.283 So you will put in your Docker username/visits. 00:19.080 --> 00:22.170 Now remember, you do not have to specify the tag 00:22.170 --> 00:25.260 by putting on :latest at the end, 00:25.260 --> 00:27.270 but you optionally can if you want to. 00:27.270 --> 00:28.530 So we can run this right here 00:28.530 --> 00:30.480 and it will start up our application. 00:30.480 --> 00:32.640 Now you'll notice that we immediately get an error message, 00:32.640 --> 00:33.750 it says Redis connection 00:33.750 --> 00:36.300 to something, something, something failed. 00:36.300 --> 00:38.430 So our application is attempting to start up 00:38.430 --> 00:41.640 but there's no Redis server running for it to connect to. 00:41.640 --> 00:43.200 So in this section, we're gonna focus on 00:43.200 --> 00:47.340 getting a separate container running a Redis server. 00:47.340 --> 00:50.490 Now, as far as getting up a separate Redis server goes, 00:50.490 --> 00:52.560 well, it's gonna be pretty darn straightforward. 00:52.560 --> 00:54.150 We're gonna run the same exact command 00:54.150 --> 00:56.430 that we've ran throughout this course. 00:56.430 --> 01:01.430 I'll run Docker Run Redis like so. 01:01.632 --> 01:03.420 And so, that's gonna reach out to the Docker Hub, 01:03.420 --> 01:05.040 it's gonna pull down the Redis instance 01:05.040 --> 01:07.830 and it'll start up a copy of Redis on our local machine. 01:07.830 --> 01:10.470 And boom, just like that, there's our Redis server. 01:10.470 --> 01:12.330 So that's it, that's the Redis instance. 01:12.330 --> 01:14.100 We're gonna use no customization 01:14.100 --> 01:16.890 to the Docker image for it whatsoever. 01:16.890 --> 01:18.349 So now that we have our Docker, 01:18.349 --> 01:19.740 excuse me, our Redis server running, 01:19.740 --> 01:22.380 I'm gonna open up a second terminal window 01:22.380 --> 01:23.790 and inside the second window 01:23.790 --> 01:28.350 I'll now try running Docker Run my image again. 01:28.350 --> 01:32.223 So I'll say Docker Run StevenGrider/visits. 01:33.510 --> 01:34.353 Let's run that. 01:35.760 --> 01:36.900 And you'll notice, 01:36.900 --> 01:39.180 well, it looks like we still have the same error message 01:39.180 --> 01:42.900 we had before, even though we are now running a Redis server 01:42.900 --> 01:44.520 inside of a separate container. 01:44.520 --> 01:46.140 So what's the problem? 01:46.140 --> 01:48.600 Well, let's think about it for a second. 01:48.600 --> 01:50.850 Here's what's going on on your computer right now. 01:50.850 --> 01:53.550 You've got a Node application in one container 01:53.550 --> 01:57.450 and the Redis application in the separate Docker container. 01:57.450 --> 02:01.020 Now, these two containers do not have any automatic 02:01.020 --> 02:03.180 communication between the two whatsoever. 02:03.180 --> 02:06.510 They are two absolutely isolated processes 02:06.510 --> 02:08.640 that don't have any communication. 02:08.640 --> 02:11.130 So in order to make sure that our Node app has the ability 02:11.130 --> 02:13.020 to kind of reach out to the Redis server 02:13.020 --> 02:15.810 and store information or work with it in some fashion, 02:15.810 --> 02:18.330 we need to set up some networking infrastructure 02:18.330 --> 02:20.010 between the two. 02:20.010 --> 02:22.230 Now, when it comes to setting up some networking 02:22.230 --> 02:24.510 functionality between two separate containers, 02:24.510 --> 02:27.603 we have for right now, two options to look at. 02:28.860 --> 02:30.420 So here's our two options. 02:30.420 --> 02:32.130 We can either make use of the Docker CLI 02:32.130 --> 02:34.650 that we've been making use of throughout this course so far. 02:34.650 --> 02:36.600 I'm talking about the Docker command 02:36.600 --> 02:37.890 that we've been using at our terminal 02:37.890 --> 02:39.720 throughout this entire course. 02:39.720 --> 02:42.150 This built in Docker CLI has functionality 02:42.150 --> 02:44.610 tied to it that will allow us to set up a network 02:44.610 --> 02:47.010 between two separate containers. 02:47.010 --> 02:49.050 However, there's a little issue with it, 02:49.050 --> 02:50.250 and the issue is basically, 02:50.250 --> 02:53.550 just that it's a real pain in the neck to do. 02:53.550 --> 02:55.980 When you make use of Docker CLI to set up some networking, 02:55.980 --> 02:58.740 it's going to involve a handful of different commands 02:58.740 --> 03:00.960 that have to be reran every single time 03:00.960 --> 03:04.410 you start up your different containers. 