Standardized units for software development, shipment and deployment are packaged by containers. They encapsulate everything an application needs to run, including:

• The code
• Runtime
• Libraries
• System tools

In the broader container ecosystem context, containers provide a consistent and efficient way to manage and deploy applications across various environments.

This ensures the application behaves the same regardless of when it is deployed. This isolation is the essence of containerization, where applications are run in self-contained environments separate from the underlying system.

The transformative aspect of containers lies in their ability to run uniformly across diverse platforms such as:

• Linux
• Windows
• Mac OS
• Virtual machines
• Physical servers

This cross-environment consistency means that an application tested on a developer’s laptop will behave identically when deployed to a public cloud or a private data center. Containers isolate the application code and dependencies, enabling a clear division of duties: developers can concentrate on code writing while IT operations manage deployment.

Containers vs Virtual Machines: Are They the Same?

Containers and VMs each have their strengths and weaknesses. Virtual machine containers share the host machine’s kernel, network interface and file system, making them lightweight and efficient. However, VMs emulate physical hardware and require full operating system instances. Unlike VMs, which emulate physical hardware, containers virtualize at the OS level, resulting in reduced overhead and faster startup times.

However, this efficiency comes at the cost of isolation. Managed by hypervisors, VMs provide stronger isolation as each VM operates with its own OS, memory and other resources. As such,  VMs are a better choice for environments requiring stringent security and control. The following subsections explore the architectures of both containers and VMs for a more in-depth comparison.>

Container Architecture

Container architecture virtualizes the operating system at the user space level, sharing CPU, memory, storage and network resources. The host system’s kernel facilitates this sharing, ensuring minimal overhead.

Virtual Machine Architecture

Virtual machines operate differently. They use a hypervisor to manage multiple VMs on a single physical machine that runs on a host operating system. Each VM has its operating system, memory and resources, which isolates it from other VMs. This approach, while secure, results in higher overhead due to the need for full OS instances. Virtual machine architecture interacts with the container ecosystem by providing a more isolated environment with greater resource consumption than containers.

Containerization encapsulates an application in a container with its operating environment, abstracting the software from the underlying hardware for consistent execution. This involves bundling the application’s code with its necessary files and libraries, ensuring it runs uniformly across various infrastructures. For a more comprehensive understanding, the process of building and running containers will be discussed in the subsequent subsections.

Building Container Images

Building container images starts with a Dockerfile, a script that outlines the instructions for creating the image. This file specifies the operating system, environment variables and other configurations needed to build the Docker image. These images are read-only templates that include all dependencies required to run the application.

Running Containers

Running containers is managed by container runtimes like Docker Engine and containerd. The runtime is responsible for:

• Creating and managing the lifecycle of containers based on the provided images>
• Mounting the image
• Setting up namespaces and control groups for isolation
• Ensuring that containers run independently of the underlying infrastructure

Key Components of Containers

Several key components collaborate to ensure the functionality of containers. These components include the container runtime, container images and system libraries and tools. These components help ensure applications run smoothly and efficiently; they also provide the necessary infrastructure for containerized applications. Each component plays a crucial role in the container ecosystem. 

Container Runtime

The container runtime manages the resources and isolation for containers. It acts as an intermediary between the containers and the operating system, using namespaces to provide isolated environments and control groups (cgroups) to manage resource allocation.

Container Image

A container image is a lightweight, standalone package that includes everything needed to run software. Based on the Open Container Initiative (OCI image specification, these images ensure standardization and consistency. They are stored in registries for easy access and version control.

System Libraries and Tools

System libraries and tools, including code runtime system tools, ensure the application runs as expected across different environments. These necessary binaries and libraries are packaged within the container to maintain functionality and reduce dependency on the host system.

Containers offer a variety of key benefits, such as reduced complexity, cost-effectiveness and enhanced security. They support agile and DevOps practices, enabling faster development, testing and deployment cycles. Let’s explore some of these benefits in detail: portability, efficiency and scalability.

Portability

Portability is one of the most significant advantages of using containers. Containerized applications are built to perform consistently, regardless of the underlying infrastructure. This means that an application running in a container can be easily deployed across various operating systems and hardware platforms without modification.

Portability enables seamless transitions and consistent performance across different environments.

Efficiency

Containers are more efficient than traditional VM environments because they:

• Consume fewer system resources
• Share the host system’s kernel, reducing overhead and improving resource utilization
• Allow multiple containers to run on a single host more effectively

Efficiency allows for better performance and resource management.

Scalability

Containers can be quickly deployed and scaled across multiple servers or cloud environments to handle increased loads.

Container platform solutions make it easy to launch new containers as needed and shut them down when they are no longer required.

Container Orchestration

Container orchestration automates various tasks related to containers, such as:

• Deployment
• Management
• Scaling
• Networking

This streamlines the process and improves efficiency in handling containerized applications. Tools like Kubernetes have become the de facto standard for managing containerized applications, simplifying operations by automating repetitive tasks.

