This document provides an introduction to Docker, including what Docker is, how it differs from virtual machines, basic Docker commands, examples of running common applications like GitLab and JIRA in Docker containers, and considerations for when to use and not use Docker. Docker allows containerized execution of isolated applications, sharing resources for lighter weight usage than virtual machines. Examples demonstrate pulling public images and running containers from them to execute applications like Python, GitLab and JIRA.

1. Intro to Docker
CPA JUG
2017-09-14
Matt tomasov - matthewjt@gmail.com
Mike Melusky - mike.melusky@gmail.com

2. What is Docker?
Docker is containerized management and
execution of isolated applications.
Virtual Machines (VM Ware, VirtualBox, etc)
Parallells
WINE ( www.winehq.org )

3. How is Docker different
from a Virtual Machine
Virtual Machines
- Each VM needs its own resources from the Host OS and
each VM image needs its own local resources.
- Very little is shared.
Docker
- Lightweight Docker engine runs on the Host OS (Can run
natively or in lightweight virtual machine)
- Docker engine shares image resources.
- No need to boot an entire OS for one application.

4. Basic Docker Commands

5. List running containers
$ docker ps

6. Create a Container
$ docker run

7. List images
$ docker images

8. Create container from image
$ docker run hello-world

9. Run python on the hello-world container
$ docker run hello-world
python --version

10. Pull image containing python
$ docker pull python

11. Run container from that image:
$ docker run python
python --version

12. View the image's directory:
$ docker run python ls

13. What can we run in Docker?
● Gitlab
● Atlassian JIRA
● Atlassian Confluence
● JetBrains YouTrack

15. Docker Hub Image
$ docker pull gitlab/gitlab-ce

16. Run GitLab Image
sudo docker run --detach
--hostname gitlab.example.com
--publish 443:443 --publish 80:80 --publish 22:22
--name gitlab
--restart always
--volume /srv/gitlab/config:/etc/gitlab
--volume /srv/gitlab/logs:/var/log/gitlab
--volume /srv/gitlab/data:/var/opt/gitlab
gitlab/gitlab-ce:latest

18. Run a JIRA image in Docker
$ docker run --detach --publish
8080:8080 cptactionhank/atlassian-
jira:latest

20. Official Image on Docker Hub
$ docker pull atlassian/confluence-server

21. Run Confluence Image
$> docker run -v /data/your-confluence-
home:/var/atlassian/application-data/confluence --
name="confluence" -d -p 8090:8090 -p 8091:8091
atlassian/confluence-server

23. Third-party image on Docker Hub
$ docker pull zoer/youtrack

24. Demo - Create your own Docker image (Matt)
- Demo Spring Boot application
- Web application with index.jsp
- Tomcat integrated in application
- Can be run using java -jar <application jar>
- Dockerfile
- Docker build
- Docker docker run

25. When to “Dockerize”
Simple applications
Configuration can be “externalized”
Multiple applications, multiple dependencies, “install hell”
Constant updates
Distribute easily
Install can be scripted

26. When NOT to “Dockerize”
Application configuration is not easily upgraded
No need for backups
Install is complicated and requires a lot of human thought/interaction

27. References
Docker - https://docker.io
https://www.docker.com/what-docker
https://www.docker.com/what-container
ZDNet article explaining why Docker is great - http://www.zdnet.com/article/what-is-docker-
and-why-is-it-so-darn-popular/