Here’s something we all know: modern applications are becoming increasingly complex, which only makes things like updating code, deploying new features, and streamlining DevOps workflows more difficult as literally everything gets bigger and more complex.
Fortunately, when executed correctly, the use of containerization can make things easier and less complex.
Let’s walk through what containerization means these days, how it works, and how it can benefit your workloads and application development.
What is containerization?
A container is essentially an isolated, portable, computing environment that contains everything required to run an application, e.g.: necessary executables, binary code, libraries, dependencies, and configuration files. A single container can run anything from a small microservice to software processes and large apps. Containerization refers to the software development process of bundling an app’s code with all the files and libraries needed to run on any infrastructure.
With containerization, you gain the ability to consistently deploy an application in any computing environment, whether on-premises or cloud-based. This avoids the need to install application versions that match operating systems. For instance, you would typically need to install a Windows version of a software package to run it on a device with a Windows operating system. Containerization enables you to sidestep this scenario, as the container is a single software package that can run on any device or operating system.
How does containerization work?
As we know, containers are self-sufficient software packages that can run unimpeded on any type of machine or device.
To achieve this, developers must first create and deploy container images—read-only, unalterable files containing the aspects required to run a containerized app. This is done by using tools based on the Open Container Initiative (OCI) image specification—an open-source group that offers a standardized format for making container images.
What are the layers of containerization?
Container images are the top layer in a containerized system that are geneally comprised of the following layers:
- Infrastructure - the hardware layer, i.e., the computer or bare metal server that actually runs the containerized application.
- Operating system - the operating system can be either on-prem or in the cloud. Linux remains a go-to choice for on-premise computers, while cloud service providers such as AWS EC2 are popular choices for running containerized apps in the cloud.
- Container engine - the software that creates containers based on the container images. This program functions as an intermediary between the operating system and the containers by providing and managing the resources required by the application and keeping other containers independent of each other.
- Application and dependencies - the actual code and any other files required to run are at the top level of the container’s architecture, including configuration files and library dependencies.
What is container orchestration?
As you can probably imagine, managing the massive number of containerized microservices can be quite the task (as in, virtually impossible).
Fortunately, container orchestration tools like Kubernetes exist. This technology enables the automatic management of containers—including all the microservices and their corresponding containers. Ultimately, containerization orchestration provides developers with scalability for cloud applications in a precise manner while sidestepping those pesky human errors.
(You can learn much, much more about container orchestration here.)
Container technology
The primary component of container architecture is Docker, an open source based on the Linux kernel used for creating containers within an operating system.
By accessing a single operating system kernel, Docker can manage multiple distributed applications that run in their own container. The containers themselves are created from Docker images, which are read-only. However, the Docker still adds a read-write file system to the image-only file system when creating a container. The images can be sourced from Docker Hub, which contains thousands of images readily available for public use. Docker Hub’s library has practically any image you’ll need for your containers and any specific application need.
Once the container has been created, Docker initiates a network interface that communicates the container with the local host. It then adds an IP address to the container and executes the indicated process to execute the application that has been assigned to it.
Containerization use cases
Here are just a few examples of common use cases with containerization:
Cloud migration
Sometimes referred to as “lift-and-shift,” cloud migration is an approach some organizations use to modernize their legacy applications by encapsulating them in containers and redeploying them in modern cloud architectures, thus avoiding the need to rewrite the software’s code.
Enabling microservice architecture
Anyone looking to build cloud applications via microservices will need to utilize containerization to do so since the architecture requires multiple independent software components in order to sustain a functioning application. Every microservice is devoted to a unique function, and cloud-based apps house multiple microservices. Containerization enables developers to use microservices as deployable programs across different platforms.
IoT devices
IoT devices are often constrained to a limited amount of resources for computing, so updating their software manually is often extremely complex. Containerization solves this issue by letting developers deploy IoT applications in an automated manner.
