What are the main components of the Linux kernel that form the basis of containerization in Docker?

Docker containerization works based on several key Linux kernel components:

• Namespaces — isolate processes by creating separate namespaces for PID, network, filesystem mounts, users, and others. This allows containers to operate as if they are on separate machines.

• Control Groups (cgroups) — limit and control resource usage (CPU, memory, disk, network) for groups of processes, ensuring resource management for containers.

• Union File Systems (OverlayFS, AUFS, etc.) — enable the creation of layered filesystems where containers can use a shared base image and add their own changes without duplicating data.

• Capabilities and Security Modules (AppArmor, SELinux) — provide security and restrict process rights inside containers.

These mechanisms together ensure isolation, resource management, and security, which allows Docker to efficiently run containers.