Assignment For 25 Oct 2021 – Docker Session
Assignment# 1 – What is Docker and Container? Define in 15 points with example image
is a tool which manages Containers and it provides industry a const efficient , time efficient and quality infrastructure. Docker is a utility built on top of kernel which is responsible to allocate resources from main system which is used by Containers. Dockers basically talks to kernel as per User requests and creates below core resources from kernel Namespace which will be used by containers:-
Docker Architecture is as below :—–
HumanRequest -> Docker Client + Docker Server + ContainerD + KernelD
Above red highlighted part is of Docker
Container is an utility which initializes PID Tree FileSystem, MNT FileSystem , NET FileSystem and attached these to USER FileSystem.
There can be multiple copy of containers in system which is managed by Docker. Container’s main components are as below
ROOT FyleSystem + USER FileSystem + APP FIleSystem
Assignment# 2 – What is the differnece between docker pause and unpuase?
Docker pause keeps entry alive in database of and only holds the live execution whatever was happening inside the docker, and making it unpause will resumes processes from where it was paused.
That means inside docker current state of container is still maintained when it is paused … like PID , MNT, NET etc. And these are not released. Once unpaused, same entries are utilized again.
Assignment# 3 – What is the differnece between docker stop and kill?
UNlike docker pause, when docker stop happens , resources like MNT, PID Tree , NET are released . Memory is free to be utilized by others. Only thing is it still mainatans the entry of User for which it was created. So if next time docker is started again, User mapping will be same although other resources are re-initialized like NET, MNT, and PID Tree.
Kill docker means we are removing any trace of any entry related to that docker hence this time no user mapping will be maintained. All will be erased.