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What is containerization?

Containerization encapsulates an application and its dependencies into a container image, facilitating consistent execution across any host operating system supporting a container engine.

6 min read

Containerization encapsulates an application and its dependencies into a container image, facilitating consistent execution across any host operating system supporting a container engine. 

The historical roots of containerization trace back to the concept of virtual machines (VMs), which allowed developers to run multiple operating systems on a single physical server. However, VMs encapsulate not just the application and its dependencies but also an entire guest operating system, leading to significant overhead and reduced server efficiency. The inception of containerization marked a departure from this model, focusing on lightweight, portable, and efficient deployment units.

The more widely companies use containers, the more likely they are to call security their top challenge with containers.

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In other words, containerization's rise to prominence is not merely a result of technological advancement; it’s also a response to the growing complexity of modern applications and the need for scalable, reliable deployment methods. This process allows developers to achieve uniformity in application performance and behavior across diverse environments, addressing the "it works on my machine" syndrome.

The shift towards microservices architecture has also significantly transformed app development and operation paradigms. Containers, synonymous with microservices, offer a modular approach, as opposed to the monolithic structure associated with VMs. This fosters more agile, resilient, and scalable application ecosystems.

This blog post will cover containerization's benefits, technical details, popular technologies, and container security, empowering you to create future-proof containerized environments.

Benefits of containerization

The adoption of containerization brings a multitude of benefits for software development and deployment:

  • Improved resource utilization: Unlike virtual machines, containers share the host's kernel, reducing overhead and enhancing server efficiency. Additionally, this approach minimizes hardware costs and boosts application scalability.

  • Increased developer productivity: Containerized applications are encapsulated with their environment into a single container image, promoting consistency across development, testing, and production. Uniformity fosters a DevOps culture, streamlining the development life cycle through continuous integration and delivery (CI/CD).

  • Simplified configuration and testing: Utilizing configuration files for container settings keeps applications performing consistently across different environments, mitigating bugs and discrepancies.

  • Increased security and fault tolerance: Containers operate independently, providing fault isolation that secures applications from affecting each other. Isolation is vital for the stability and reliability of complex systems applications and protects the host from any malicious code contained within a compromised container.

When we explore the technical workings of containerization in the next section, these advantages will become even more apparent, highlighting why containerization has become an indispensable tool.

How containerization works

Containerization starts by creating a container image: a compact, self-contained executable package that encompasses all the essentials for the software's operation, such as the code, libraries, and configuration.

Container images are built from a Dockerfile or similar configuration files that specify the application's environment. Once created, these images are stored in a registry, such as Docker Hub, where they can be downloaded and run on any system with a container engine installed. This engine, such as Docker or Podman, is responsible for container life cycle management, including running, stopping, and managing container instances.

Container engines play a crucial role in the host operating system, leveraging the kernel's features (such as namespaces and cgroups) to isolate the container's processes and manage resources. Each container has its own user spaces, file system, and network stack, allowing multiple containers to run simultaneously on a single host without interference.

The workings of containerization, from image creation to orchestration, underscore its efficiency and flexibility:

Figure 1: Containerization overview (Source: Docker)

By abstracting away the underlying hardware and operating systems, containerization allows developers to focus on building and deploying applications without worrying about the environment where the application will run. 

Containerization vs. VMs

As we’ve seen, virtual machines emulate an entire hardware system for each VM, running a complete guest operating system on top of the host's physical hardware. This approach provides strong isolation but at the cost of significant overhead because each VM requires its own OS, leading to increased resource consumption and slower startup times. Additionally, this setup demands ongoing maintenance, including patch management and system updates, further adding to the operational burden.

Containerization, however, shares the host's kernel but isolates the application's processes and dependencies into containers. The containerization model significantly reduces overhead because containers are much lighter than VMs, leading to faster startup times and more efficient use of system resources. Containers provide process-level isolation, which, while not as strong as the hardware-level isolation of VMs, is sufficient for most applications and adds the benefit of server efficiency.

Deciding between containerization and virtualization hinges on your particular requirements. Containerization is ideal for microservices architectures, cloud-native applications, and environments where server efficiency and rapid scaling are priorities. VMs are better suited for applications requiring complete OS isolation, legacy applications not designed for containers, or situations where the overhead of a full VM is not a concern.

