Latest revision as of 02:42, 5 May 2014

Modular Kernel Packaging for Cloud

Summary

Kernel modules that are not necessary in virtualized environments become optionally (un)installable.

Owner

Name: Cloud SIG / Sandro Mathys, Kernel Team / Josh Boyer
Email: red@fedoraproject.org, jwboyer@fedoraproject.org
Product: All Cloud products
Responsible WG: Cloud

Current status

Targeted release: Fedora 21
Last updated: 2014-03-13
Tracker bug: #1081581

Detailed Description

Space is precious in the cloud, therefore the Cloud SIG tries to keep the images' footprint as small as reasonably possible. Therefore, we'd like to split the kernel into two (plus one meta) packages. One package would contain the core modules, i.e. a minimum(-ish) set of modules to only just be able to run in virtualized environments. And another package for the rest. The 'kernel' package would then become a meta package that installs both (-core and -modules).

Benefit to Fedora

Possibility to install Fedora with a smaller footprint.
Official Fedora cloud images will become smaller.
Possibility to avoid respinning images for security updates if issue is in a driver not included in kernel core

Scope

Normal installations will continue installing the kernel (meta-)package and users should not notice any difference. Same goes for updating from earlier Fedora releases. But where desired, it should become possible to install only a reasonably minimal subset of kernel modules. Both kernel and kernel-core will Provide "kernel", therefore the "install instead of update" magic of yum/dnf will work as expected even if only kernel-core is installed.

Proposal owners: The kernel package needs to be changed to produce a meta- (kernel) and two new packages (-core and -modules) packages additionally to those already built out of the SRPM. Aside from the obvious changes to the package spec file, that includes evaluating what modules need to go into which package and making sure updating from pre-split kernel packages works as expected. Most of this work has already been done and can be found in rawhide by now.

Other developers: Anaconda must allow to install kernel-core instead of kernel, when using a kickstart file. (To gain full benefits of this change, but the change itself can be implemented without). Work has been done but is not well tested yet: https://bugzilla.redhat.com/show_bug.cgi?id=1074522

Release engineering: No changes necessary.

Policies and guidelines: No changes necessary.

Upgrade/compatibility impact

Full compatibility and upgrade-support. No noticeable impact. Systems with pre-split kernel packages will install the new kernel meta-package which in turn will install kernel-core and kernel-modules. All three together are equal to the pre-split kernel package.

How To Test

Updating from F20 to F21 (or any pre-split kernel to any post-split kernel) should work as expected, i.e. kernel, kernel-core and kernel-modules should be installed and be booted by default.
In virtualized environments (including clouds) only installing kernel-core but no kernel and kernel-modules should suffice to work as expected.
If only kernel-core but not kernel is installed, yum (and dnf) should install updates instead of updating the package. The same should still be true for the kernel package, if installed.
The kernel should work as expected, i.e. the usual kernel tests should be performed.
It must be possible to remove kernel and kernel-modules (and leaving only kernel-core).
It must be possible to install kernel and kernel-modules (if only kernel-core was installed).
Anaconda should somehow allow to install only kernel-core instead of kernel, through kickstart.
Make sure whatever you expect from your kernel that worked before, still works.

User Experience

Two more packages will be installed (visible in yum/dnf and rpm), but no noticeable change otherwise.

Dependencies

To gain the full benefits of this change, Anaconda needs to support installing kernel-core only (i.e. instead of kernel). But the kernel split itself is not depending on that and still useful otherwise.

Contingency Plan

Contingency mechanism:
- The kernel-split could be reverted, if really necessary. But as this work is nearly finished and the standard use cases are not impacted, it's unlikely we'll need to take this step. Either way, this shouldn't matter to any other packages.
- If support in anaconda for kernel-core is not ready in time, it should ship without it. The main change would not be affected by this.
Contingency deadline: Beta Freeze
Blocks release? No.
Blocks product? No.

Documentation

See Release Notes (below).

Release Notes

Starting with Fedora 21, the kernel package has been split up into three: kernel, kernel-core and kernel-modules. Now, the kernel package is merely a meta-package making sure that both kernel-core and kernel-modules are installed. This way, updates from a pre-split kernel will work as expected. Also, kernel is still the package that is installed by default, ensuring kernel-core and kernel-modules both are installed, too.
Running in virtualized environments, kernel-core alone should suffice, thus allowing e.g. for a smaller cloud image footprint. In all other cases kernel-modules should additionally be installed, too.
Please note, that a new initramfs is only automatically generated by the kernel-core package but not the kernel-modules package. If you only installed kernel-core at first and install kernel-modules at a later point in time, you need to create a new initramfs manually using dracut, if any of the newly installed modules has become critical for your system's boot up.

