WEBVTT 00:00.350 --> 00:01.160 Welcome back. 00:01.160 --> 00:06.230 Now go ahead and open up the workbook starter projects. 00:06.530 --> 00:12.950 Uh, now we're going to run a Ruby app, a Python app, as well as a go app without installing any of 00:12.950 --> 00:16.670 their respective, uh, environments into our machine. 00:16.670 --> 00:20.900 Everything is going to happen inside of Docker itself. 00:20.900 --> 00:23.000 Let's start with the Ruby application. 00:23.000 --> 00:29.150 So many of you are probably not familiar with Ruby, uh, and probably never will use Ruby after this 00:29.150 --> 00:30.050 course. 00:30.050 --> 00:31.280 And that's okay. 00:31.280 --> 00:37.970 We're just going to run a simple Ruby application for the sake of demonstrating that regardless of whatever 00:38.030 --> 00:41.750 app you're running, the process is going to be similar. 00:41.900 --> 00:48.290 Okay, now, am I going to force you to install the Ruby environment into your machine just to run this 00:48.290 --> 00:48.620 app? 00:48.620 --> 00:55.220 No, everything is going to happen inside of Docker itself, which is the beauty of running Docker containers. 00:55.220 --> 01:00.560 So here, the developer who created this app, they're telling us how to run it bare metal. 01:00.560 --> 01:05.660 We are going to modify the command so that it runs within our container properly. 01:05.660 --> 01:07.790 So let's go ahead and create a docker container. 01:07.790 --> 01:10.010 Docker run dash v. 01:11.140 --> 01:17.170 Actually, before we do any mounting, we're going to specify the flag dash dash RM to remove the container 01:17.170 --> 01:18.430 once we're done with it. 01:18.550 --> 01:21.730 And dash v we're going to use to mount. 01:21.730 --> 01:23.770 Let's go to the ruby schematic. 01:26.220 --> 01:34.740 We're going to use it to mount the source code that is inside of our host machine into a working directory 01:34.740 --> 01:36.630 within our Docker container. 01:37.080 --> 01:37.920 All right. 01:37.920 --> 01:41.160 So we need to get the path. 01:43.460 --> 01:52.670 Where our code lives in our machine and mount it into some working directory inside of our container. 01:52.670 --> 01:57.980 You can call the working directory whatever you want, as long as you're consistent when you provide 01:57.980 --> 02:00.200 the container with a command. 02:01.960 --> 02:06.670 We're going to call the container, uh, Ruby application. 02:08.460 --> 02:10.170 And the container. 02:10.170 --> 02:14.130 Now it has the application mounted at the working directory. 02:14.160 --> 02:19.080 Now it needs a Ruby environment in order to run this app. 02:19.080 --> 02:22.230 Going over to Docker Hub, let's write Ruby. 02:23.500 --> 02:28.090 And this is the official repo for a bunch of Ruby images. 02:28.330 --> 02:34.060 Uh, we're going to get the Ruby image tagged 3.0.0. 02:34.060 --> 02:34.960 Okay. 02:39.620 --> 02:46.730 And let's go ahead and pull Ruby 3.0.0 into our Docker container. 02:46.730 --> 02:50.510 So at this point our container has the Ruby image. 02:50.510 --> 02:56.660 Remember an image is a snapshot of a preconfigured environment taken at a specific point in time that 02:56.660 --> 03:00.770 we can use to run this Ruby app. 03:00.770 --> 03:03.830 So now we can provide the container with the command Ruby. 03:05.300 --> 03:08.750 Slash app slash scriptdb. 03:08.780 --> 03:15.890 So it's using the Ruby command to run the script dot rb file that it's going to be inside of the container's 03:15.890 --> 03:17.240 working directory. 03:17.270 --> 03:18.770 Let's go ahead and run this. 03:18.800 --> 03:21.650 It's unable to find the ruby image locally. 03:21.650 --> 03:29.690 So it's going to pull this pre-configured ruby environment into our local Docker cache, where our container 03:29.690 --> 03:35.540 can have direct access to it and thereby execute this Ruby command on our app. 03:35.540 --> 03:37.760 And that's exactly what it did. 03:37.790 --> 03:38.240 All right. 03:38.270 --> 03:41.900 Now let's move on to the Python script. 