TL;DR: I was three hours deep into a Docker networking debug session — containers couldn't reach each other, docker network inspect was giving me nothing useful — and I had this uncomfortable realization: I was treating Docker like magic. I knew the commands. 📖 Reading time: ~41 min What's in this article Why I Built This (And Why You Should Too) The Four Linux Primitives Docker is Built On Step 1 — Isolating a Process With Namespaces Step 2 — Building a Minimal Root Filesystem With debootstrap\ Step 3 — Pivoting the Root With chroot\ (and Why pivot\_root\ Is Better) Step 4 — Limiting Resources With cgroups v2 Step 5 — Network Isolation With a veth Pair Putting It All Together — A ~80 Line Shell Script That Actually Works Why I Built This (And Why You Should Too) I was three hours deep into a Docker networking debug session — containers couldn't reach each other, docker network inspect was giving me nothing useful — and I had this uncomfortable realization: I was treating Docker like magic.…