@@ Line 1: / Line 1: @@
-{{admon/important | Comments and Explanations | The page source contains comments providing guidance to fill out each section. They are invisible when viewing this page. To read it, choose the "edit" link.<br/> '''Copy the source to a ''new page'' before making changes!  DO NOT EDIT THIS TEMPLATE FOR YOUR CHANGE PROPOSAL.'''}}
+= Modular Kernel Packaging for Cloud =
-<!-- Self Contained or System Wide Change Proposal?
-Use this guide to determine to which category your proposed change belongs to.
-Self Contained Changes are:
-* changes to isolated/leaf package without the impact on other packages/rest of the distribution
-* limited scope changes without the impact on other packages/rest of the distribution
-* coordinated effort within SIG with limited impact outside SIG functional area, accepted by the SIG
-System Wide Changes are:
-* changes that does not fit Self Contained Changes category touching
-* changes that require coordination within the distribution (for example mass rebuilds, release engineering or other teams effort etc.)
-* changing system defaults
-For Self Contained Changes, sections marked as "REQUIRED FOR SYSTEM WIDE CHANGES" are OPTIONAL but FESCo/Wrangler can request more details (especially in case the change proposal category is
-improper or updated to System Wide category). For System Wide Changes all fields on this form are required for FESCo acceptance (when applies).
-We request that you maintain the same order of sections so that all of the change proposal pages are uniform.
--->
-<!-- The actual name of your proposed change page should look something like: Changes/Your_Change_Proposal_Name.  This keeps all change proposals in the same namespace -->
-= Change Proposal Name <!-- The name of your change proposal --> =
 == Summary ==
-<!-- A sentence or two summarizing what this change is and what it will do. This information is used for the overall changeset summary page for each release. -->
+Kernel modules that are not necessary in virtualized environments become optionally (un)installable.
 == Owner ==
@@ Line 32: / Line 9: @@
 This should link to your home wiki page so we know who you are.
 -->
-* Name: [[User:FASAcountName| Your Name]]
+* Name: Cloud SIG / [[User:red|Sandro Mathys]], Kernel Team / [[User:jwboyer|Josh Boyer]]
-<!-- Include you email address that you can be reached should people want to contact you about helping with your change, status is requested, or technical issues need to be resolved. If the change proposal is owned by a SIG, please also add a primary contact person. -->
+* Email: red@fedoraproject.org, jwboyer@fedoraproject.org
-* Email: <your email address so we can contact you, invite you to meetings, etc.>
+<!--- To be assigned by docs team [[User:FASAccountName| Release notes owner name]] <email address> -->
-* Release notes owner: <!--- To be assigned by docs team [[User:FASAccountName| Release notes owner name]] <email address> -->
 <!--- UNCOMMENT only for Changes with assigned Shepherd (by FESCo)
 * FESCo shepherd: [[User:FASAccountName| Shehperd name]] <email address>
 -->
-<!--- UNCOMMENT only if this Change aims specific product, working group (Cloud, Workstation, Server, Base, Env & Stacks)
+* Product: All Cloud products
-* Product:
+* Responsible WG: Cloud
-* Responsible WG:
--->
 == Current status ==
-* Targeted release: [[Releases/<number> | Fedora <number> ]]
+* Targeted release: [[Releases/21 | Fedora 21 ]]
-* Last updated: (DATE)
+* Last updated: 2014-03-13
 <!-- After the change proposal is accepted by FESCo, tracking bug is created in Bugzilla and linked to this page
 Bugzilla states meaning as usual:
@@ Line 55: / Line 29: @@
 CLOSED as NEXTRELEASE -> change is completed and verified and will be delivered in next release under development
 -->
-* Tracker bug: <will be assigned by the Wrangler>
+* Tracker bug: [https://bugzilla.redhat.com/show_bug.cgi?id=1081581 #1081581]
 == Detailed Description ==
 <!-- Expand on the summary, if appropriate.  A couple sentences suffices to explain the goal, but the more details you can provide the better. -->
+Space is precious in the cloud, therefore the Cloud SIG tries to keep the images' footprint as small as reasonably possible. Therefore, we'd like to split the kernel into two (plus one meta) packages. One package would contain the core modules, i.e. a minimum(-ish) set of modules to only just be able to run in virtualized environments. And another package for the rest. The 'kernel' package would then become a meta package that installs both (-core and -modules).
 == Benefit to Fedora ==
-<!-- What is the benefit to the platform?  If this is a major capability update, what has changed?  If this is a new functionality, what capabilities does it bring? Why will Fedora become a better distribution or project because of this proposal?-->
+* Possibility to install Fedora with a smaller footprint.
+* Official Fedora cloud images will become smaller.
+* Possibility to avoid respinning images for security updates if issue is in a driver not included in kernel core
 == Scope ==
