1. Docker Internals
SF Docker Meetup at Twilio
11/14/2013
Docker version 0.6.6 / 0.7.0-rc5
##dockermeetup
By Guillaume J. Charmes <guillaume@docker.com>
@charme_g

2. This is your last chance
1.
2.
3.
4.
Isolation
Images
Process Management
Roadmap

3. Isolation
• LXC
•
•
•
•
Cgroups/Namespaces
Processes
Mounts
Network
• Network
• NAT (DOCKER chain)
• Expose / Links
• File System
• Chroot on steroids

4. Isolation
• Isolation: Namespaces
• Only 1 syscall (setns()). No hypervisor
• Mounts, Uts (hostname), Net, Pid, IPC, User
• Resource management: Cgroups
• Memory Limitation
• CPU Shares
• Future: blkio

5. Isolation
• Network
•
•
•
•
Bridge
Veth
NAT
Expose / Links
• File System
• Chroot++
• Image management

6. 1.
2.
3.
4.
Isolation
Images
Process Management
Roadmap

7. Images
• AUFS
• Image format
•
•
•
•
Base image
Layer + parent id
Whiteouts (.wh.)
Difference Image vs Container
• Registry
• Future
• Devicemapper
• Backend interface

8. Images
• Why AUFS?
• Production usage for years
• Layers
• Multiple RO layers, 1 RW -> Diff
• Limitations
• 42 layers
• Whiteouts
• Deletion management

9. Images
• Image format
• Payload (layer)
• Metadata (parent id)
• Image vs Container
• Differences
• Future: Unified format

10. Images
• Image sharing: Registry
• Push/Pull via diffs
• Future
• Backend interface / Devicemapper
• Unified image format: whiteouts (.wh.)

11. 1.
2.
3.
4.
Isolation
Images
Process Management
Roadmap

12. Process Management
• Docker daemon
• Transports unix/tcp
docker run internals
• Attach logic
• Logs
• Host Integration
• Dockerfile
• RUN
• EXPOSE
• What is the Context?
• Service Discovery

13. Process Management
• Docker daemon
• Transports: docker –d –H tcp://127.0.0.1:4243 –H unix:///var/run/docker.sock
• Holds all containers
• Handles the logging
• Docker client
• Everything uses the Remote API

14. Process Management
docker run
• Create
• Start
• Attach
internals
• General Config vs Host Config
• Attach protocol
• TTY
• Non-TTY

15. 1.
2.
3.
4.
Isolation
Images
Process Management
Roadmap

16. Roadmap
• Docker 0.7
• File system backend interface
• Docker 0.8
• Isolation backend interface
• Full introspection
• Future
• Ambassador Pattern

17. Conclusion
• Wide global support with backend interfaces
• Service discovery improvement
• Road to multi host / orchestration

18. Thank you!
www.docker.io