Retrouvez la présentation de Claudia Beresford & Tiago Scolar de Pivotal lors de la conférence du Paris Container Day

1. Production FS:
Adapt or Die

2. hello!
Claudia & Tiago
callisto13 tscolari

3. Summary
✘ Glossary - What is a Root Filesystem?
✘ What is CloudFoundry?
✘ Warden
✘ Garden Linux
✘ Garden runC
✘ GrootFS + Garden runC
✘ The Future
✘ Questions?

4. 1) Directory hierarchy and structure
1) Type: How the data is organised
What is a FileSystem?

5. ✘ Top of the dir structure
✘ Mount point for other FSes at boot
✘ Contains all critical startup files
✘ Sets state of system
✘ Has tools for recovery of broken system and data
What is a Root FileSystem?

6. What is a RootFS?
Host

7. What is a RootFS?
Container
Host

8. ✘ Open Source Platform as a Service
✘ Development started in 2009 (VMWare)
✘ First released in 2011
✘ Run application inside containers
✘ Supports buildpacks and Docker images
What is CloudFoundry?

9. Provide framework and runtime support for applications
Officially supported:
○ Binary
○ Go
○ Java
○ .Net Core
○ Node.js
Buildpacks?
○ PHP
○ Python
○ Ruby
○ Static File

10. Buildpack
Buildpack
RootFS
Application Code
RootFS
Droplet
Compilation

11. Droplet

13. ✘ Multitenancy
✘ Application
Quotas
Isolation
✘ Independent of Host FS
What did CF need?

14. 2011
✘ Kernel 2.6
✘ Containers?
✘ No user namespace available

15. 1.
AUFS + WARDEN
2011

16. Warden
✘ Developed in Ruby and C
✘ Initially with LXC
✘ Coupled to Linux
Namespaces (exc User) &
cgroups

17. WHY AUFS?
✘ Mounting the rootfs
was faster than
copying it
✘ No duplicated files
But...
✘ No support for quotas
✘ Not in Mainline Kernel

18. RootFS Mnt: RootFS
RW Layer
Droplet
Mnt: RootFS
RW Layer
Droplet
Mnt: RootFS
RW Layer
Droplet
...
root root root root
unique uid
APP1 APP2 APP3

19. 2013-2014
✘ User namespaces
✘ Security
✘ Scalability
✘ Containers

20. 2.
BTRFS + GARDEN LINUX
2014/2015

21. Garden & Diego
✘ Replacement for Warden
✘ Go (w)arden - Garden
✘ Platform Agnostic API -
future support for windows
✘ New scheduler
✘ DEA(Go) - Diego

22. + Docker Images
✘ No control over
RootFS anymore
✘ Security Risks ✘ User namespaces

23. Why BTRFS?
✘ Dependence on Docker graph
driver
✘ Built in support for quotas
✘ The other options were:
Overlay - not mature
DeviceMapper - required LVM
ZFS - proprietary

25. Everything was changing
✘ New scheduler
✘ New container runtime
✘ New container Filesystem
✘ New IAAS

26. And...
✘ Huge Performance Hit: BTRFS blamed (eventually)
✘ Theory was BTRFS garbage collection was consuming all IOPS from the cells
✘ BTRFS new and didn’t have enough support at the time

27. 3.
AUFS + GARDEN LINUX
October 2015

28. Why AUFS, again?
✘ Familiarity
✘ But…
Quotas?

29. RootFS Mnt: RootFS
mnt:/dev/loop1
Droplet
...
root root
APP1
Mnt: RootFS
mnt:/dev/loop2
Droplet
root
APP2
Mnt: RootFS
mnt:/dev/loop3
Droplet
root
APP3
sparse

30. 2015
✘ runC

31. 4.
AUFS + GARDEN RunC
May 2016

32. Open Containers Initiative / RunC
✘ Open Standard for containers specification
✘ Implementation of OCI container specs

33. Garden RUNC
✘ Rewritten to use RunC
✘ More GO, Less C
✘ More Security

34. AUFS...
✘ More bugs
✘ Distraction

35. 2015/2016
✘ OCI: Image-Spec
✘ GrootFS - new project to replace Garden Linux backend
Dedicated team
✘ Security: Garden runC Rootless

36. 5.
BTRFS + GROOTFS +
GARDEN runC
June 2016

37. Why BTRFS, again?
✘ Snapshotting: plays well with
container images
✘ Could be (almost) rootless
✘ Quotas
✘ Previous issues fixed in kernel
4.4
✘ Big companies investing
✘ Support from Canonical

38. Container Image

39. Snapshot: rootfs
Droplet
1001
Buildpack App
Snapshot: layer1
1001
Docker Img App
Snapshot: layer2
Snapshot: layer3

40. But...
✘ New performance issue: `btrfs enable quota`

41. OVERLAY/XFS +
GROOTFS + GARDEN
runC
6.
February 2017

42. Why Overlay+XFS?
✘ Maturity ✘ Overlay for layering ✘ XFS for quotas

43. XFS folder app1/
Overlay mount
upperdir: app1/diff
lowerdirs: layer1:layer2:layer3
App 1
XFS folder app2/
Overlay mount
upperdir: app2/diff
lowerdirs: layer1:layer2:layer3
App 2

45. The Future

46. What’s Next?
✘ EXT4
Kernel 4.5 in Stemcell
Match host FS
✘ ShiftFS
On the fly user mappings
No translation layer

47. Conclusion
✘ Nothing is forever
✘ There are always risks
Agility is key
✘ Focus!

48. thanks!
Any questions?
callisto13 / cberesford@pivotal.io
tscolari / tscolari@pivotal.io
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