Docker

DOCKER
Over view session
DMITRY BOLGAROV

AGENDA
• What is Docker?
• Layers, Images, Containers
• Containers vs Virtual Machines
• What is Docker’s architecture?
• Docker Engine
• Docker Registry
• Kinematic, Docker UI
• Q&A
Use Insert > Header Footer to Edit Footer Text 2

WHAT IS DOCKER ?
Main things:
• Container virtualization
• Build, ship and run applications as containers
• Build once, run in many places
• Isolated and content agnostic
Docker is a platform for developing, shipping and running applications using
container virtualization technology

INTRODUCING CONTAINERS
• Each guest instance is called a container
• Each container has its own
- Root filesystem
- Processes
- Memory
- Devices
- Network ports
Docker container based virtualization uses the kernel on the host’s operating
system to run multiple guest instances

LAYERS, IMAGES, CONTAINERS

CONTAINERS VS VIRTUAL MACHINE
Containers are isolated,
but share OS and, where
appropriate, bins/libraries
Container
As result is significantly faster
deployment, much less
overhead, easier migration,
faster restart

DOCKER CONTAINER LIFECYCLE
The Life of a Container
– Conception
• BUILD an Image from a Dockerfile
– Birth
• RUN (create+start) a container
– Reproduction
• COMMIT (persist) a container to a new image
• RUN a new container from an image
– Stop
• STOP a running container
– Start
• START a stopped container
– Death
• RM (delete) a stopped container
– Extinction
• RMI a container image (delete image)

WHAT IS DOCKER’S ARCHITECTURE?
Docker uses a client-server
architecture. The Docker client
talks to the Docker daemon,
which does the heavy lifting of
building, running, and
distributing your Docker
containers. The Docker client
and daemon can run on the
same system, or you can
connect a Docker client to a
remote Docker daemon. The
Docker client and daemon
communicate via sockets or
through a REST API.

INSTALL DOCKER ON UBUNTU
Update your APT package index
sudo apt-get update
Install Docker
sudo apt-get install docker-engine
Start the Docker daemon
sudo service docker start
Verify docker is installed correctly
sudo docker run hello-world
This command downloads a test image and runs it in a container.
When the container runs, it prints an informational message. Then, it exits.

DOCKER RUN HELLO-WORLD
docker@Docker:~$ sudo docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
c04b14da8d14: Pull complete
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.

RUN AN INTERACTIVE CONTAINER
Let’s specify a new command to run in the container.
$ docker run -t -i ubuntu /bin/bash
root@af8bae53bdd3:/#
In this example:
•docker run runs a container.
•ubuntu is the image you would like to run.
•-t flag assigns a pseudo-tty or terminal inside the new container.
•-i flag allows you to make an interactive connection by grabbing the standard in (STDIN) of the container.
•/bin/bash launches a Bash shell inside our container.

START A DAEMONIZED HELLO WORLD
Let’s create a container that runs as a daemon.
$ docker run -d ubuntu /bin/sh -c "while true; do echo hello world; sleep 1; done“
$
In this example:
•docker run runs the container.
•-d flag runs the container in the background (to daemonize it).
•ubuntu is the image you would like to run.
Finally, we specify a command to run:
/bin/sh -c "while true; do echo hello world; sleep 1; done"

USEFUL COMMANDS
The docker ps command queries the Docker daemon for information about all the containers it knows about
$ docker@Docker:~$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f26c8e7074dc ubuntu "/bin/sh -c 'while tr" About an hour ago Up About an hour gloomy_ritchie
docker@Docker:~$
docker logs looks inside the container
docker logs <containerID>
docker@Docker:~$ docker logs -ft f26c8e7074dc
2016-09-23T10:00:21.350379711Z hello world
2016-09-23T10:00:22.351196918Z hello world
^C
.

USEFUL COMMANDS
The docker exec command runs a new command in a running container.
docker@Docker:~$ docker exec -it f26c8e7074dc /bin/bash
root@f26c8e7074dc:/#
docker images - The command lists all the images on your local system
docker@Docker:~$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu latest 45bc58500fa3 3 days ago 126.9 MB
hello-world latest c54a2cc56cbb 11 weeks ago 1.848 kB
docker cp - Copy files/folders between a container and the local filesystem
Usage: docker cp [OPTIONS] CONTAINER:SRC_PATH DEST_PATH
docker cp [OPTIONS] SRC_PATH|- CONTAINER:DEST_PATH
.

EXAMPLE FILESYSTEM AND PORT MAPPINGS
$ docker run -it --rm -p 8888:8080 -v /path/to/agent.jar:/ajent.jar -e JAVA_OPTS="-javaagent:/agent.jar" tomcat:8.0.29-jre8
-p 8888:8080. This binds port 8080 of the container to port 8888 on 127.0.0.1 of the host machine.
The -v flag mounts the current working directory into the container.
-e, --env take an environment variable and value
--rm - destroy container
.

LINK TWO CONTAINERS
docker@Docker:~$ docker run -d --name dbpost -h dbserver postgres
docker@Docker:~$ docker ps
162718c3a123 postgres "/docker-entrypoint.s" 8 seconds ago Up 7 seconds 5432/tcp dbpost
docker@Docker:~$ docker run -it --name website -h ubuntuWEB --link dbpost:db ubuntu:14.04 bash
root@ubuntuWEB:/# cat /etc/hosts
127.0.0.1 localhost
172.17.0.2 db dbserver dbpost
172.17.0.3 ubuntuWEB
root@ubuntuWEB:/#
docker@Docker:~$ docker ps
4952944b362c ubuntu:14.04 "bash" 21 seconds ago Up 21 seconds website
162718c3a123 postgres "/docker-entrypoint.s" About a minute ago Up About a minute 5432/tcp dbpost
docker@Docker:~$
16
Another

DOCKER STATS
The docker stats command returns a live data stream for running container
Running docker stats on all running containers
$ docker stats
CONTAINER CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O
1285939c1fd3 0.07% 796 KiB / 64 MiB 1.21% 788 B / 648 B 3.568 MB / 512 KB
9c76f7834ae2 0.07% 2.746 MiB / 64 MiB 4.29% 1.266 KB / 648 B 12.4 MB / 0 B
d1ea048f04e4 0.03% 4.583 MiB / 64 MiB 6.30% 2.854 KB / 648 B 27.7 MB / 0 B
.

