An introduction to Docker, how it fits in with the DevOps landscape, and how to work with containers and images

1. Up and Running
With Docker
Presented by Michelle Liu
https://github.com/anonmily/docker-up-and-running

2. Outline
1. What is Docker?
2. Applications of Docker
3. Terminology: How Docker Works
4. Tools
5. Installation
6. Images
7. Containers
8. Docker Registry
9. Docker Workflow
10. Docker Remote API
11. QA

3. The Deployment Dilemma
• Inter-dependent dependencies
• Inconsistent environments
• Development != Production
• “Works on my machine…”

4. The Deployment Dilemma

5. Lots of dependencies/interactions between services and applications

6. Different approaches and tools
• Virtualization
• Configuration Management
• Containers

7. Containerization = standardization

8. Containerization = Separation of Concerns

9. Configuration Management
Remember the exact steps needed for
setup and do it all over again for all of
your servers (a recipe)
Docker/Containers
Set up a container/image just once with all
the necessary configuration, then deploy the
same image to all of your servers (a golden
image)
What’s the difference?

10. Terminology: Images and Containers
Image: A master template for creating Docker
containers, analogous to virtual machine
instances (a “golden image”)
Container: An instance of an image; multiple
containers can be created from a single image.
A container contains isolated processes and
filesystems acting in a similar fashion as virtual
machines; however, a container only includes
the filesystem on top of a shared kernel.

11. Virtual Machines Containers
What’s the difference? Virtual Machines vs Containers

12. Virtual Machines
• Kernel not shared between virtual
machines
• Isolated operating systems
• Long-lasting use
• Slower to get running
• Many startup processes
• A single virtual machine image can be
used for multiple virtual machine
clones
Containers
• Kernel of linux host shared between all
containers
• Isolated processes/filesystems
• Ephemeral/long-lasting usage
• Fast to get running
• One startup process
• A single Docker image can be used for
multiple container instances
What’s the difference? Virtual Machines vs Containers

13. What is Docker used for?
• Ephemeral (temporary) isolated processes (e.g. Codepen, Codeship)
• Short running tasks, maintenance scripts, or worker processes that
receive then process a workload
• Running and deploying stateless applications
• Web frontends and backend APIs
• Running isolated environments with imposed CPU/memory limits
• …and more!

14. This means that containers are
• More lightweight
• Can be started, stopped, and
restarted more quickly
• Easier to migrate
• Easier to communicate
between containers
What’s the difference? Virtual Machines vs Containers

15. Docker Server vs Docker Client
Docker server/daemon:
The docker server/daemon runs containers within as
processes, acting as a virtual bridge to the host operating
system (containers are isolated)
Docker client: The command line interface (CLI) that is
able to connect to the Docker server (specified by the
DOCKER_HOST environmental variable) and tell it what to
do. This can run on your local machine or on the same
host as the Docker server.

16. Docker Server vs CLI

17. Docker Server vs CLI

18. Docker Server vs CLI

19. Docker Server vs CLI

20. Docker Server vs CLI

21. WORKSHOP
Install Docker

22. Installation - Linux
curl -fsSL https://get.docker.com/ | sh
service docker start
Will run a setup script for installing docker
Easy setup

23. Installation - Linux
apt-get update
apt-get purge lxc-docker*
apt-get purge docker.io*
apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys
58118E89F3A912897C070ADBF76221572C52609D
echo "deb https://apt.dockerproject.org/repo debian-jessie main" >
/etc/apt/sources.list.d/docker.list
apt-get -y install apt-transport-https
apt-get -y update
apt-get -y install docker-engine
service docker start
Debian/Ubuntu
curl https://raw.githubusercontent.com/anonmily/scripts/master/docker-setup-debian | bash
Or, just

24. Installation - Linux
yum install docker
service docker start
Fedora
curl https://raw.githubusercontent.com/anonmily/scripts/master/docker-setup-yum | bash
Or, just

25. Installation – Non-Linux
• Download and install the Docker
Toolbox
https://www.docker.com/docker-
toolbox
• Open the Docker Quickstart
Terminal