Kubernetes

Kubernetes is an open source platform that automates Linux container operations. It offers features like automated scaling, load balancing, self-healing capabilities and rolling updates.

Kubernetes clusters can run multiple containers organized into pods, making it a powerful tool for managing containerized applications.

Other Orchestration Tools

Besides Kubernetes, other orchestration tools include Docker Swarm and Apache Mesos. Docker Swarm provides simpler container orchestration built into Docker. Apache Mesos supports various architectures and offers high availability and non-disruptive upgrades.

Security is a critical aspect of containerization. Containers introduce several security concerns, including a larger attack surface due to the variety of underlying images. Implementing and maintaining security controls are essential to protect complex containerized environments.

Key considerations include process isolation, network policies and role-based access control (RBAC).

Process Isolation

Process isolation ensures that processes running within a container do not interfere with those in other containers. This is achieved through namespaces, which provide isolated environments for different processes.

Network Policies

Network policies restrict communication paths to only those necessary for the application. In Kubernetes, network policies can control the flow of traffic between pods, enhancing security by limiting unnecessary communication.

Role-Based Access Control (RBAC)

Role-Based Access Control (RBAC) is essential for managing permissions within containerized environments. In Kubernetes, RBAC ensures users have specific access levels based on their roles, following the principle of least privilege. This granular management of permissions minimizes the risk of unauthorized access and helps protect resources. 

Several container technologies have gained popularity due to their unique features and capabilities. Docker, Podman and CRI-O are among the most widely used. Each of these technologies offers different advantages, making them suitable for various use cases.

The specifics of these popular container technologies are examined in detail below.

Docker

Docker’s impact on the container landscape was significant, increasing accessibility and standardization. This revolutionized the way applications are developed and deployed. Linux containers utilize Linux Kernel features, such as namespaces and control groups. These features are employed to create isolated environments for running applications. Docker provides a robust platform for container management and orchestration.

Docker Hub, a cloud-based repository, allows users to store and share their container images. This capability significantly simplifies the process of deploying docker containers and containerized applications.

Podman

Podman is a popular alternative to Docker, offering seamless container management without relying on a daemon. This architecture simplifies container deployment and maintenance, making Podman an attractive option for developers seeking flexibility and control.

CRI-O

CRI-O is a lightweight container runtime designed specifically for Kubernetes. It works with the Kubernetes Container Runtime Interface (CRI) to manage containers, providing a streamlined and efficient runtime environment for Kubernetes clusters.

The rapid evolution of containerization is intersecting with technologies such as AI and IoT. The rise of edge computing creates new opportunities for deploying containerized applications closer to the data source. As the technology matures, the evolution of container standards and regulations is becoming increasingly important, with organizations like the Cloud Native Computing Foundation playing a crucial role in this process. These future trends are explored in further detail below.

Integration with Emerging Technologies

AI workloads are increasingly being containerized to ensure consistency and portability across different environments. Containers facilitate the integration of machine learning models into diverse applications, enabling faster deployment and scalability.

This intersection of container technology with AI and IoT paves the way for innovative solutions and new business models.

Evolution of Standards and Regulations

The adoption of the Open Container Initiative (OCI) standards is growing, ensuring interoperability between different container technologies. Regulatory bodies are beginning to establish guidelines for container security and compliance, influencing how organizations deploy containerized applications.

These evolving standards and regulations are crucial for maintaining the integrity and security of container ecosystems.

SUSE gives you control of your containerized environments through our enterprise-grade container management solution, SUSE Rancher Prime. Our open, flexible approach allows you to innovate freely while benefiting from:

• Comprehensive support for Kubernetes and other container orchestration tools
• Advanced security features to protect your containerized applications
• Seamless integration with various cloud platforms and on-premises environments
• A strong community and extensive resources for continuous learning and development

SUSE's solutions fit seamlessly into the container ecosystem and provide the needed tools and support. SUSE is dedicated to providing you with unparalleled choice and long-term support so you can manage and scale containerized applications effectively. Choosing SUSE means choosing a partner dedicated to helping you harness the full potential of containerization for your business needs. Together, we make choice happen.

Frequently Asked Questions

What are Containers?

Containers encapsulate applications and their dependencies into a standardized unit, ensuring consistent behavior across different environments. They make it easier to deploy and manage applications.

How Do Containers Differ From Virtual Machines?

Containers are more lightweight and efficient because they share the host system's kernel. VMs provide stronger isolation by emulating physical hardware and requiring full operating systems.

What Is The Role Of A Container Runtime?

The role of container runtime is to manage the lifecycle of containers, ensuring they run independently of the underlying infrastructure and other containers.

Why Is Portability A Key Benefit Of Containers?

Portability is a key benefit of containers because it allows them to be deployed across various platforms and environments without modification, ensuring consistent application performance.

What Are Some Popular Container Orchestration Tools?

Some popular container orchestration tools include Kubernetes, Docker Swarm and Apache Mesos, which are known for automating container deployment, management and scaling.