DOCKERFILE
• Create Dockerfile with following content:
FROM docker/whalesay:latest
RUN apt-get -y update && apt-get install -y fortunes
CMD /usr/games/fortune -a | cowsay
• Build image
$ docker build -t docker-whale .
• Check that image was created
$docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
docker-whale latest cafebf45a032 55 seconds ago 274.9 MB
$ docker run docker-whale
_____________________________
/ List each check separately by bank
number. /
----------------------------------------------

## .
## ## ## ==
## ## ## ## ===
/""""""""""""""""___/ ===
~~~ {~~ ~~~~ ~~~ ~~~~ ~~ ~ / ===- ~~~
______ o __/
__/
__________/

DOCKERFILE ANOTHER EXAMPLE
FROM ubuntu:trusty
ENTRYPOINT ["/bin/ping","-c","3"]
CMD ["localhost"]
Let's build and run this image without any additional docker run arguments:
$ docker run ping
PING localhost (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.025 ms
64 bytes from localhost (127.0.0.1): icmp_seq=2 ttl=64 time=0.038 m
And with some host as argument
$ docker run ping docker.io
PING docker.io (162.242.195.84) 56(84) bytes of data.
64 bytes from 162.242.195.84: icmp_seq=1 ttl=61 time=76.7 ms
64 bytes from 162.242.195.84: icmp_seq=2 ttl=61 time=81.5 ms
19
Another

DOCKERFILE FORMAT
FROM <image>:<tag> # base image
MAINTAINER <name> #Author@email.for.example
ENV <key> <value> # or ENV <key>=<value>
ADD <src> <dest> # ADD hom* /mydir/ # adds all files starting with "hom"
COPY <src> <dest> #COPY hom?.txt /mydir/ # ? is replaced with any single character, e.g., "home.txt"
WORKDIR /path/to/workdir
VOLUME ["/data"] # creates a mount point with the specified name and marks it as holding externally mounted volumes from native host
EXPOSE <port> [<port>...] # The EXPOSE instruction informs Docker that the container listens on the specified network ports at runtime
RUN <command> # or RUN ["executable", "param1", "param2"]
CMD ["executable","param1","param2"] #(exec form, this is the preferred form)
CMD ["param1","param2"] #(as default parameters to ENTRYPOINT)
CMD command param1 param2 #(shell form)
#The main purpose of a CMD is to provide defaults for an executing container.
#There can only be one CMD instruction in a Dockerfile.
#If you list more than one CMD then only the last CMD will take effect.
ENTRYPOINT ["executable", "param1", "param2"] # An ENTRYPOINT allows you to configure a container that will run as an executable.
20
Another

TYPES OF REGISTRY
Docker Hub
Docker Registry
Docker Trusted
Registry
Docker Registry is an open source application
dedicated to the storage and distribution of
your Docker images.
Docker Hub is a public Docker registry which
serves a huge collection of existing images and
allows you to contribute your own.
Docker Trusted Registry (DTR) is the enterprise-
grade image storage solution from Docker.

DEPLOYING A DOCKER REGISTRY SERVER
Start your registry:
docker run -d -p 5000:5000 --restart=always --name OurRegistry registry:2
You can now use it with docker.
Get any image from the hub and tag it to point to your registry:
docker pull ubuntu && docker tag ubuntu <our_host>:5000/ubuntu
then push it to your registry:
docker push <our_host>:5000/ubuntu
then pull it back from your registry:
docker pull <our_host>:5000/ubuntu
To stop and remove your registry, you would:
docker stop OurRegistry && docker rm -v OurRegistry

HOW WE CAN USE IT ?
Run container and do some changes:
docker@DockerTemplate:~$ docker run -it --name MyUbuntu -h MyUbuntu ubuntu /bin/bash
root@MyUbuntu:/# echo "Hi There" > /1.txt
root@MyUbuntu:/# cat /1.txt
Hi There
root@MyUbuntu:/#
Stop container and tag it to point to your registry :
docker stop MyUbuntu
docker tag ubuntu <our_host>:5000/Ubuntu
docker commit -m "My changes" MyUbuntu <our_host>:5000/ubuntu
Commit changes and push them to your registry:
docker push <our_host>:5000/ubuntu

DOCKER HUB AUTO BUILD
Docker Hub detects commits to source repository and builds the image

DOCKER HUB AUTO BUILD

WHERE I CAN RUN IT ?
Windows 10 Pro - Docker for Windows
(uses Hyper-V)
Win 7,8, 8.1 - Docker Toolbox
(uses Oracle Virtual Box)
OS X 10.10.3 or newer - Docker for Mac
(uses HyperKit)
OS X 10.8 or newer - Docker toolbox
(uses Oracle Virtual Box)
Ubuntu 12.04, 13.04 et al
RHEL 6.5+
openSUSE 12.3+
Centos 6+
etc.

DOCKER UI
docker run -d -p 9000:9000 --privileged -v /var/run/docker.sock:/var/run/docker.sock --name DockerUI uifd/ui-for-docker
Open your browser to
http://<dockerd host ip>:9000

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