26. WORKSHOP
Docker Server/CLI

27. Docker Server/CLI
docker-machine create –driver virtualbox host1
docker-machine create –driver virtualbox host2
docker-machine create –driver virtualbox host3
Create a new docker host
docker-machine ls
List docker hosts

28. Docker Server/CLI
docker-machine stop host1
Stop docker host
docker-machine start host1
Start docker host
docker-machine restart host1
Restart docker host

29. Docker Server/CLI
docker-machine ip host1
Get IP address of host
docker-machine env host1
Get environmental variables of the host

30. Docker Server/CLI
eval $(docker-machine-env host1)
Set environmental variables of CLI to communicate with a host
** If you get a “Cannot connect to the Docker daemon. Is the docker daemon running on this host?” error
when attempting to use the Docker CLI, make sure the environmental variables are set for your Docker host

31. Docker Images
• Docker images are a saved state of the
container. They’re the “golden image” for
your containers, and multiple containers
based off the same mage can be run at
the same time (executing different
commands etc in the same environment if
necessary)
• Image ID = hashed representation of the
image, a unique identifier
• A Dockerfile is a file that describes all the
steps needed to build a Docker image

32. Docker Images
• Images can be tagged with a name
and a version label (e.g.
nginx:latest, ubuntu:14:04)
• Images are stored in and can be
retrieve from Docker Repositories
• Docker Hub: Public repository with
common base images
• Private Registry: Deploy your own
Docker registry

33. Storing Docker Images
• Docker registry: A server that hosts your
Docker images; it acts in a fashion
analogous to repositories in that you can
push and pull images from the registry.
You can use a public registry like Docker
hub, or you can setup your own for private
images.
• Docker Hub: A public Docker registry that
is the default for pulling images. It
provides many common base images such
as Debian, Ubuntu, Fedora, etc.

34. Docker Hub

35. Deploy your own registry server

36. WORKSHOP
Docker Images

37. Docker Images
docker pull nginx:latest
Pull/get an image (from Docker Hub)
# login to DockerHub
docker login
# private registry
docker login https://myownregistry.com:5000
Login to a registry
• Docker will save your login credentials in ~/.docker/config.json
docker images
See your downloaded/available images

38. Docker Images
docker build –t webapp1:latest .
Build a new image tagged “webapp1:latest” from a Dockerfile
docker run --name="myapp" -p 80:80 -d nginx:latest nginx
-g "daemon off;"
Run a container from an image
• --name=“myapp” Run a new container called “myapp”
• -p 80:80 Expose port 80 of the host and map it to port 80 of the container
• -d Run daemonized
• nginx:latest Base image
• nginx –g “daemon off;” Command to start the container with

39. Docker Images
docker exec –it nodeapp bash
Execute a command into a container
docker ps # running containers
docker ps –a # all containers
List containers
docker stop nodeapp
Stop container
docker rm nodeapp
Remove container

40. Docker Images
docker save myimage:latest > myimage.tar
Save an image to a tarball
docker import myimage.tar
Import an image from a tarball
docker commit –m “newconfig” mycontainer myimage:latest
Commit/save the current state of a container to the image

41. Docker Images
docker rmi myimage:latest
Remove an image
docker rmi $(docker images –q –f “dangling=true”)
Delete all untagged images
docker rmi $(docker images –q -)
Delete all images on Docker host

42. What is a Dockerfile?
• Instructions for how to build a
Docker image
FROM anonmily/node:latest
MAINTAINER Michelle Liu
<michelle@michelleliu.io>
COPY src/node_modules /src/node_modules
COPY certs /src/certs
EXPOSE 443
WORKDIR /src
ENV PATH /src/bin:$PATH
COPY src/bin /src/bin
COPY src/app /src/app
COPY src/server.js src/app.js
src/package.json Makefile /src/
CMD ["startserver"]

