A Gentle Introduction to Docker
Carolyn Van Slyck
The Hype
🐳 🐳 🐳 🍄
Demystifying Docker
Classic Application Deployment
Virtual Application Deployment
Containerized Application Deployment
Linux Containers (LXC)
namespaces + cgroups = ISOLATION
Linux Namespaces
Isolation without virtualization
- Process (pid): Can't see other processes
- Filesystem (mnt): Can only see its own files
- Networking (net): Gets its own network interface
Control Groups (cgroups)
Restrict resource usage: CPU, RAM, IO, Network
The Matrix is everywhere. It is all around us. Even now, in this very room. You can see it when you look out your window or when you turn on your television. You can feel it when you go to work... when you go to church... when you pay your taxes. It is the world that has been pulled over your eyes to blind you from the truth...
That you are a slave, Neo. Like everyone else you were born into bondage. Into a prison that you cannot taste or see or touch. A prison for your mind.
Morpheus in The Matrix
So what is Docker, anyway?
linux container + packaging + tools
Docker took something that previously was only an option for highly motivated sysadmins, and gave it away to the masses. Carolyn Van Slyck
Docker Image Packaging
Docker Tools
docker run --detach --volume `pwd`:/var/www --publish 80:80 nginx
What does this let us do?
Moves knowledge on how to run your app out of a readme and into code
| VMs | Docker | Chef | |
|---|---|---|---|
| Isolated | ✅ | ✅ | ❌ |
| Repeatable | ✅ | ✅ | ✅ |
| Sharable | ✅ | ✅ | ✅ |
| Maintainable | ❌ | ❌ | ✅ |
The Catch
- Filesystem is ephemeral, not persistent ➡ External file system
- Images aren't enough ➡ Compose, Helm
- Application Lifecycle Management ➡ Swarm, Kubernetes
How to get started
Define a Docker image
Dockerfile
FROM ubuntu:16.04
COPY bin/Linux/x86_64/magic /
CMD ["/magic"]
Build a Docker image
docker build -t carolynvs/magic .
Publish a Docker image
docker push carolynvs/magic
Run a Docker container
docker run --rm carolynvs/magic
Beginner Resources
Advanced Resources
Thank you