03:42.230 --> 03:43.280 All right. 03:43.280 --> 03:46.100 So let's go ahead and press clear. 03:46.100 --> 03:54.620 And I'm going to go to my Docker dashboard which you can access on Mac by going over here and clicking 03:54.620 --> 04:00.710 on the go to dashboard icon on windows by going over to the bottom right toolbar, clicking the bottom, 04:00.710 --> 04:02.090 clicking the Docker icon. 04:02.090 --> 04:03.410 It'll take you here. 04:03.440 --> 04:07.910 Remember what's nice about Docker is everything happens inside of it. 04:07.910 --> 04:11.690 So by virtue of removing this Ruby image. 04:12.730 --> 04:15.340 It's like nothing ever happened. 04:15.960 --> 04:18.630 There is no trace of any ruby. 04:19.720 --> 04:25.450 Activity on our system, and there are no containers because we specify dash dash m. 04:25.660 --> 04:27.160 Now we move on. 04:27.990 --> 04:29.310 To the Python app. 04:29.310 --> 04:34.800 So again we're going to mount the Python app into the working directory of whatever container we create. 04:34.800 --> 04:39.360 We're going to pull a Python environment so that our container can use it. 04:40.300 --> 04:40.990 Um. 04:41.940 --> 04:47.970 Then we're going to run the Python application by giving it command line arguments as well. 04:47.970 --> 04:53.970 So the script.py file was programmed to accept command line arguments. 04:53.970 --> 05:01.230 So when we provide the container with the uh with the executing command, we need to make sure to give 05:01.230 --> 05:04.530 it the arguments that the application expects. 05:04.530 --> 05:05.910 All right. 05:05.910 --> 05:11.760 So let's say Docker run and we're going to create a container that automatically gets removed. 05:11.760 --> 05:14.850 Once we're done with it then we're going to say volume mount. 05:14.850 --> 05:18.000 We're going to mount we're going to get the path. 05:19.010 --> 05:24.410 The folder where the application lives, and we're going to mount whatever is inside of the Python script 05:24.410 --> 05:28.580 folder into a working directory within our container. 05:28.610 --> 05:32.750 We're going to call the container Python script container. 05:33.110 --> 05:39.200 And we're going to create we're going to pull the image Python 3.8 slim. 05:39.200 --> 05:44.360 So we're so for the sake of exercise we're going to locate it within Docker Hub. 05:44.600 --> 05:46.580 Go to the official Python repo. 05:46.580 --> 05:47.960 With all of the images. 05:47.960 --> 05:52.610 We're going to look for the image tagged 3.8 slim. 05:53.770 --> 05:55.450 This one right here. 05:55.450 --> 06:01.090 We're going to pull that so that our container can use it to execute the command. 06:01.090 --> 06:03.400 Python script.py. 06:03.670 --> 06:08.560 And the application that exists at our container's working directory. 06:08.560 --> 06:12.550 It expects command line arguments within the command itself. 06:12.550 --> 06:17.500 So um, we can just say hello from Docker. 06:17.500 --> 06:22.750 We're going to give it three command line arguments unable to find the image locally. 06:22.750 --> 06:25.030 So we pull it from Docker Hub. 06:25.810 --> 06:28.570 Can't open file script.py. 06:28.600 --> 06:31.870 No such file or directory I messed up. 06:31.870 --> 06:39.220 The application is inside of our container's working directory slash app, so I need to specify. 06:40.390 --> 06:47.890 Python slash app slash Script.py so that it can find the application within the working directory that 06:47.890 --> 06:49.180 we mounted it to. 06:49.180 --> 06:56.350 And then we give that application the command line arguments that it that it that it is expecting. 06:56.470 --> 06:57.310 All right. 06:57.310 --> 06:59.320 Hello from Docker. 06:59.710 --> 07:02.650 And so now we move on to the go application. 07:03.820 --> 07:08.980 Uh, this app expects an environment variable named message to customize the greeting. 