Recognizing the Distinctions Between Virtual Machines and Docker

Introduction to Docker and Virtual Machines

Virtual machines (VMs) and Docker are widely used tools for application deployment, although they function fundamentally differently. How Docker can offer a full filesystem, segregated networking, and other functionality without the expense usually associated with virtual machines (VMs) confounds a lot of engineers.

The purpose of this article is to elucidate the differences between Docker and conventional virtual machines, elucidating why Docker is frequently regarded as more lightweight and simpler to deploy software on. We'll explore the underlying technology as well as the useful advantages of deploying Docker in real-world settings.

Exploring Dockerfile and Vagrantfile

Initially, we showed how to make a Dockerfile for Node.js application deployment in the examples that were given. The FROM command is used to define the base image in the Dockerfile, which is an official Node.js runtime in this case. The WORKDIR command is used to set the working directory within the container. This command guarantees that all commands that follow will be run in the directory that is supplied. The application code and package.json files are moved inside the container using the COPY command. The required dependencies are then installed inside the container by using the RUN command. Lastly, the CMD command specifies the command to launch the program when the container starts. We expose the port the application runs on using this command.

Using Ubuntu 20.04 as the base box, the configuration for the Vagrantfile example begins with the config.vm.box command. The config.vm.network command is used to configure the network settings. It forwards port 8080 from the host to port 80 on the guest virtual machine (VM), enabling external access to the VM's services. A shell script that installs Apache2 and updates the package list is launched by the 8 command, which also provisioned the virtual machine with the required software. In contrast to the containerized environment that Docker provides, these instructions demonstrate the basic procedures to setup a virtual machine (VM).

# Use an official Node.js runtime as a parent image
FROM node:14

# Set the working directory inside the container
WORKDIR /usr/src/app

# Copy package.json and package-lock.json to the container
COPY package*.json ./

# Install the application dependencies inside the container
RUN npm install

# Copy the rest of the application code to the container
COPY . .

# Expose the port the app runs on
EXPOSE 8080

# Define the command to run the app
CMD ["node", "app.js"]

# -*- mode: ruby -*-
# vi: set ft=ruby :

# All Vagrant configuration is done below. The "2" in Vagrant.configure
# configures the configuration version (we support older styles for
# backwards compatibility). Please don't change it unless you know what
# you're doing.
Vagrant.configure("2") do |config|
  # Use Ubuntu 20.04 as the base box
  config.vm.box = "ubuntu/focal64"

  # Forward port 8080 on the host to port 80 on the guest
  config.vm.network "forwarded_port", guest: 80, host: 8080

  # Provision the VM with a shell script
  config.vm.provision "shell", inline: <<-SHELL
    sudo apt-get update
    sudo apt-get install -y apache2
  SHELL
end

Comprehending Virtual Machines and Docker

The way that Docker and virtual machines (VMs) use system resources is one of their main differences. Virtual machines (VMs) operate on hypervisors, which simulate hardware and enable the simultaneous use of different operating systems on a host computer. To do this, every virtual machine (VM) needs to have its own set of binaries, libraries, and a complete guest operating system. This not only uses a lot of system resources, but it also makes deployment and maintenance more complicated and large-scale overall.

On the other hand, Docker makes use of containerization technology, which permits the sharing of an operating system kernel among several containers. In user space, every container operates as a separate process. Because they don't require the full OS to boot up, containers are lighter and start up faster than virtual machines (VMs). By using a layered filesystem, where each container has its own filesystem layer on top of a base image, Docker is able to accomplish filesystem isolation. Namespaces are used to manage network isolation, which enables Docker to create isolated networking environments for every container without the overhead of virtual machines.

Comparing Virtual Machines and Docker

The main distinction between virtual machines and Docker is how well they use resources and deploy them. Higher resource usage results from the whole guest operating system and hypervisor that virtual machines run. On the other hand, Docker containers provide a lighter and more flexible solution by sharing the host OS kernel. With the use of networking namespaces and a layered filesystem, Docker creates separated environments that enable it to function similarly to virtual machines (VMs) without the overhead. This improves the consistency, efficiency, and manageability of software deployment to Docker images across different production settings.