You’ve spent the past few weeks working on a new feature for your company’s e-commerce platform, and after testing it on your local machine with no issues, you’re excited to push it to the production environment. However, as soon as the code is deployed, customers begin reporting that the feature is not working. Despite not being able to replicate the issue on your local machine, you eventually realize that the problem is due to missing dependencies in the production environment. Now you have to work late into the night to fix the issue…
The scenario we just described can be a frustrating experience, but the good news is that containerization has been helping solve this problem since almost a decade ago.
In this post, we’ll be diving into the world of containerization and understanding what it is and how it can make your life as a software developer much easier. We’ll start by explaining what exactly a container is, how they come to be, we will compare containers to virtual machines, and then we’ll look at the basics of Docker, the most popular containerization platform. By the end of this post, you’ll have a solid foundation for understanding how containers can help you in your software development journey.
What exactly are containers?
Containers are a way of packaging and distributing software applications, along with all their dependencies, in a single, isolated unit. This unit is called a container image, and it can be run on any system that supports the container technology, regardless of the underlying operating system and hardware.
Containers provide a consistent and reproducible environment for applications, ensuring that they run the same way regardless of the environment they’re in. This makes it easy to move applications from development to testing to production without having to worry about compatibility issues.
Containers are isolated from each other and from the host system, meaning that each container runs its own operating system and has its own file system. This provides strong application isolation, allowing multiple containers to run on the same system without interfering with each other.
Containers are designed to be lightweight and fast, and they use significantly fewer resources than traditional virtual machines. This makes it possible to run many containers on a single system, which is ideal for scaling applications horizontally and increasing the density of your infrastructure.
A Brief list of Benefits
- Portability. Containers allow you to run an application on any machine with the same environment, eliminating the need for extensive testing and reducing compatibility issues. This is particularly useful when deploying applications to different environments, such as from development to production.
- Scalability. Containers are lightweight and can be easily duplicated, making it easier to scale applications to meet increasing demand. This is especially important in today’s fast-paced technological landscape where applications can experience sudden spikes in traffic.
- Isolation. Containers provide isolated environments for each application, reducing the risk of conflicts and making it easier to maintain security. This is critical in today’s cybersecurity landscape where attacks are becoming more sophisticated and frequent.
- Speed. Containers are quick to start and stop, which speeds up development and deployment processes. This is important for organizations that need to quickly respond to changing market conditions or customer demands.
- Cost Savings. By using containers, you can reduce the need for physical hardware, which can lower costs and improve efficiency. This is especially valuable in today’s economic climate where companies are looking for ways to reduce expenses and increase profitability.
A bit of history
Unix operating systems introduced the concept of chroot in the 1970s, which was a technique used to isolate processes from the rest of the system. Chroot provided a way to run multiple applications on a single machine without them interfering with each other, and this was the beginning of the history of containers, a concept that has been around for decades.
As technology advanced, the concept of containerization continued to evolve. The introduction of Solaris Containers (also known as Zones) in the late 1990s added support for full system isolation and resource management, further expanding the capabilities of containers. In 2005, OpenVZ was introduced, bringing containers to Linux operating systems and providing even more advanced isolation and resource management features.
LXC (Linux Containers) followed shortly after in 2008, offering a lightweight solution for Linux containerization that was designed to be fast and efficient. These early containerization technologies laid the foundation for the containers that we know today, paving the way for the introduction of Docker in 2013.
Docker revolutionized the containerization landscape by making it easier for developers to package and distribute their applications. The simple and intuitive interface provided by Docker allowed developers to focus on their applications, rather than the underlying infrastructure, leading to the widespread adoption of containers in the software development industry.
This sounds like VMs!
Containers and Virtual Machines are both technologies that provide isolated environments for applications. However, they differ in several key ways.
Virtual Machines (VMs) emulate a complete operating system, including the hardware and software stack. Each virtual machine runs its own instance of an operating system and has its own virtualized hardware. This means that VMs are completely isolated from each other and from the host system, and each VM can run different applications and operating systems.
However, VMs are resource-intensive, as each virtual machine requires its own operating system, virtualized hardware, and memory. This can result in slow startup times and a large amount of disk space being consumed. Containers, on the other hand, are much lighter and faster than virtual machines. Containers share the host system’s kernel, and they use the host’s resources, such as CPU and memory, to run their applications. This makes them significantly more efficient and faster to deploy than virtual machines.
Feature | Containers | Virtual Machines |
---|---|---|
Boot-time | Fast | Slow |
Runs on | Host OS | Virtualized OS |
Memory Efficiency | High | Low |
Isolation | Process-Level | Full System |
Deployment | Lightweight and Easy | Heavy and Complex |
Performance | High | Moderate |
Another key difference between containers and virtual machines is that containers use a layered file system. This means that multiple containers can share the same base image, and only the changes made to each container are stored in a separate layer, resulting in smaller images and less disk space being consumed.
For example, let’s say you have a base image of an operating system, and you have three containers running on that image. The first container has an application installed, the second container has a different application installed, and the third container has a database installed. Instead of each container having a complete copy of the operating system and all applications, each container only stores the changes made to the base image. In this case, the first container would store the changes made to the base image to install the application, the second container would store the changes made to the base image to install the different application, and the third container would store the changes made to the base image to install the database.
Additionally, as the base image is shared, it’s easier to update and maintain the containers, as only the changes need to be managed, rather than the entire operating system and applications.
For an understanding of the Union File System, you may want to visit this resource: terriblecode – How Docker Images Work: Union File Systems for Dummies
If you want to delve deeper, consider reading this article.: Deep Dive into Docker Internals - Union Filesystem | Martin Heinz | Personal Website & Blog
Docker: The Popular Guy!
It’s not about being the first to do something, but being the first to do it well.
Docker is the most commonly utilized container platform and has become the preferred choice for containerization. Since its launch in 2013, its ease of use and versatility have made it incredibly popular.
Docker makes it simple to package, distribute, and run applications in containers. The creation and sharing of images can be done through public or private repositories, enabling smooth distribution of applications across various environments.
Docker operates with a client-server architecture, where the Docker client communicates with the Docker daemon. The Docker client and daemon can either run on the same system or separate systems, providing easy management of containers in a distributed setup. Docker has numerous tools and features to aid developers in creating, managing, and deploying containers, such as a command-line interface, API, and web-based UI. Additionally, it has a robust third-party tool and plugin ecosystem, making integration with other tools and services seamless.
Let’s set up your container (Docker) environment!
Getting started with Docker is easy, but you’ll need to install the Docker Engine and the Docker CLI on your local machine. The installation process is different depending on the operating system you’re using, so I recommend following the official Docker documentation for your specific operating system.
Once you’ve installed Docker, you’re ready to start using it! The Docker CLI is the main tool you’ll use to interact with Docker, so it’s important to understand the basic commands. You can use the docker run
command to launch a container, the docker images
command to list all the images on your machine, and the docker ps
command to list all the containers that are currently running.
In this post, we’ve introduced you to the world of containerization and how containers can make your life as a software developer much easier. We’ve compared containers to virtual machines and looked at the basics of Docker, the most popular container platform. By the end of this post, you should have a solid foundation for understanding how containers can help you in your software development journey.
In the next post, we’ll be diving deeper into the world of Docker and looking at how to build and manage Docker images. Stay tuned!
Leave a Reply