07:09.010 --> 07:17.380 Now, an environment variable is a key value pair that an application expects to receive from the environment 07:17.380 --> 07:18.460 that it's running in. 07:18.460 --> 07:26.140 So in this case, the container is going to be responsible for providing this application with the message 07:26.140 --> 07:30.670 environment variable so that this app can function accordingly. 07:30.700 --> 07:31.390 All right. 07:31.390 --> 07:38.560 So let's write clear to clear the output and create a container docker run dash dash rm that's going 07:38.560 --> 07:41.500 to mount the application at this path. 07:43.060 --> 07:47.800 Into the working directory of this Docker container. 07:49.410 --> 07:51.840 And we're going to call the container. 07:51.870 --> 07:52.830 Go. 07:54.050 --> 07:55.070 Container. 07:57.030 --> 07:59.640 And we're going to pull. 08:02.850 --> 08:09.900 The image Golang 1.16 into our container. 08:17.170 --> 08:18.880 1.16. 08:19.450 --> 08:22.180 Let's just verify the image. 08:22.420 --> 08:23.770 Make sure it exists. 08:23.770 --> 08:24.760 It does. 08:26.270 --> 08:33.560 So we're going to use this pre-configured Golang environment in order to run our application using the 08:33.560 --> 08:35.870 command go run. 08:35.900 --> 08:42.590 Now the Main.go file is going to be located within the container's working directory slash app. 08:42.590 --> 08:47.510 So we say go run slash app slash Main.go. 08:47.510 --> 08:54.290 And there's one thing I forgot to do, which is to provide this application that is going to be run 08:54.290 --> 08:57.470 within the container with environment variables. 08:57.470 --> 09:04.520 So when the container wants to provide its underlying application environment variables, it does so 09:04.520 --> 09:07.280 using the flag dash e. 09:07.880 --> 09:08.840 All right. 09:08.840 --> 09:14.990 And the environment variable that the app is expecting is called message. 09:14.990 --> 09:25.370 So we say dash e message is equal to some value which we can say hello from Docker. 09:26.680 --> 09:27.610 All right. 09:27.610 --> 09:29.620 And now if you press enter. 09:29.800 --> 09:34.960 Unable to find the Golang image locally so it pulls it from Docker Hub. 09:36.700 --> 09:43.090 And once it pulls the image, it can use it to execute the following command and run our go app. 09:43.120 --> 09:44.560 Beautiful. 09:44.590 --> 09:51.910 Our container was able to successfully run the go application and provide it with the environment variable 09:51.910 --> 09:54.310 that the app was expecting. 09:54.340 --> 10:02.770 Now I just want to note the difference between an environment variable that you see here, and the command 10:02.770 --> 10:06.190 line argument that we passed into the Python script. 10:06.310 --> 10:11.650 A command line argument is any value that you can pass directly to the application when running it from 10:11.650 --> 10:19.330 the command line, and an environment variable is a specific key value pair that an application is expecting 10:19.360 --> 10:22.420 to receive from the environment that it's running in. 10:22.420 --> 10:29.020 So command line argument any value environment variable it's expecting a particular key value pair. 10:29.050 --> 10:29.950 All right. 10:29.950 --> 10:36.010 So we were able to run a go application a Python application and a Ruby application without installing 10:36.010 --> 10:37.510 anything in our system. 10:37.510 --> 10:43.090 This would not change whether we're using Java, whether we're using C plus plus. 10:43.090 --> 10:48.880 You just need to make sure that you pull the appropriate image into the container. 10:48.880 --> 10:55.930 Once you have that image, you can run whatever commands you need to run in order to execute said app. 10:55.930 --> 10:59.680 Before we wrap up, go to your Docker dashboard. 10:59.680 --> 11:02.590 Delete all the images that we pulled. 11:03.380 --> 11:05.240 Uh, delete whatever. 11:05.240 --> 11:07.370 Containers haven't been deleted already. 11:07.370 --> 11:09.260 And you should be golden. 11:09.260 --> 11:13.610 I will see you in the next section when we discuss Docker files. 11:13.610 --> 11:14.750 See you then.