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System Containers vs. Application Containers: A delve into the world of LXD

DockerLXD

Introduction

Docker has been a household name in the world of containerization; however, it is not the only container technology available. LXD is a system-container manager that offers a powerful alternative with its unique features and capabilities.
In this article we’ll explore what LXD containers are and how they differ from Docker, providing insights into when and why you might choose one over the other.

What Are LXD Containers?

It’s a common misconception that LXD competes directly with Docker. In reality, these are two completely different technologies designed for different purposes.

LXD (pronounced lex-dee, not el-ex-dee 😉) is a container management tool that provides a “virtual machine-like” experience using Linux Containers (LXC). Unlike Docker, which focuses on application containers, LXD provides full-system containers, making it ideal when you need a complete OS environment.

So, What Are System Containers?

Application containers such as Docker are built to package and host a single application process. They are typically ephemeral: you create, delete, and replace them with ease, but you can’t modify the running application and keep it updated without rebuilding the image.

System-level containers, on the other hand, provide a full operating system environment inside a container. They behave like lightweight virtual machines and can run any workload you’d normally run on a VM or physical server.

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Key traits of system containers:

  • Long-lasting, suitable for hosting several applications in one container.
  • You can install, remove, or update applications on the fly—no need to rebuild images.

Both system and application containers share a kernel with the host OS for isolation, but their purpose and lifecycle differ significantly.

Key Features of LXD

  • System Containers – Operate like virtual machines, complete with their own init system.
  • Image Management – Supports a wide range of Linux distributions; easy importing, exporting, and custom images.
  • Network & Storage Flexibility – Advanced networking (bridged, routed, macvlan) and storage backends like ZFS, Btrfs, and LVM.
  • Security & Isolation – Uses AppArmor, seccomp, and user namespaces to ensure strong isolation.

When to Use LXD Over Docker

Choose LXD when you need:

  • Full-System Environments – Multiple applications and services within a complete Linux OS.
  • Advanced Networking & Storage – Sophisticated network topologies or custom storage backends.
  • Resource Management – Fine-grained control over CPU, memory, and disk resources.
  • Long-Running Applications – Ability to patch or update apps on the fly without destroying containers.

Conclusion

Both LXD and Docker are powerful containerization tools, each with unique strengths and ideal use cases.
Understanding the difference between LXD’s system containers and Docker’s application containers helps you choose the right tool for your needs—whether that’s complex multi-application environments or lightweight microservices.

To get hands-on with LXD, try the official tutorial:
First Steps with LXD

tags: #LXD #Docker #Containerization #CloudEngineering #DevOps #SystemContainers #ApplicationContainers #TechComparison #LinuxContainers #CloudComputing