Docker Tutorial: Build a Container Filesystem From Scratch (chroot, RootFS & Namespaces)
Most engineers run containers every day but never ask: where does the filesystem actually come from?
In this video, you'll build a container filesystem from scratch using raw Linux commands no Docker, no container runtime. Just the Linux kernel doing its thing.
You'll learn:
🗂️ How Linux Processes See the Filesystem
→ Every process starts at / — the root of the entire Linux file tree
→ Changing what / points to changes everything a process can see
🔧 Build a Custom RootFS From Scratch
→ Create the directory structure (bin, lib64, etc, proc, usr)
→ Copy binaries + shared libraries using ldd and awk
→ The exact same structure Docker uses inside every container
🔒 chroot: The Filesystem Isolation Primitive
→ How chroot locks a process into a specific root directory
→ Why chroot alone isn't enough — and what's still shared
📦 Combine chroot + Namespaces: A Real Container
→ Use unshare to create PID, Mount, UTS & Net namespaces
→ Add chroot — now you have filesystem AND process isolation
→ Your process sees PID 1, its own hostname, its own filesystem
🐳 How Docker & Kubernetes Automate This
→ Docker doesn't do magic — it automates every step you just did
→ Inspect a real nginx container image with Podman
→ Extract the image layers — it's the same filesystem you built manually
📌 This is part of the Kernel Primitives for Containers series, where we
build containers from scratch using raw Linux internals, one kernel
primitive at a time.
📌 Watch the full series → • Linux Kernel Primitives for Containers
▬▬▬▬▬▬▬ Timestamps ▬▬▬▬▬▬▬
00:00 - Intro: The Missing Piece After Namespaces
00:33 - How Linux Processes See the Filesystem
02:05 - Building a Custom RootFS From Scratch
09:54 - How Container Runtimes Use RootFS
10:45 - Combining chroot + Namespaces: A Real Container
13:44 - How Docker & Kubernetes Automate This
14:25 - Inspecting a Real Docker Image Filesystem
16:31 - Outro & Next: OverlayFS Deep Dive
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#linux #docker #containers #chroot #rootfs #kubernetes #devops #linuxkernel #containerization #k8s #dockertutorials #linuxtutorials