Docker in Software Development: What is Docker? Since its launch in 2013, Docker has become a common tool in DevOps and cloud computing fields. It provides a way to rapidly create, test, and deploy software applications through containers with ease.
In this post, I’ll break down what Docker is, how and why to use Docker in software development, how it’s different from virtual machines (why use containers over virtual machines), and some resources to help you learn Docker and related technologies.
By the end of this post, you’ll have a good understanding of Docker and know where you can go to learn more about it.
What Is Docker?
Docker definition: Docker is a suite of open-source platform-as-a-service (PaaS) tools often used in cloud computing.
These tools allow you to create, deploy, and run applications, using something known as “containers.”
Did you know: Docker’s logo is a whale that looks like a cargo/container ship!
So what are containers? Containers let developers packing up all of the elements of an application/program known as “dependencies” (e.g., host, code, operating system, libraries, system tools, settings) and deploy it as one single container or package.
Everything that’s needed to run the application is self-contained. In other words, the application will work anywhere — from a developer’s computer to a physical data center to a staging/QA environment to production.
Using containers is particularly important for professionals who use Continuous Integration/Continuous Deployment (CI/CD) DevOps methodology. In CI/CD, software developers put their code into a shared repository early and frequently, making it faster for teams to deploy code.
What Is the Difference Between Docker and Virtual Machines?
Containers and virtual machines (VMs) are similar in some ways (they pack up all of the dependencies of an application into one), but the way they work is different.
- Containers visualize the operating system (OS), while hypervisor-based VMs visualize the hardware.
- Containers allow you to virtualize many apps on a single, shared OS instance, while VMs virtualize apps on multiple OS instances. (Visual of this below.)
Due to this reason, VMs often take up more memory and storage than containers. Moreover, VMs are harder to run across public clouds, private clouds, and data centers.
In short, VM is more resource-intensive than containers.
Why Use Docker?
Today developers make use of Docker for their day-to-day activities. If you’re going to create applications, why use Docker to do it?
Docker takes away repetitive, mundane configuration tasks and is used throughout the development lifecycle for fast, easy and portable application development – desktop and cloud. Docker’s comprehensive end to end platform includes UIs, CLIs, APIs and security that are engineered to work together across the entire application delivery lifecycle.
https://www.docker.com/
Benefits of the Docker platform for software development
Developers and teams who use Docker can enjoy benefits like these:
- Code gets shipped faster
- Portable and efficient
- Ability to run anywhere
- Makes the development process more agile and responsive
- Smaller footprint than virtual machines
- Standardizes environments from development to production
- Better security since every application is isolated
- Easy to modify and update programs
- Automated container creation
How to Use Docker
To create a Docker-containerized application, you start by creating a Dockerfile, which is a text file with instructions/commands that are required to build a Docker image. The Dockerfile includes info like programming languages, file locations, dependencies, what the container will do once it runs, etc. It automates the process of Docker image creation.
You then create a Docker image using the Docker “build” utility based on the Dockerfile. A Docker image is a file that contains a set of instructions for what components of the application the container will run and how. It contains executable application source code and the dependencies the application needs in order to run.
When you run the Docker image using the “run” utility, it then launches an instance of the container.
Where to learn Docker?
Docker Official Blog and Docs
Docker’s official blog covers news and other important feeds on Docker.
For any guides, documentations and tutorials, refer to Docker documentation here.
