Download - ABCs of Docker
● Basics of container and Docker● Major Docker components● Starting learning basic docker commands● Hands-on labs and exercises● Quiz
Course outline
Prerequisites
● Basic knowledge of how OS works, no need to be expert
● At least 1 virtual machine
Traditional application deployment
A bit of scale makes a bit of scare
Containers under the hood
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]
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.
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.
I create process with PID=1234 in container. What PID will be on host OS?a. the same as in container: PID=1234b. on host there will be PID=4321 that maps to PID=1234
in containerc. 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
I create process with PID=1234 in container. What PID will be on host OS?a. the same as in container: PID=1234b. on host there will be PID=4321 that maps to PID=1234
in containerc. 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
What are the main components of namespaces?a. uts, ipc, pid, network, user, mountb. user, pid, mount, filesystem, application, ioc. pid, os, hardware, user, internet, filesystemd. mount, hardware, network, user, pid, cgroup
Quiz - Containers
What are the main components of namespaces?a. uts, ipc, pid, network, user, mountb. user, pid, mount, filesystem, application, ioc. pid, os, hardware, user, internet, filesystemd. mount, hardware, network, user, pid, cgroup
Quiz - Containers
Quiz - Containers
What should i do to run application with unprivileged user in container?a. change the owner to current user and run itb. login as sudo and run the applicationc. enter the container and run itd. login as sudo then chown the application then run it
Quiz - Containers
What should i do to run application with unprivileged user in container?a. change the owner to current user and run itb. login as sudo and run the applicationc. enter the container and run itd. login as sudo then chown the application then run it
Major Docker components
In short: write once, really run anywhere
Docker images and containers
pull the image from docker cloud servers
Images repository - Dockerhub
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
Linux: Add current user to docker group
sudo gpasswd -a <user_name> docker
Mac OS: set env variables for boot2docker
boot2docker up
export DOCKER_HOST=tcp://192.168.59.103:2376export DOCKER_CERT_PATH=<cert path>export DOCKER_TLS_VERIFY=1or $(boot2docker shellinit)
Get ip of boot2docker: boot2docker ipCheck version of docker: docker version
Windows: maybe like on MacOS...but didnt try
boot2docker up
set DOCKER_HOST=tcp://192.168.59.103:2376set DOCKER_CERT_PATH=<cert path>set DOCKER_TLS_VERIFY=1or boot2docker shellinit
Get ip of boot2docker: boot2docker ipCheck version of docker: docker version
Let docker say: Hello World!
docker run hello-world
Now let’s get into the container
1) docker pull centos – fetch centos image from repository2) docker run centos – run fetched centos image within container3) docker ps - list the running containers4) docker ps -a - list all the containers (running + not running)5) docker exec - to execute the command inside container6) docker attach - get into the container7) exit from container quits the container8) Ctrl+P and Ctrl+Q leaves the running container9) docker inspect <container_id> - show info about running container
Lab: Run required container
IOS/Android developers:1) docker run -d –p 8080:8080 jenkins2) Open http://<docker_host>:8080 in your browser and create build plan in
jenkins
Service developers:3) docker run -it --rm williamyeh/scala4) Write hello world in scala
TIP: docker --help is you cheat sheet
Quiz - Docker
What is the difference between images and containers?a. containers consist of binary files, images consist of user app filesb. containers run only once, whereas images run multiple timesc. containers pulled from dockerhub, whereas images stores locallyd. images consist of instructions and user files, whereas containers
only runtime environment for user process
Quiz - Docker
What is the difference between images and containers?a. containers consist of binary files, images consist of user app filesb. containers run only once, whereas images run multiple timesc. containers pulled from dockerhub, whereas images stores locallyd. images consist of instructions and user files, whereas containers
only runtime environment for user process
Quiz - DockerWhat 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.txtexitdocker cp 123:/root/SampleText.txt ./
a. will copy SampleText.txt to current directoryb. will copy data from the current directory to /root/SampleText.txt inside containerc. prints to screen Sample text and copies SampleText.txt to current directory on docker hostd. does nothing. Terminates with error
Quiz - DockerWhat 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.txtexitdocker cp 123:/root/SampleText.txt ./
a. will copy SampleText.txt to current directoryb. will copy data from the current directory to /root/SampleText.txt inside containerc. prints to screen Sample text and copies SampleText.txt to current directory on docker hostd. does nothing. Terminates with error
Quiz - DockerWhat 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 directoryb. will copy data from the current directory to /root/SampleText.txt inside containerc. prints to screen Sample text and copies SampleText.txt to current directory on docker hostd. does nothing. Terminates with error
Quiz - DockerWhat 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 directoryb. will copy data from the current directory to /root/SampleText.txt inside containerc. prints to screen Sample text and copies SampleText.txt to current directory on docker hostd. does nothing. Terminates with error
Writing own Dockerfile
FROM ubuntu:latestMAINTAINTER <name surname>FROM ubuntu:latestRUN apt-get updateRUN apt-get install -y nginxCMD ["nginx", "-g", "daemon off;"]
Docker Workflow 1
1) Download file from curl -L -O http://github.com/atbaker/flask-example/archive/master.zip2) Unzip master.zip3) run python flask-example.py
Build as docker:
FROM python:2-onbuildEXPOSE 8000CMD [“gunicorn”, “-c”, “gunicorn_config.py”, “flask-example:app”]
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-onbuildEXPOSE 8000CMD [“gunicorn”, “-c”, “gunicorn_config.py”, “--chdr”, “django-example”, “wsgi:application”]
docker run --name postgres -d postgres:9.3docker run --name memcached -d atbaker/memcached-verbosedocker run --name django -d -p 8000:8000 --link postgres:db --link memcached:cache django-exampledocker run --name django --link postgres:db --link memcached:cache django-example python django/example/manage.py migrate
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
Useful resources
https://docs.docker.com/ - official docs from Dockerhttps://docs.docker.com/compose/ - official docs about Docker Composehttps://docs.docker.com/docker/introduction/understanding-docker/ - Docker architecturehttps://linuxcontainers.org/ - WiKi about Linux Containers (LXC)https://lwn.net/Articles/531114/ - Linux namespaces overviewhttps://lwn.net/Articles/532748/ - Linux PID namespaces