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CentOS Virt SIG - Community virtualization packages on an immutable core

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CentOS is a "distribution" with a rather unique description: it is a free (gratis) clone of a commercially-supported "distribution" with all the branding removed. Being enterprise-grade distribution means solid and well-tested; but it also means not having the latest functionality. It also means having a small enough feature set to provide commercial support in a viable manner: and that typically means choosing one technology and sticking with it. But what if you wanted your entire system to be solid, and well-tested, but want the latest features for one particular package or program? Or what if you really wanted an enterprise system, but wanted to use one of the alternate technoligies that were not selected? This is where CentOS SIGs come in. The new CentOS is still at its core a clone of an upstream enterprise distribution. But having had success with the Xen4CentOS project, which provided a version of Xen to run on CentOS 6, they have now generalized the process. This talk will talk about CentOS SIGs: the vision, the structure, what SIGs are available. We will compare and contrast them to other community distro development models like Fedora, OpenSuSE, Debian, Ubuntu, and so forth. We will also share lessons from the CentOS Virt SIG, in which a number of virtualisation and related technologies such as Xen, oVirt, Docker and others collaborate.

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1

Lars Kurth (standing in for George Dunlap) Lead CentOS Virtualization SIG Community Manger, Xen Project Chairman, Xen Project Advisory Board lars_kurth

2

Community-oriented distros Debian, Gentoo, BSDs Enterprise targeted distros RedHat, SuSE Company-sponsored community distros Fedora, OpenSuSE Company-patched community distro Ubuntu Community-rebuilt distros CentOS, Scientific Linux Mcamcamca @ Flickr

3

Stability Use old versions Backport significant new functionality / bug fixes Supportability Don’t try to support everything Pick one technology and support that one well Eliminate all non-supported technologies

4

Community-rebuilt distro ...with a twist SIG = Special Interest Group

5

Released 10 July 2011 6 months after the release 10000’s of users still using CentOS 5 The reason? Xen Project RHEL had purchased Qumranet Made KVM the hypervisor of choice for RHEL6 Tons of users who still wanted to use Xen CentOS community members approached the Xen Community At FOSDEM 2012, we started to make a plan to fix this

6

Supplementary yum repo Xen Domain 0 kernel libvirt

7

What if people want all the boring, slow-changing stability of an enterprise kernel, except... ...for one application, where they want something newer? ...a different technology than the one chosen by the “commercial upstream”?

8

Community-developed “patches” on the immutable core Mechanism: Additional yum repo that adds / overrides core packages General approach: Make it up as we go along Mcamcamca @ Flickr

9

SIGs Approved: Cloud SIG (OpenStack, &co ) Cloud Instance SIG (Amazon instances, &c) Virtualization (Xen, Docker, oVirt) Storage (CentOS as a storage node) Atomic ... it would seem so!

10

Maria Ly @ Flickr Issues we have worked through in the last 12 months Some are not yet fully resolved

11

Moving from a small tight-knit group to larger disaggregated groups Everyone’s trusted to Want to trust everyone, but trust needs to be limited Not unique to CentOS model Complicated by the already-large community Also See: cbs.centos.org/koji/ wiki.centos.org/HowTos/CommunityBuildSystem CERN CentOS Dojo presentation @ bit.do/centos-sig-cbs

12

Not even minor fixes can be added to the CentOS-Core So even minor changes mean re-building the whole package Example: virt-install uses blktap1 instead of blktap2 Re-building also means tracking Core changes Nicholas A. Tonelli @ Flickr

13

Example: Docker for C7 (in the Virt SIG) uses stock C7 kernel Xen for C7 will need a domain-0 enabled kernel Solutions: Break down into virt7-xen and virt7-docker repos Share the same SIG delivered kernel Challenge: Avoiding repo multiplication Mcamcamca @ Flickr

14

What if you want to install two different SIGs, but: The two SIGs require different versions of the same package (e.g., the kernel) General approach: We’ll figure it out when we get there. Mcamcamca @ Flickr

15

CentOS core has the stability guarantees of the upstream enterprise OS CentOS SIGs don’t have nearly as much testing behind them But they still carry the CentOS name Oversight by CentOS board member important

16

Maintainers having taken ownership for several technologies: Xen, Docker, oVirt wiki.centos.org/SpecialInterestGroup/Virtualization

17

Done: Projects building in the community build system for CentOS 6 Updated to Xen 4.4.1 and libvirt 1.2.10 Already a user: “yum update” wiki.centos.org/HowTos/Xen/Xen4QuickStart To-do: Build for CentOS 7 Update kernel to 3.14 (currently 3.10)

18

Docker 1.4.1 for CentOS 7 in CBS Close to release (in testing, tag “virt7-testing”) Working on Rocket

19

Added to Virt SIG 6 weeks ago Goals: Build qemu-kvm binary with live snapshot support oVirt Live “spin” oVirt Node “spin” Interface with Storage SIG … for GlusterFS support

20

See if there’s an existing SIG you can join E-mail centos-devel with your proposal Convince one of the CentOS Board members to sponsor you. wiki.centos.org/SpecialInterestGroup www.centos.org/about/governance/sigs

21

Slides on www.slideshare.net/xen_com_mgr/

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CentOS Virt SIG - Community virtualization packages on an immutable core