-<!-- What work do the developers have to accomplish to complete the change in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
+Normal installations will continue installing the kernel (meta-)package and users should not notice any difference. Same goes for updating from earlier Fedora releases. But where desired, it should become possible to install only a reasonably minimal subset of kernel modules. Both kernel and kernel-core will Provide "kernel", therefore the "install instead of update" magic of yum/dnf will work as expected even if only kernel-core is installed.
-* Proposal owners:
+* Proposal owners: The kernel package needs to be changed to produce a meta- (kernel) and two new packages (-core and -modules) packages additionally to those already built out of the SRPM. Aside from the obvious changes to the package spec file, that includes evaluating what modules need to go into which package and making sure updating from pre-split kernel packages works as expected. Most of this work has already been done and can be found in rawhide by now.
-<!-- What work do the feature owners have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
-* Other developers: N/A (not a System Wide Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Other developers: Anaconda must allow to install kernel-core instead of kernel, when using a kickstart file. (To gain full benefits of this change, but the change itself can be implemented without). Work has been done but is not well tested yet: https://bugzilla.redhat.com/show_bug.cgi?id=1074522
-<!-- What work do other developers have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
-* Release engineering: N/A (not a System Wide Change)  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Release engineering: No changes necessary.
-<!-- Does this feature require coordination with release engineering (e.g. changes to installer image generation or update package delivery)?  Is a mass rebuid required?  If a rel-eng ticket exists, add a link here.  -->
-* Policies and guidelines: N/A (not a System Wide Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Policies and guidelines: No changes necessary.
-<!-- Do the packaging guidelines or other documents need to be updated for this feature?  If so, does it need to happen before or after the implementation is done?  If a FPC ticket exists, add a link here. -->
 == Upgrade/compatibility impact ==
-<!-- What happens to systems that have had a previous versions of Fedora installed and are updated to the version containing this change? Will anything require manual configuration or data migration? Will any existing functionality be no longer supported? -->
+Full compatibility and upgrade-support. No noticeable impact. Systems with pre-split kernel packages will install the new kernel meta-package which in turn will install kernel-core and kernel-modules. All three together are equal to the pre-split kernel package.
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-N/A (not a System Wide Change)
 == How To Test ==
-<!-- This does not need to be a full-fledged document. Describe the dimensions of tests that this change implementation is expected to pass when it is done.  If it needs to be tested with different hardware or software configurations, indicate them.  The more specific you can be, the better the community testing can be.
+* Updating from F20 to F21 (or any pre-split kernel to any post-split kernel) should work as expected, i.e. kernel, kernel-core and kernel-modules should be installed and be booted by default.
+* In virtualized environments (including clouds) only installing kernel-core but no kernel and kernel-modules should suffice to work as expected.
-Remember that you are writing this how to for interested testers to use to check out your change implementation - documenting what you do for testing is OK, but it's much better to document what *I* can do to test your change.
+* If only kernel-core but not kernel is installed, yum (and dnf) should install updates instead of updating the package. The same should still be true for the kernel package, if installed.
+* The kernel should work as expected, i.e. the usual kernel tests should be performed.
-A good "how to test" should answer these four questions:
+* It must be possible to remove kernel and kernel-modules (and leaving only kernel-core).
+* It must be possible to install kernel and kernel-modules (if only kernel-core was installed).
-. What special hardware / data / etc. is needed (if any)?
+* Anaconda should somehow allow to install only kernel-core instead of kernel, through kickstart.
-. How do I prepare my system to test this change? What packages
+* Make sure whatever you expect from your kernel that worked before, still works.
-need to be installed, config files edited, etc.?
-. What specific actions do I perform to check that the change is
-working like it's supposed to?
-. What are the expected results of those actions?
--->
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-N/A (not a System Wide Change)
 == User Experience ==
