Docker Fundamentals
Docker VS Virtual Machine
Containers package code and dependencies together , multiple containers share the kernel with each other , each running as isolated process in user space.Containers takes up less memory than VMs and start up instantly.
VM are abstraction of physical hardware , the hypervisor allow multiple VMs with different OS to run on same machine .Each VM include full copy of OS,It take more memory than container and slow to boot.
The one big difference between containers and VMs is that containers share the host system’s kernel with other containers.
Docker Host
Docker is an open-source project based on Linux containers. It uses Linux Kernel features like namespaces and control groups to create containers on top of an operating system.
The container runtime is responsible for the whole life cycle of a container. It pulls a container image (which is the template for a container) from a registry if necessary, creates a container from that image, initializes and runs the container, and eventually stops and removes the container from the system when asked.