03:04.410 --> 03:06.510 Now, of course, we could make some type of little script 03:06.510 --> 03:07.680 to run all that stuff for us 03:07.680 --> 03:09.990 but certainly it's gonna involve a lot of typing 03:09.990 --> 03:11.700 and a lot of thought on how we're gonna set up 03:11.700 --> 03:13.350 all this networking stuff. 03:13.350 --> 03:15.960 I'm gonna be honest with you, I have just about never seen 03:15.960 --> 03:20.960 people in industry ever making use of the Docker CLI. 03:21.090 --> 03:22.320 Let me be very clear here, 03:22.320 --> 03:25.200 never making use of Docker CLIs built in networking features 03:25.200 --> 03:27.450 to connect two containers together. 03:27.450 --> 03:29.280 Much more frequently, what you're going to see, 03:29.280 --> 03:31.500 and what you and I are going to do inside this course, 03:31.500 --> 03:35.670 is we're gonna make use of a separate CLI tool 03:35.670 --> 03:37.563 called Docker Compose. 03:38.910 --> 03:42.240 Docker Compose is a separate tool that gets installed 03:42.240 --> 03:43.410 along with Docker. 03:43.410 --> 03:46.380 So if you, right now flip back over to your terminal 03:46.380 --> 03:50.040 and run Docker-Compose, like so, 03:50.040 --> 03:52.080 you should see some content appear on the screen 03:52.080 --> 03:53.670 and will list out a series of different commands 03:53.670 --> 03:54.503 for you to run. 03:56.250 --> 03:58.350 Docker Compose is a separate CLI, 03:58.350 --> 04:00.330 it's already installed on your machine. 04:00.330 --> 04:02.550 Now when you start introducing Docker Compose, 04:02.550 --> 04:04.860 it's gonna very quickly starting getting confusing 04:04.860 --> 04:07.710 what Docker Compose does and what Docker CLI does, 04:07.710 --> 04:09.900 and what the relationship between the two is. 04:09.900 --> 04:11.430 So the best thing I could tell you, 04:11.430 --> 04:14.610 is that Docker Compose really exists to keep you 04:14.610 --> 04:16.290 from having to write out a ton 04:16.290 --> 04:20.340 of different repetitive commands with the Docker CLI. 04:20.340 --> 04:21.870 So throughout this course, we've been running stuff 04:21.870 --> 04:24.750 like Docker Run and Docker Attach and Exec 04:24.750 --> 04:26.760 and we've been specifying ports and tags 04:26.760 --> 04:28.713 and all this stuff just all the time. 04:29.580 --> 04:31.470 Now, definitely as we learn this stuff, 04:31.470 --> 04:33.810 we need to use Docker CLI and learn it. 04:33.810 --> 04:35.227 But at a certain point in time you say, 04:35.227 --> 04:37.860 "Okay, I understand this Docker CLI stuff," 04:37.860 --> 04:39.960 and you get tired of writing out those commands. 04:39.960 --> 04:42.510 And so one of the big purposes of Docker Compose 04:42.510 --> 04:45.000 is to just avoid having to write out all these really 04:45.000 --> 04:47.220 annoying tiny little options every time 04:47.220 --> 04:48.870 you want to start up a container. 04:50.130 --> 04:51.480 The other big thing that Docker Compose 04:51.480 --> 04:54.480 is going to do for us, is it's going to make it very easy 04:54.480 --> 04:56.430 and very straightforward to start up multiple 04:56.430 --> 04:58.230 Docker containers at the same time, 04:58.230 --> 05:00.270 and automatically connect them together 05:00.270 --> 05:02.400 with some form of networking. 05:02.400 --> 05:03.233 And it's all gonna happen 05:03.233 --> 05:06.120 behind the scenes for us quite automatically. 05:06.120 --> 05:08.520 So again, as soon as you start seeing this terminology here 05:08.520 --> 05:09.960 of Docker Compose, 05:09.960 --> 05:12.360 keeping all these Docker terms straight in your head 05:12.360 --> 05:13.620 gets a little bit confusing. 05:13.620 --> 05:14.790 But I'm gonna tell you this right now, 05:14.790 --> 05:16.410 I'm gonna repeat it several times. 05:16.410 --> 05:19.110 The purpose of Docker Compose is to essentially 05:19.110 --> 05:22.710 function as Docker CLI but allow you to kind of issue 05:22.710 --> 05:25.050 multiple commands much more quickly. 05:25.050 --> 05:26.670 So let's take a quick break right here. 05:26.670 --> 05:27.870 We're gonna come back to the next section 05:27.870 --> 05:29.700 and we're gonna get a little bit more familiar 05:29.700 --> 05:31.653 with Docker Compose and how it works.