-<!-- If this change proposal is noticeable by its target audience, how will their experiences change as a result?  Describe what they will see or notice. -->
+Two more packages will be installed (visible in yum/dnf and rpm), but no noticeable change otherwise.
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-N/A (not a System Wide Change)
 == Dependencies ==
-<!-- What other packages (RPMs) depend on this package?  Are there changes outside the developers' control on which completion of this change depends?  In other words, completion of another change owned by someone else and might cause you to not be able to finish on time or that you would need to coordinate?  Other upstream projects like the kernel (if this is not a kernel change)? -->
+To gain the full benefits of this change, Anaconda needs to support installing kernel-core only (i.e. instead of kernel). But the kernel split itself is not depending on that and still useful otherwise.
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-N/A (not a System Wide Change)
 == Contingency Plan ==
-<!-- If you cannot complete your feature by the final development freeze, what is the backup plan?  This might be as simple as "Revert the shipped configuration".  Or it might not (e.g. rebuilding a number of dependent packages).  If you feature is not completed in time we want to assure others that other parts of Fedora will not be in jeopardy.  -->
+* Contingency mechanism:
-* Contingency mechanism: (What to do?  Who will do it?) N/A (not a System Wide Change)  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+** The kernel-split could be reverted, if really necessary. But as this work is nearly finished and the standard use cases are not impacted, it's unlikely we'll need to take this step. Either way, this shouldn't matter to any other packages.
-<!-- When is the last time the contingency mechanism can be put in place?  This will typically be the beta freeze. -->
+** If support in anaconda for kernel-core is not ready in time, it should ship without it. The main change would not be affected by this.
-* Contingency deadline: N/A (not a System Wide Change)  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Contingency deadline: Beta Freeze
 <!-- Does finishing this feature block the release, or can we ship with the feature in incomplete state? -->
-* Blocks release? N/A (not a System Wide Change), Yes/No <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Blocks release? No.
-* Blocks product? product <-- Applicable for Changes that blocks specific product release/Fedora.next -->
+* Blocks product? No.
 == Documentation ==
-<!-- Is there upstream documentation on this change, or notes you have written yourself?  Link to that material here so other interested developers can get involved. -->
+See Release Notes (below).
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-N/A (not a System Wide Change)
 == Release Notes ==
-<!-- The Fedora Release Notes inform end-users about what is new in the release.  Examples of past release notes are here: http://docs.fedoraproject.org/release-notes/ -->
+Starting with Fedora 21, the kernel package has been split up into three: kernel, kernel-core and kernel-modules. Now, the kernel package is merely a meta-package making sure that both kernel-core and kernel-modules are installed. This way, updates from a pre-split kernel will work as expected. Also, kernel is still the package that is installed by default, ensuring kernel-core and kernel-modules both are installed, too.
-<!-- The release notes also help users know how to deal with platform changes such as ABIs/APIs, configuration or data file formats, or upgrade concerns.  If there are any such changes involved in this change, indicate them here.  A link to upstream documentation will often satisfy this need.  This information forms the basis of the release notes edited by the documentation team and shipped with the release.
+<br/>
+Running in virtualized environments, kernel-core alone should suffice, thus allowing e.g. for a smaller cloud image footprint. In all other cases kernel-modules should additionally be installed, too. <br/>
-Release Notes are not required for initial draft of the Change Proposal but has to be completed by the Change Freeze.
+Please note, that a new initramfs is only automatically generated by the kernel-core package but not the kernel-modules package. If you only installed kernel-core at first and install kernel-modules at a later point in time, you need to create a new initramfs manually using dracut, if any of the newly installed modules has become critical for your system's boot up.
--->
-[[Category:ChangePageIncomplete]]
+[[Category:ChangeAcceptedF21]]
 <!-- When your change proposal page is completed and ready for review and announcement -->
 <!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler -->
@@ Line 142: / Line 95: @@
 <!-- Select proper category, default is Self Contained Change -->
-[[Category:SelfContainedChange]]
+<!-- [[Category:SelfContainedChange]] -->
-<!-- [[Category:SystemWideChange]] -->
+[[Category:SystemWideChange]]

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