43. Anatomy of a Dockerfile
• FROM what base image to use for the new image
• MAINTAINER who maintains the image
• COPY source destination copy files from the source location to destination
• ENV set environmental variables
• WORKDIR set working directory of the container
• CMD run command
• EXPOSE indicates what ports should be available for exposure

44. Dockerizing a Node application
FROM anonmily/node:latest
MAINTAINER Michelle Liu
<michelle@michelleliu.io>
COPY src/node_modules /src/node_modules
COPY certs /src/certs
EXPOSE 443
WORKDIR /src
ENV PATH /src/bin:$PATH
COPY src/bin /src/bin
COPY src/app /src/app
COPY src/server.js src/app.js
src/package.json Makefile /src/
CMD ["startserver"]
/Src
app/
app.js
bin/
startserver
certs
gulpfile.js
node_modules
server.js
Makefile
Bin/
Certs/
Src/
app.js
bin/
startserver
gulpfile.js
node_modules
server.js
Server.js
Production.env
Dockerfile
Makefile
Original Folder Docker Container

45. Utilizing the Layer Cache
FROM anonmily/node:latest
MAINTAINER Michelle Liu <michelle@michelleliu.io>
COPY src/node_modules /src/node_modules
COPY certs /src/certs
EXPOSE 443
WORKDIR /src
ENV PATH /src/bin:$PATH
COPY src/bin /src/bin
COPY src/app /src/app
COPY src/server.js src/app.js src/package.json
Makefile /src/
CMD ["startserver"]
Least changed
files on top
More
frequently
changed files
on bottom

46. Building the image
# ./bin/buildapi
docker build -t myregistry.com/nodeapi:latest .
# ./bin/pushapi
docker push myregistry.com/nodeapi:latest

47. Updating to a newer image
# ./bin/updatecontainer
docker pull myregistry.com/nodeapi:latest
docker kill nodeapicontainer;
docker rm nodeapicontainer;
docker run --name nodeapi01
-p 443:443
-dit
--env-file /home/production.env
myregistry.com/nodeapi:latest
startserver

48. An easy way to deploy
1. Push the new image up onto the Docker registry (e.g. 1.0.0)
2. From the servers, pull down the new image
3. Kill the currently running container based off the old outdated image
4. Run a new container based off the new image

49. Updating to a newer image
#!/bin/bash
docker build -t myregistry.com/nodeapi:latest .
docker push myregistry.com/nodeapi:latest
ssh -i ~/.ssh/mysshkey root@api.mysite.com 'bash' <
bin/updatecontainer
ssh -i ~/.ssh/mysshkey root@api.mysite2.com 'bash' <
bin/updatecontainer
ssh -i ~/.ssh/mysshkey root@api.mysite3.com 'bash' <
bin/updatecontainer

50. Startserver
#!/bin/bash
pm2 dump
pm2 start /src/server.js -i 0 --name
nodeapi --no-daemon &
If you want to start your container up with more than
one command, use a bash script

51. Docker remote API
An API for the Docker daemon/server that allows you to make requests
to/query the server for creating/editing or for information on
containers/images.

52. Docker remote API
By default, the Docker daemon will run on the unix port at
/var/run/docker.sock. To get started with the Docker remote API, make sure
that you have a cURL version greater than 7.40 so that the –unix-socket
option is available. Then, we can use curl to interact with the remote API by:
curl --unix-socket /var/run/docker.sock http://containers/json

53. Docker remote API
It’s also possible to bind the Docker daemon to a TCP port at startup by:
docker daemon –H tcp://0.0.0.0:2375 –H /var/run/docker.sock
It will then be possible to access the remote API on the host publicly (though
it is a security issue).
curl http://localhost:2375/containers/json

54. More resources
• http://view.dckr.info/DockerIntro.pdf
• http://view.dckr.info/DockerAdvanced.pdf
• https://docs.docker.com/engine/articles/dockerfile_best-practices/
• http://blog.thoward37.me/articles/where-are-docker-images-stored/
• http://blog.trifork.com/2013/12/24/docker-from-a-distance-the-remote-api/