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Papers We Love: Jails and Zones


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Slides for my @papers_we_love talk at @paperswelovenyc on February 11, 2016. Video to come!

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Papers We Love: Jails and Zones

  1. 1. Papers We Love: Jails and Zones CTO Bryan Cantrill @bcantrill
  2. 2. Papers we love: Jails and Zones • Discussing two important papers that form the foundation of thinking about OS-based virtualization and containers: • Jails: Confining the Omnipotent Root by Poul-Henning Kamp and Robert Watson, presented at SANE 2000 • Solaris Zones: Operating System Support for Consolidating Commercial Workloads by Dan Price and Andy Tucker, presented at LISA 2004 • As much as possible, want to let these papers speak for themselves — and provoke discussion!
  3. 3. Jails: Problem statement
  4. 4. Jails: Prior work
  5. 5. Jails aside: chroot(2)
  6. 6. Jails: Proposed solution
  7. 7. Jails: Advantages
  8. 8. Jails: jail(2)
  9. 9. Jails: Confining the filesystem
  10. 10. Jails: Confining the network
  11. 11. Jails: Implementation
  12. 12. Jails: Network management complexities
  13. 13. Jails: Filesystem management complexities
  14. 14. Jails: User management complexities
  15. 15. Jails: Unintended consequences
  16. 16. Jails: Networking limitations
  17. 17. Jails: Resource management limitations
  18. 18. Jails: Management limitations
  19. 19. Jails: Epilogue • Jails became easier to manage with jls/jps/ezjail/iocage • Jails were allowed to have multiple IPv4 addresses • Some jail-based resource management was added, including CPU binding and • System V IPC was virtualized, but remains out-of-tree • VIMAGE added exclusive IP stacks to jails, but it remains a build- time option and “is considered experimental”
  20. 20. Zones: Problem statement
  21. 21. Zones: Problem statement detail
  22. 22. Zones: Proposed solution
  23. 23. Zones: Block diagram
  24. 24. Zones: Design principles
  25. 25. Zones: Design principles, cont.
  26. 26. Zones: State model
  27. 27. Zones: Configuration
  28. 28. Zones: Installation
  29. 29. Zones: Application environment
  30. 30. Zones: Virtual platform
  31. 31. Zones: Console
  32. 32. Zones: Process model
  33. 33. Zones: Process model, cont.
  34. 34. Zones: IPC
  35. 35. Zones: System V IPC
  36. 36. Zones: Networking
  37. 37. Zones: Filesystem
  38. 38. Zones: Resource management
  39. 39. Zones: Observability and debugging
  40. 40. Zones: Security experience
  41. 41. Zones: Workloads
  42. 42. Zones: Epilogue • Crossbow added virtual NICs and exclusive IP stacks — and anti- spoof allowed exclusive IP stacks to be deployed safely • Resource management became much more complete, adding memory capping, CPU capping, I/O throttling • ZFS revolutionized zone installation/configuration • With introduction of IPS packaging, Solaris got rid of so-called “sparse root” zones... • ...and Joyent added sparse root zones back to SmartOS (thanks to no IPS and no global zone package management)
  43. 43. Zones: Epilogue, cont. • Sun added notion of branded zones in 2006, including a nascent Linux brand (LX) — and then ripped LX out in 2010 • LX brand revived by Joyent in 2014 in SmartOS and completed (first deployed into production in early 2015) • Overlay network support added to SmartOS by Joyent, allowing software-defined VXLAN-based networks in non-global zones
  44. 44. Jails and Zones: Conclusions • Each of these technologies has served to inspire the other: zones was explicitly inspired by jails — and the jails networking work has been explicitly inspired by Crossbow • These two papers are important because they capture not just the what, but the why of their respective works • These technologies were both ahead of their time; it’s invaluable now to be able to understand their motivations! • In the words of the late, great Jim Gray: You need to write more!