Namespace

What a container actually is on an Ubuntu VM — three problems that VMs and containers each solve, the runtime stack from dockerd and kubelet down to runC, why runC vanishes and containerd-shim stays as the parent, the six namespaces and one cgroup directory seen through /proc.

Inside the Linux kernel on an Ubuntu VM — a Python server under strace, the same socket seen from ss and /proc, why FD 4 comes back four times, interfaces as doors and lo as a mirror, veth pairs and a bridge built by hand, network namespaces as rooms, and nsenter into a Docker container’s room.