All You Need to Know - Docker

  • Containers: They are sealed, self-contained units of software that have everything needed to run a service.
    What you should know(Viewed)

1. Installing Docker

https://docs.docker.com/get-docker/

2. Using Docker

The Docker flow: Images to containers**

  • Image -> running container
  • docker run docker-name
  • docker ps -> get information on running container
  • image is fixed and does not change

The Docker flow: Containers to images**

  • running container -> image (files are stored in stopped container)
  • docker ps -a all container
  • docker ps -l last container
  • topped container has the software installed in it
  • docker commit -> container to new image
  • Run bash image docker run -ti ubuntu:latest bash
  • create and give images name
  • Run processes in containers
    dc run
    images file exists

Running process in Docker**

  • containers have a min proceed
  • one main process that has name
  • -d run detached container in the background

3. Under the hood

Registries in detail

  • Kernel : controls and organizes storage, programs and so. allocate resources and so on

  • docker manges kernel

  • cgroup to group process together

  • can be client and server

  • docker control socket

docker run -ti --rm -v /var/run/docker.sock docker sh

Docker network

  • Ethernet : move frame on wire of wifi
  • IP layer : move packets on local network
  • routing : forwards packets between networks
  • ports: address particular program on a computer
  • bridges -> virtual network on computer
  • controls the ethenes layer
  • docker builds bridges to create virtual network
  • Routing -> moving packets
  • create fireball rule moves between network
docker run -ti --rm --net=host --privileged=true ubuntu bash

apt-get update 
apt-get install iptables

Exposing port is essentially port forwarding

Process in Docker**

  • process init 1-> to many process
  • shell -> runs other process -> continuer vanishes
    Intro to orchestration
-> docker run -ti --rm --name qasim ubuntu bash 
-> docker inspect --format '{{.State.Pid}}' qasim
 3134

-> docker run -ti --rm --privileged=true --pid=host ubuntu bash
root@e63d21be00c6:/# kill 3134

root@99fb3caf034e:/# exit?

storage in docker**

  • actual storage
  • forms in logical groups
  • filesystem : which file belongs where
  • COWS!!! -> copy on write
  • base image -> write stuff container sees it with changes no change to the image
  • like a file system layer on the image !!! COW COPY ON WRITE
  • managing cows
    • layers -> splits them to gzip files and then puts them on container
    • containers are indigent of storage engine
    • some have limited layers
  • get the right mount order correct

save abd load docker images**

  1. save imaged locally
    docker save
  2. load Images
    load images