This document provides an overview of containerization and Docker. It covers prerequisites, traditional application deployment challenges, container components like namespaces and cgroups, major Docker concepts like images and containers, common Docker commands, building Dockerfiles, and Docker workflows and best practices. Hands-on exercises are included to build and run containers.

2. ● Basics of container and Docker
● Major Docker components
● Starting learning basic docker commands
● Hands-on labs and exercises
● Quiz
Course outline

3. Prerequisites
● Basic knowledge of how OS works, no need
to be expert
● At least 1 virtual machine

4. Traditional application deployment

5. A bit of scale makes a bit of scare

12. Containers under the hood

23. cgroups - Wikipedia
cgroups (abbreviated from control groups) is a Linux kernel feature that limits,
accounts for and isolates the resource usage (CPU, memory, disk I/O, network,
etc.) of a collection of processes.
Engineers at Google (primarily Paul Menage and Rohit Seth) started the work
on this feature in 2006, under the name "process containers".[1] In late 2007
the nomenclature changed to "control groups" due to the confusion caused by
multiple meanings of the term "container" in the Linux kernel context, and
control-group functionality merged into kernel version 2.6.24.[2] Since then,
developers have added many new features and controllers, such as support for
kernfs,[3] firewalling,[4] and unified hierarchy.[5]

26. Quiz - Containers
What are the benefits of using container
instead of VM?
● No need for hypervisor
● No need for operating system
● No physical hardware
● No need for priveleged user
● No. It’s uselles.

27. Quiz - Containers
What are the benefits of using container
instead of VM?
● No need for hypervisor
● No need for operating system
● No physical hardware
● No need for priveleged user
● No. It’s uselles.

28. I create process with PID=1234 in container. What PID will
be on host OS?
a. the same as in container: PID=1234
b. on host there will be PID=4321 that maps to PID=1234
in container
c. it wont be created in container. Actually container
creates it on host.
d. there will be no pid on host. PID=1234 is the child
process in container
Quiz - Containers

29. I create process with PID=1234 in container. What PID will
be on host OS?
a. the same as in container: PID=1234
b. on host there will be PID=4321 that maps to PID=1234
in container
c. it wont be created in container. Actually container
creates it on host.
d. there will be no pid on host. PID=1234 is the child
process in container
Quiz - Containers

30. What are the main components of namespaces?
a. uts, ipc, pid, network, user, mount
b. user, pid, mount, filesystem, application, io
c. pid, os, hardware, user, internet, filesystem
d. mount, hardware, network, user, pid, cgroup
Quiz - Containers

31. What are the main components of namespaces?
a. uts, ipc, pid, network, user, mount
b. user, pid, mount, filesystem, application, io
c. pid, os, hardware, user, internet, filesystem
d. mount, hardware, network, user, pid, cgroup
Quiz - Containers

32. Quiz - Containers
What should i do to run application with unprivileged user in
container?
a. change the owner to current user and run it
b. login as sudo and run the application
c. enter the container and run it
d. login as sudo then chown the application then run it

33. Quiz - Containers
What should i do to run application with unprivileged user in
container?
a. change the owner to current user and run it
b. login as sudo and run the application
c. enter the container and run it
d. login as sudo then chown the application then run it

39. Major Docker components

41. In short: write once, really run anywhere

42. Docker images and containers

43. pull the image from docker cloud servers

44. Images repository - Dockerhub

45. Installing Docker engine
1. Open https://docs.docker.com/installation/
2. Find the name of your host operating system
from the list
3. Follow the instructions

46. Linux: Add current user to docker group
sudo gpasswd -a <user_name> docker

47. Mac OS: set env variables for boot2docker
boot2docker up
export DOCKER_HOST=tcp://192.168.59.103:2376
export DOCKER_CERT_PATH=<cert path>
export DOCKER_TLS_VERIFY=1
or
$(boot2docker shellinit)
Get ip of boot2docker: boot2docker ip
Check version of docker: docker version

48. Windows: maybe like on MacOS...but didnt try
boot2docker up
set DOCKER_HOST=tcp://192.168.59.103:2376
set DOCKER_CERT_PATH=<cert path>
set DOCKER_TLS_VERIFY=1
or
boot2docker shellinit
Get ip of boot2docker: boot2docker ip
Check version of docker: docker version

49. Let docker say: Hello World!
docker run hello-world

50. Now let’s get into the container
1) docker pull centos – fetch centos image from repository
2) docker run centos – run fetched centos image within container
3) docker ps - list the running containers
4) docker ps -a - list all the containers (running + not running)
5) docker exec - to execute the command inside container
6) docker attach - get into the container
7) exit from container quits the container
8) Ctrl+P and Ctrl+Q leaves the running container
9) docker inspect <container_id> - show info about running container

