What are the main OS kernel services used by Docker ?

1. Namespaces 
Namespaces forms important part in Linux, allows running processes with same name under one namespace
Docker utilizes namespaces feature of linux.

ADVANTAGES IN DOCKER IMPLEMENTATION

Namespace services used by Docker : PID, MNT, IPC, UTS, NET

• PID : does process isolation
• NET : manages network interfaces
  
• IPC : manages inter-process communication
  
• MNT : manages mount-points
• UTS : isolates kernel
  

2. Control groups
It restricts resource access to a group of processes.

ADVANTAGES IN DOCKER IMPLEMENTATION

• Multiple containers can have their own set of resources
• Limit the resources for specific container
• Prioritization : can allocate larger CPU/Disk share to specific container

 3. Union file system (UFS)
Storage system which allows files/dirs to form a single cohesive file system.
UFS are fast and lightweight.
Docker uses different variants of UFS :  AUFS, btrfs, vfs, DeviceMapper

ADVANTAGES IN DOCKER IMPLEMENTATION

• Every small change in original image is stored as a separate LAYER on the top of existing image
• Users can have access to different versions of images
  (pulls only incremental changes instead of full images)
• Easy / flexible / quick access