Why You Can’t Treat OCI Images Like Full Operating System Containers

In the world of modern virtualization, it’s easy to assume that all “containers” are interchangeable. After all, an OCI image, a Docker image, and an LXC container all sound like variations of the same thing. But the truth is far more nuanced—and misunderstanding the differences can lead to broken workloads, confusing compatibility issues, and containers that simply weren’t designed to act like full operating system environments.

Let’s break down why OCI images are not suitable as drop-in replacements for OS containers, and why Docker-style application containers often behave unpredictably when you try to run them on an LXC host.

OCI Images Are Purpose-Built for Applications — Not Operating Systems

OCI (Open Container Initiative) images follow a strict specification designed around the idea of application-first containers. Everything—from their filesystem layout to the process model—is engineered to launch a single process, not an entire Linux environment.

Here’s why that matters:

1. They Lack a Full Init System

Typical operating system containers (like LXC) use:

• a proper init system
• full system services
• background daemons
• clean process supervision

OCI images aren’t built for that. They’re meant to run one application. If you attempt to treat them like a real OS, you quickly find:

• no working /sbin/init
• no service manager
• no multi-process orchestration

They simply weren’t built for multiprocess OS-level behavior.

2. Many System Utilities Are Missing

Because OCI images are optimized for size, they strip out:

• system binaries
• kernel-facing utilities
• core Linux tools
• package managers (in many cases)

Try to enter the container expecting a fully functional OS and you may find that:

• bash isn’t there
• systemctl doesn’t work
• networking tools are missing
• /proc or /sys behavior differs

Not ideal when you’re expecting a normal user environment.

3. Minimal, Immutable, and Often “Headless” by Design

OCI containers follow the “immutable application” philosophy:

• ship the app
• ship only what the app needs
• never act like a full guest OS

This clashes entirely with LXC’s model of running a full Linux system with:

• shells
• interactive access
• package updates
• background services

Trying to shoehorn an OCI image into an OS container environment usually results in a broken or limited system.

Why Docker Containers Don’t Always Work on LXC Hosts

You can sometimes run Docker containers inside LXC, or even import OCI images as LXC templates using experimental features—but it is not guaranteed to work. And when it fails, it fails in ways that are often confusing.

Here’s why:

1. Differing Container Philosophies

Docker / OCI = Application-first, single process, immutable
LXC = Machine-first, full OS, multi-process

These two worlds have different assumptions:

• Docker expects to be PID 1 and manage the sole process.
• LXC expects a full Linux hierarchy with system services.

When those assumptions collide, weird things happen.

2. Syscall and Kernel Isolation Differences

Docker containers depend on:

• seccomp profiles
• AppArmor profiles
• cgroup configurations

LXC uses:

• a different init process
• different namespace behavior
• different cgroup layering

Some Docker images depend on Docker-specific syscalls or permissions that LXC does not grant. Result:

• the app won’t start
• it starts but behaves unpredictably
• it runs but you cannot access a shell or debug it

3. Some Containers Will Run — But You Can’t “Enter” Them

This is one of the most common LXC/OCI pain points.

A Docker image might run its main process fine, but:

• no shell exists
• no init system exists
• no access method allows you to interact
• the file structure is barebones

So the app works, but the underlying environment is inaccessible.

This is a problem for VPS-style hosting or any environment where you expect users to “get inside the container.”

4. The Filesystem Structure Doesn’t Match an OS

LXC expects:

• /bin
• /sbin
• /usr
• /etc
• standard FHS layout

OCI images often have:

• compressed layers
• busybox-only environments
• non-standard paths

Mixing the two leads to compatibility issues that are nearly impossible to debug.

LXC and OCI Serve Two Completely Different Purposes

The bottom line:

LXC = full operating system container

Perfect for:

• VPS hosting
• virtual environments
• multiprocess workloads
• running OS-level services
• replacing VMs with containerization

OCI / Docker = application container

Perfect for:

• microservices
• single-application deployments
• CI/CD pipelines
• immutable packaged apps

They are both powerful—but they are not interchangeable.

Why This Matters for Hosting Providers and Developers

If you're building a platform around:

• LXC virtualization
• container VPS hosting
• Proxmox or Incus
• full Linux OS environments

…then using OCI images will cause:

• missing components
• broken shells
• failed services
• unpredictable behavior
• unusable user environments

This is why LXC templates must be built as full OS images, not just imported from Docker Hub.

OCI containers were never meant to be “mini virtual machines.”

Conclusion: Use the Right Tool for the Job

OCI images and LXC containers both have their place in the container ecosystem—but they solve different problems. Trying to use OCI images as full OS environments is like trying to use a motorcycle engine to power a car: same general idea, completely different design, guaranteed problems.

If you want a proper operating system container:

• use LXC images
• use Incus images
• or build full rootfs templates

If you want lightweight, single-process application deployment:

• use Docker
• use OCI runtimes
• use Kubernetes

Understanding the difference saves you hours of debugging and gives your users the experience they expect from a fully functional container VPS.