  • 1. Lars Kurth (standing in for George Dunlap) Lead CentOS Virtualization SIG Community Manger, Xen Project Chairman, Xen Project Advisory Board lars_kurth
  • 2. Community-oriented distros Debian, Gentoo, BSDs Enterprise targeted distros RedHat, SuSE Company-sponsored community distros Fedora, OpenSuSE Company-patched community distro Ubuntu Community-rebuilt distros CentOS, Scientific Linux Mcamcamca @ Flickr
  • 3. Stability Use old versions Backport significant new functionality / bug fixes Supportability Don’t try to support everything Pick one technology and support that one well Eliminate all non-supported technologies
  • 4. Community-rebuilt distro ...with a twist SIG = Special Interest Group
  • 5. Released 10 July 2011 6 months after the release 10000’s of users still using CentOS 5 The reason? Xen Project RHEL had purchased Qumranet Made KVM the hypervisor of choice for RHEL6 Tons of users who still wanted to use Xen CentOS community members approached the Xen Community At FOSDEM 2012, we started to make a plan to fix this
  • 7. What if people want all the boring, slow-changing stability of an enterprise kernel, except... ...for one application, where they want something newer? ...a different technology than the one chosen by the “commercial upstream”?
  • 8. Community-developed “patches” on the immutable core Mechanism: Additional yum repo that adds / overrides core packages General approach: Make it up as we go along Mcamcamca @ Flickr
  • 9. SIGs Approved: Cloud SIG (OpenStack, &co ) Cloud Instance SIG (Amazon instances, &c) Virtualization (Xen, Docker, oVirt) Storage (CentOS as a storage node) Atomic ... it would seem so!
  • 10. Maria Ly @ Flickr Issues we have worked through in the last 12 months Some are not yet fully resolved
  • 11. Moving from a small tight-knit group to larger disaggregated groups Everyone’s trusted to Want to trust everyone, but trust needs to be limited Not unique to CentOS model Complicated by the already-large community Also See: cbs.centos.org/koji/ wiki.centos.org/HowTos/CommunityBuildSystem CERN CentOS Dojo presentation @ bit.do/centos-sig-cbs
  • 12. Not even minor fixes can be added to the CentOS-Core So even minor changes mean re-building the whole package Example: virt-install uses blktap1 instead of blktap2 Re-building also means tracking Core changes Nicholas A. Tonelli @ Flickr
  • 13. Example: Docker for C7 (in the Virt SIG) uses stock C7 kernel Xen for C7 will need a domain-0 enabled kernel Solutions: Break down into virt7-xen and virt7-docker repos Share the same SIG delivered kernel Challenge: Avoiding repo multiplication Mcamcamca @ Flickr
  • 14. What if you want to install two different SIGs, but: The two SIGs require different versions of the same package (e.g., the kernel) General approach: We’ll figure it out when we get there. Mcamcamca @ Flickr
  • 15. CentOS core has the stability guarantees of the upstream enterprise OS CentOS SIGs don’t have nearly as much testing behind them But they still carry the CentOS name Oversight by CentOS board member important
  • 16. Maintainers having taken ownership for several technologies: Xen, Docker, oVirt wiki.centos.org/SpecialInterestGroup/Virtualization
  • 17. Done: Projects building in the community build system for CentOS 6 Updated to Xen 4.4.1 and libvirt 1.2.10 Already a user: “yum update” wiki.centos.org/HowTos/Xen/Xen4QuickStart To-do: Build for CentOS 7 Update kernel to 3.14 (currently 3.10)
  • 18. Docker 1.4.1 for CentOS 7 in CBS Close to release (in testing, tag “virt7-testing”) Working on Rocket
  • 19. Added to Virt SIG 6 weeks ago Goals: Build qemu-kvm binary with live snapshot support oVirt Live “spin” oVirt Node “spin” Interface with Storage SIG … for GlusterFS support
  • 20. See if there’s an existing SIG you can join E-mail centos-devel with your proposal Convince one of the CentOS Board members to sponsor you. wiki.centos.org/SpecialInterestGroup www.centos.org/about/governance/sigs

Editor's Notes

  1. Note: all of these work on the basis that each package is unique and that versions of packaged software is tightly managed
  2. Mention: Somewhat different to what SIGs are trying to achieve
  3. Bridge: history of how SIGs came about
  4. A lot more than in the previous release. Took until CentOS 6.3 until more than 50% of users had migrated
  5. This slide sort of assumes that people know the primary attraction of CentOS: the “slow, stable, enterprise-yness” of it. I was looking for a good place to introduce this earlier.
  6. Clarify: into RHEL The blktap2 fix for virt-install is a one-line fix.
  7. The first mean that packages from the two repos cant be used together
  8. CentOS Atomic-host from Atomic uses docker from virt-sig Planned: oVirt is planning to use GlusterFS from Storage SIG … There are a few more --- Need some process at some stage
  9. TODO: Main link … TODO: Just a yum update? Ask KB
  10. Getting started docs + announcement Mention that we agreed to try and use a common kernel for the Virt SIG builds Discussing: Trunk Docker packages
  11. In the Virt SIG we require an individual (or several) to step up and maintain the relevant packages and participate in the SIG