Popular containerization technologies

The container technology landscape is rich and varied, with solutions designed to cater to different aspects of the container life cycle—from image creation and management to orchestration and security:

Docker

Docker, which is now considered a synonym for containerization, provides an extensive platform that streamlines the creation, distribution, and execution of applications within containers. The Docker engine is at the heart of Docker's platform, enabling containers to be packaged and run consistently across different environments.

Docker benefits from a robust community and ecosystem. It offers extensive documentation, a vast library of container images on Docker Hub, and community support, making it an ideal starting point for those new to containerization.

Figure 2: Docker Hub (Source: Docker)

LXC (Linux Containers)

LXC (Linux Containers) is a more traditional containerization technology that predates Docker. The key difference between LXC and Docker lies in their approach to containerization. LXC is more like a lightweight VM, offering a complete Linux system within each container, whereas Docker focuses on application containerization, making it easier to package and ship applications:

Figure 3: LXC, Docker, and VM architecture (Source: Oracle Forums)

LXC is preferable for scenarios requiring full Linux system containers rather than just application containers. It offers a solution closer to virtual machines but with the efficiency of containers. LXC maintains a dedicated community and documentation, though it is smaller than Docker's expansive ecosystem.

Windows Server containers

Windows Server containers offer containerization technology integrated with the Windows Server operating system. This enables Windows-based applications to be containerized and managed similarly to Linux-based containers. While Docker focuses on Linux containers, it also supports Windows containers, providing a cross-platform solution for containerization. Windows Server containers, however, are specifically optimized for the Windows environment and provide a path to modernizing legacy Windows applications through containerization.

Figure 4: Windows containers in Windows Admin Center (Source: Microsoft)

As we’ve seen, the choice of containerization technology depends on specific project requirements, including the target operating system, the nature of the application, and the desired level of isolation and efficiency. As the container technology landscape continues to evolve, staying informed about these technologies and their capabilities is crucial for leveraging the full benefits of containerization.

Containerization and security

Because containerization has become increasingly prevalent in software development and deployment, understanding and addressing its security implications is paramount. Though containers offer numerous benefits, they also introduce specific security challenges that must be managed to protect applications and data effectively.

Common security risks in containerized environments include:

  • Image vulnerabilities: Containers are only as secure as their base images, and vulnerable images can introduce security risks to the environment. 

  • Misconfigurations: Incorrectly configured containers or container orchestration tools can expose applications to security threats.

  • Runtime security: Containers share the host's kernel, which can lead to potential escape vulnerabilities if a container is compromised. Container Runtime Security Explained ->

  • Network security: Containers often communicate with each other and with external services, necessitating robust network security policies to prevent unauthorized access.

To mitigate these risks, several strategies for securing containerized applications can be employed:

  • Secure the build pipeline: Implement security checks and vulnerability scanning within the CI/CD pipeline to ensure container images are secure before deployment.

  • Use trusted base images: Only use container images from trusted registries and maintain them by installing patches and updates to reduce the risk of vulnerabilities.

  • Leverage isolation and segmentation: Use network policies and other mechanisms to isolate containers from each other and segment them from the broader network, limiting the potential spread of malicious activity.

  • Implement continuous security assessments: Continuously scan container images for vulnerabilities and monitor running containers for suspicious activity, employing tools designed for container environments.

Conclusion

Containerization has fundamentally reshaped software development and deployment, offering a pathway to more efficient, scalable, and consistent application delivery. As we look to the future, container technology continues to evolve, promising even greater advancements in orchestration, security, and performance optimization. The ongoing development of this ecosystem suggests a future where containerization both simplifies and also accelerates the pace of software innovation.

When it comes to navigating the complexities of containerized deployments, Wiz is a pivotal ally. With our unified cloud security platform, we offer prevention, detection, and response capabilities that empower you to build and run secure, efficient applications in the cloud. 

Wiz's approach to container and Kubernetes security allows teams to rapidly build containerized applications without compromising on risk. Our platform's comprehensive coverage—from managing vulnerabilities, secrets, and misconfigurations across clouds and workloads to continuous monitoring for suspicious activity—ensures that containerized environments are holistically secured from build-time to runtime. For developers and organizations ready to embrace or advance their use of containerization, explore Wiz today and unlock the tools and insights necessary for success.

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