Support for continuous integration and deployment (CI/CD)
Containerization enables a streamlined way to build, test, and deploy from the same container images, which supports CI/CD.
Benefits of containerization
Containerization delivers a wide range of benefits to your DevOps processes in workflows, so let’s cover the most important ones below:
Portability
We’ve touched on this a bit already, but it bears repeating again: containerization enables unrivaled portability. All dependencies are bundled in a container, so you can move your application anywhere without the need to rebuild it for a new environment. Whether you move it to a cloud environment, run it on a virtual machine, or move it to bare metal, it will always be ready to deploy seamlessly.
Efficiency
Containerization is an incredibly efficient method of virtualization and, when configured correctly, boosts overall efficiency by using all available resources while completely minimizing overhead costs. This is due to the isolated nature of containers and the avoidance of interference, which frees up a single host to undertake a variety of functions without missing a beat.
Plus, since containers use the host operating system’s kernel, they eliminate the need for virtualized operating systems and other types of bottlenecks.
Agility
Containers can be rapidly created and deployed to any type of environment, which enables agility in development teams by streamlining workflows. They can be quickly developed and deployed for a wide range of tasks and then automatically shut down when no longer needed. As mentioned earlier, this is where technology such as Kubernetes comes in handy, as it enables developers to automate container management.
Faster delivery
As you probably already know, implementing updates to an app can take even longer when it’s on the larger end of the size spectrum—a fact that often bogs down the delivery process. Containerization sidesteps this problem by compartmentalizing your application. Even the biggest applications can be divided using microservices to segment pieces into different containers.
This approach typically makes the dev process easier to implement changes and deploy the new corresponding code. Isolated parts of the application can be altered without affecting the entire thing. Plus, a containerized model ensures that problems can be fixed at the container level without the need to re-architect and redeploy entire applications.
Improved security
Containerization makes apps more secure thanks to the added layer of security provided by the isolation, which ensures your apps are running within a self-contained environment. If one container is breached or compromised, the other container environments on the host will remain unaffected. This also ensures that the containers and data are isolated from the host OS and retain minimal interaction with compute resources, further securing application deployment.
Faster startup
Isolated environments executed in a single kernel require fewer resources, which results in quick startup times. Containers don’t depend on hypervisor or virtualized operating systems to access computing resources, so your startup times occur in an instant (depending on your application code, of course). This creates a development environment more conducive to frequent updates and upgrades.
More flexibility
Containerization gives developers the flexibility to code in both bare metal and virtual environments. Plus, in the event that you need to retool your environment between the two, your containerized apps are equipped to switch from one to the other. In fact, you can even host some elements on bare metal and deploy separate elements to virtual environments. Bottom line: containerization empowers developers to redefine the available resources at their disposal.
Hold up, are containers really just virtual machines?
You may sometimes see containers confused with virtual machines—that’s understandable, as they both isolate applications and do not require any physical hardware. However, some key differences do exist. Virtual machines (VMs) run in a hypervisor environment and are managed with separate guest operating systems, plus all the related binaries, libraries, and application files, which together occupy a massive amount of system resources. Meanwhile, containers share the same host operating system or kernel of the host with other containers and consume just a fraction of the resources.
Containerization vs. serverless computing
Containerization is also quite different from serverless computing, which involves the cloud vendor completely managing the server infrastructure that powers an application. It also allows applications to be deployed instantly since there are no dependencies. Conversely, as we discussed above, containers are more portable and provide developers with full control of the application's environment.
See how LaunchDarkly works with Kubernetes
LaunchDarky’s feature management platform enables your development teams to rapidly create and manage feature flags when testing code changes in a production environment, giving them a seamless, low-risk way to test changes at a high frequency—and on a large scale with several layers of redundancy. Plus, it’s an ideal solution for attaining fine-grained control over all the features in your application within the context of both container-based and microservices architectures.
Check out how LaunchDarkly works with Kubernetes in the video below.
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