00:00:00 Using Docker is super simple.

00:00:03 All you have to do is click the link in the description, download Docker Desktop for your own operating system, and that will help you containerize your

00:00:13 application in the easiest way possible.

00:00:17 It'll definitely take some time to download, but once you're there, you can accept the recommended settings and sign up.

00:00:24 Once you're in, on the left side, you can see the links to containers, which display the containers we've made, images, which shows the images we've built,

00:00:35 and volumes, which shows the shared volumes we have created for our containers, and other beta features like builds, dev environments,

00:00:45 and Docker scout.

00:00:47 Now, return to the browser and Google Docker Hub.

00:00:51 The first result will surely be hub.docker.com.

00:00:56 Then, open it up, go to Explore, and you can see all of the public images created so far by developers worldwide.

00:01:05 from official images by verified publishers to sponsored open source ones covering everything from operating system images like Ubuntu,

00:01:14 languages like Python and Golang, databases like Redis, Postgres, Mongo for MongoDB, MySQL, runtimes like Node.js, to even Hello World Docker image,

00:01:26 and also the old peeps like WordPress and PHP.

00:01:31 Almost everything that you need is right here.

00:01:34 But how do we create our own Docker images?

00:01:38 Easy peasy.

00:01:39 Creating a Docker image starts from a special file called Dockerfile.

00:01:44 It's a set of instructions telling Docker how to build an image for your application.

00:01:50 There are some specific instructions and keywords we use to tell Docker what we want through the Dockerfile.

00:01:57 Think of it as Docker syntax or language to specify exactly what we want.

00:02:03 Here are some of the commands.

00:02:05 From specifies the base image to use for the new image.

00:02:10 It's like picking a starting kitchen that already has some basic tools and ingredients.

00:02:15 WorkDir sets the working directory for the following instructions.

00:02:19 It's like deciding where in the kitchen you want to do all your cooking.

00:02:24 Copy copies the files or directories from the build context to the image.

00:02:29 It's like bringing in your recipe, ingredients, and any special tools into your chosen cooking spot.

00:02:35 Run executes commands in the shell during image build.

00:02:40 It's like doing specific steps of your recipe, such as mixing ingredients.

00:02:45 Expose informs Docker that the container will listen on specified network ports at runtime.

00:02:52 It's like saying, I'm going to use this specific part of the kitchen to serve the food.

00:02:57 ENV sets environment variables during the build process.

00:03:01 You can think of that as setting the kitchen environment, such as deciding whether it's a busy restaurant or a quiet home kitchen.

00:03:08 ARG defines build time variables.

00:03:12 It's like having a note that you can change before you start cooking, like deciding if you want to use fresh or frozen ingredients.

00:03:20 Volume creates a mount point for externally mounted volumes, essentially specifying a location inside your container where you can connect external storage.

00:03:31 It's like leaving a designated space in your kitchen for someone to bring in extra supplies if needed.

00:03:37 CMD provides default command to execute when the container starts.

00:03:42 It's like specifying what dish you want to make when someone orders from your menu.

00:03:47 EntryPoint specifies the default executable to be run when the container starts.

00:03:52 It's like having a default dish on your menu that people will get unless they specifically ask for something else.

00:03:59 And you might wonder, isn't EntryPoint the same as CMD?

00:04:04 Well, not really.

00:04:06 In simple terms, both CMD and EntryPoint are instructions in Docker for defining the default command to run when a container starts.

00:04:17 The key difference is that CMD is more flexible and can be overridden when running the container, while entry point defines the main command that cannot

00:04:27 be easily overridden.

00:04:29 Think of CMD as providing a default, which can be changed, and entry point as setting a fixed starting point for your container.

00:04:37 If both are used, CMD arguments will be passed to entry point.

00:04:42 And these are the most used keywords when creating a Docker file.

00:04:47 I have also prepared a list of other options you can use in Docker files.

00:04:51 You can think of it as a complete guide and a cheat sheet you can refer to when using Docker.

00:04:57 The link is in the description.

00:04:58 But now, let's actually use some of these commands in practice.

00:05:03 Let's try to run one of the images listed in the Docker Hub to see how that works.

00:05:08 Let's choose one of the operating system images as an example.

00:05:12 Let's go for Ubuntu.

00:05:14 On the right side of the details of the image, you'll see a command.

00:05:17 Copy it and try executing it in your terminal.

00:05:21 But before we paste it, first create a new empty folder on our desktop called Docker underscore course.

00:05:28 and then drag and drop it to our empty Visual Studio Code window.

00:05:33 Open up your empty terminal and paste the command docker pull ubuntu.

00:05:38 It's going to do it using the default tag latest and it's going to take some time to pull it.

00:05:44 As you can see, it's working.

00:05:46 Docker initially checks if there are any images with that name on our machine.

00:05:51 If not, it searches for the Docker Hub, finds the image, and automatically installs it on our machine.

00:05:58 Now, if we go back to Docker Desktop, we'll immediately see an Ubuntu image right here under Images.

00:06:05 To confirm that we actually installed a whole different operating system, we can run a command that executes the image.

00:06:13 Do you know how that process is called?

00:06:15 Creating a container.

00:06:17 So let's run docker run-it for interactive and then ubuntu and press enter.

00:06:27 After you run this command, head over to docker desktop.

00:06:30 And if you go to containers, you'll see a new container based off of the ubuntu image.

00:06:36 Coming back to our terminal, you'll see something different.

00:06:39 If you've ever tried Ubuntu before, you'll notice that this terminal looks exactly like the Ubuntu command line.

00:06:46 Let's test out some of the commands.

00:06:49 ls for list.

00:06:51 We have cd home to move to our home directory.

00:06:55 mkdir, which is going to create a new directory called hello.

00:06:59 We can once again ls.

00:07:01 cd into hello to navigate to it.

00:07:04 We can create a new hello-ubuntu.txt.

00:07:10 We can LS to check it out if it's there.

00:07:13 And it is.

00:07:14 We have just used different Ubuntu commands right here within our terminal.

00:07:19 Amazing, isn't it?

00:07:21 We are running an entirely different operating system simply by executing a Docker image within a Docker container.

00:07:29 For now, let's kill this terminal by pressing this trash icon and navigate back to our Docker desktop.

00:07:36 Now, a bigger question awaits.

00:07:38 How do we create our own Docker images?