Getting Started

This repository is a sample application to start with a Docker container.

The application is based on the application using NodeJs. Before you can run the application, you need to get the application source code onto your machine. 1- Clone the repository using the following command:

git clone https://github.com/didourebai/workshop1.git

2- View the contents of the cloned repository. You should see the following files and sub-directories.

  ├── getting-started-app/
  │ ├── package.json
  │ ├── README.md
  │ ├── spec/
  │ ├── src/
  │ └── yarn.lock

Build the app's image

To build the image, you'll need to use a Dockerfile. A Dockerfile is simply a text-based file with no file extension that contains a script of instructions. Docker uses this script to build a container image.

In the getting-started-app directory, the same location as the package.json file, create a file named Dockerfile. You can use the following commands to create a Dockerfile based on your operating system.

In the terminal, run the following commands.

Make sure you're in the getting-started-app directory. Replace /path/to/getting-started-app with the path to your getting-started-app directory.
```
 cd workshop1
```
Create an empty file named Dockerfile.
```
 code Dockerfile
```
In the Windows Command Prompt, run the following commands.
```
 cd workshop1
```
Create an empty file named Dockerfile.
```
 type nul > Dockerfile
```
In PowerShell, run the following commands.
```
 cd workshop1
```
Create an empty file named Dockerfile.
```
New-Item -Path . -Name Dockerfile -ItemType File
```

Using a text editor or code editor, add the following contents to the Dockerfile:

# syntax=docker/dockerfile:1

FROM node:18-alpine
WORKDIR /app
COPY . .
RUN yarn install --production
CMD ["node", "src/index.js"]
EXPOSE 3000

Build the image using the following commands:

Build the image.
```
 docker build -t getting-started .
```
The docker build command uses the Dockerfile to build a new image. You might have noticed that Docker downloaded a lot of "layers". This is because you instructed the builder that you wanted to start from the node:18-alpine image. But, since you didn't have that on your machine, Docker needed to download the image.

After Docker downloaded the image, the instructions from the Dockerfile are copied into your application and used yarn to install your application's dependencies. The CMD directive specifies the default command to run when starting a container from this image.

Finally, the -t flag tags your image. Think of this as a human-readable name for the final image. Since you named the image getting-started, you can refer to that image when you run a container.

The . at the end of the docker build command tells Docker that it should look for the Dockerfile in the current directory.

Start an app container

Now that you have an image, you can run the application in a container using the docker run command.

Run your container using the docker run command and specify the name of the image you just created:
```
 docker run -dp 127.0.0.1:3000:3000 getting-started
```
The -d flag (short for --detach) runs the container in the background. This means that Docker starts your container and returns you to the terminal prompt. You can verify that a container is running by viewing it in Docker Dashboard under Containers, or by running docker ps in the terminal.

The -p flag (short for --publish) creates a port mapping between the host and the container. The -p flag takes a string value in the format of HOST: CONTAINER, where HOST is the address on the host, and CONTAINER is the port on the container. The command publishes the container's port 3000 to 127.0.0.1:3000 (localhost:3000) on the host. Without the port mapping, you wouldn't be able to access the application from the host.
After a few seconds, open your web browser to http://localhost:3000. You should see your app.
Add an item or two and see that it works as expected. You can mark items as complete and remove them. Your frontend is successfully storing items in the backend.

At this point, you have a running to-do list manager with a few items.

If you take a quick look at your containers, you should see at least one container running using the getting-started image and on port 3000. You can use the CLI or Docker Desktop's graphical interface to see your containers.

Run the following docker ps command in a terminal to list your containers.

 docker ps

Output similar to the following should appear.

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                      NAMES
df784548666d        getting-started     "docker-entry point.s…"   2 minutes ago       Up 2 minutes        127.0.0.1:3000->3000/tcp   priceless_mcclintock

In Docker Desktop, select the Containers tab to see a list of your containers.