51. Lab: Run required container
IOS/Android developers:
1) docker run -d –p 8080:8080 jenkins
2) Open http://<docker_host>:8080 in your browser and create build plan in
jenkins
Service developers:
1) docker run -it --rm williamyeh/scala
2) Write hello world in scala
TIP: docker --help is you cheat sheet

52. Quiz - Docker
What is the difference between images and containers?
a. containers consist of binary files, images consist of user app files
b. containers run only once, whereas images run multiple times
c. containers pulled from dockerhub, whereas images stores locally
d. images consist of instructions and user files, whereas containers
only runtime environment for user process

53. Quiz - Docker
What is the difference between images and containers?
a. containers consist of binary files, images consist of user app files
b. containers run only once, whereas images run multiple times
c. containers pulled from dockerhub, whereas images stores locally
d. images consist of instructions and user files, whereas containers
only runtime environment for user process

54. Quiz - Docker
What will be the result of the following instructions?
docker run -it my-image /bin/bash # let’s say it returns ID 123...
echo “Sample text” | cat > SampleText.txt
exit
docker cp 123:/root/SampleText.txt ./
a. will copy SampleText.txt to current directory
b. will copy data from the current directory to /root/SampleText.txt inside container
c. prints to screen Sample text and copies SampleText.txt to current directory on docker host
d. does nothing. Terminates with error

55. Quiz - Docker
What will be the result of the following instructions?
docker run -it my-image /bin/bash # let’s say it returns ID 123...
echo “Sample text” | cat > SampleText.txt
exit
docker cp 123:/root/SampleText.txt ./
a. will copy SampleText.txt to current directory
b. will copy data from the current directory to /root/SampleText.txt inside container
c. prints to screen Sample text and copies SampleText.txt to current directory on docker host
d. does nothing. Terminates with error

56. Quiz - Docker
What will be the result of the following instructions?
docker run -d my-image /bin/bash echo “Sample text” | cat > SampleText.txt
# let’s say returns id 123...
docker run -d my-image /bin/bash “ping 8.8.8.8”
docker cp 123:/root/SampleText.txt ./
a. will copy SampleText.txt to current directory
b. will copy data from the current directory to /root/SampleText.txt inside container
c. prints to screen Sample text and copies SampleText.txt to current directory on docker host
d. does nothing. Terminates with error

57. Quiz - Docker
What will be the result of the following instructions?
docker run -d my-image /bin/bash echo “Sample text” | cat > SampleText.txt
# let’s say returns id 123...
docker run -d my-image /bin/bash “ping 8.8.8.8”
docker cp 123:/root/SampleText.txt ./
a. will copy SampleText.txt to current directory
b. will copy data from the current directory to /root/SampleText.txt inside container
c. prints to screen Sample text and copies SampleText.txt to current directory on docker host
d. does nothing. Terminates with error

58. Writing own Dockerfile
FROM ubuntu:latest
MAINTAINTER <name surname>
FROM ubuntu:latest
RUN apt-get update
RUN apt-get install -y nginx
CMD ["nginx", "-g", "daemon off;"]

59. Docker Workflow 1
1) Download file from curl -L -O http://github.com/atbaker/flask-example/archive/master.zip
2) Unzip master.zip
3) run python flask-example.py
Build as docker:
FROM python:2-onbuild
EXPOSE 8000
CMD [“gunicorn”, “-c”, “gunicorn_config.py”, “flask-example:app”]

60. Docker Workflow 2
Download file from curl -L -O http://github.com/atbaker/django-example/archive/master.zip
Build as docker:
FROM python:2.7-onbuild
EXPOSE 8000
CMD [“gunicorn”, “-c”, “gunicorn_config.py”, “--chdr”, “django-example”, “wsgi:application”]
docker run --name postgres -d postgres:9.3
docker run --name memcached -d atbaker/memcached-verbose
docker run --name django -d -p 8000:8000 --link postgres:db --link memcached:cache django-example
docker run --name django --link postgres:db --link memcached:cache django-example python django/example/manage.py migrate

61. Docker workflow 2 with Docker-Compose
django:
build: .
links:
- postgres:db
- memcached:cache
ports:
- “8000:80”
postgres:
image:postgres:9.3
memcached:
image:atbaker/memcached-verbose

62. Useful resources
https://docs.docker.com/ - official docs from Docker
https://docs.docker.com/compose/ - official docs about Docker
Compose
https://docs.docker.com/docker/introduction/understanding-docker/ -
Docker architecture
https://linuxcontainers.org/ - WiKi about Linux Containers (LXC)
https://lwn.net/Articles/531114/ - Linux namespaces overview
https://lwn.net/Articles/532748/ - Linux PID namespaces