docker an application

Docker containers provide a way to package an application with all its dependencies making it easier for applications to be developed, shipped, and ran. Here is a simple, step-by-step guide on how to dockerize an application.

Step 1: Install Docker

The first thing to do is to install Docker on your computer. Docker offers detailed installation instructions for Windows, Mac, and various Linux distributions on their website. Be sure to download the correct version for your operating system, install it, and check the installation by opening a new command line or terminal window and typing docker --version.

Step 2: Create a Dockerfile

To dockerize an application, you need to create a Dockerfile. This is a text document that contains all the commands you would normally execute manually in order to build a Docker image. In your project’s root directory, create a new file named Dockerfile with no extension.

Step 3: Specify the Base Image

In the Dockerfile, you’ll need to specify the base image that your application will run on. This could be an image of Ubuntu, Alpine, or any other system. You’d usually choose an image that contains just enough to run your application. The FROM command is used to specify the base image.

FROM node:10-alpine

Step 4: Copy Your Application Files

The next step is to copy your application files into the Docker image. You accomplish this with the COPY command.

COPY . /app

Step 5: Expose the Required Port

Your application probably listens on a specific port. You need to tell Docker which port this is so it can be accessible. Use the EXPOSE command for this.

EXPOSE 8080

Step 6: Specify the Launch Command

Finally, specify the command that launches your app. For a Node.js app, this might be npm start, for example.

CMD ["npm", "start"]

Step 7: Build the Docker Image

With your Dockerfile completed, you can now build the Docker image. From the terminal, navigate to your project directory (the same directory as your Dockerfile) and run the docker build command, followed by -t and the name you want to give your Docker image.

docker build -t your-docker-image-name .

Step 8: Run Your Dockerized Application

Finally, you can run your dockerized application with the docker run command. Specify the name of your Docker image and the port you wish to map to your application’s port.

docker run -p 80:8080 -d your-docker-image-name

By following these steps, you have successfully dockerized an application. Now, it will be easier to manage, deploy, and scale your project.