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Guide for volunteer eager to maintain legacy JDK/JRE in fedora

Originally proposed as system wide change, but suspended by lack of actual author. If one will step into the maintaining, then those rules will evolve from various proposals to suit all needs. For completness, here is huge discussion on devel: https://lists.fedoraproject.org/pipermail/devel/2015-February/208270.html


Legacy implementations of the Java platform in Fedora

Summary

Currently Fedora supports one main Java runtime and Java Development Kit (JDK) and from time to time one future JDK as a tech preview. This change should be set of rules, which will enable community to maintain legacy JDKs. Please note, people are bugging main JDK maintainers pretty often with this, and to allow them to maintain legacy JDKs is a step in right direction.

Owner

Current status

  • Targeted release: Fedora 22
  • Last updated: 2014-02-23
  • Tracker bug: <will be assigned by the Wrangler>

Detailed Description

This is no real work proposal. The result of this proposal is set of rules, which will allow community maintainers to pack any legacy jdk and will be ensuring that this JDKs will not conflict by any other JDK and will smoothly integrate to system. The results are summarized here, and pledged for discussion until final resolution is done.

Proposed rules

0. Main JDK maintainers are never ever responsible for any legacy jdk. This must remain clear

option one - introducing new packages - preferred

  1. main jdk is proclaimed as dead as it was until now. The new jdk is derived as new package prviousName-legacy
    1. so from killed java-1.7.0-openjdk will become new package java-1.7.0-openjdk-legacy
    2. next main jdk do Obsolete previous one as usually
  2. new package must not do any virtual provides (aka java,java-devel)... (protection against random pull by as dependence)
    1. it provides only itself by name
  3. Alternatives must be removed. If not, becasue JDK will stop work, then following must be kept:
    1. its priority must be kept on less digits (right now it would be 5) then main jdk (protection against winning in alternatives after update)
      1. the automated check as https://bugzilla.redhat.com/show_bug.cgi?id=1189084 are mandatory
      2. this 4 lines : http://pkgs.fedoraproject.org/cgit/java-1.8.0-openjdk.git/tree/java-1.8.0-openjdk.spec?id=fb001ce997e7fc95c1eeca02d3ed004dc59035a1#n956 from this patch: http://pkgs.fedoraproject.org/cgit/java-1.8.0-openjdk.git/commit/?id=fb001ce997e7fc95c1eeca02d3ed004dc59035a1 are god example
  4. at least one of the main-jdk's members must be set as comaintainer (to watch the commits and save the world if necessary)
  5. new package should to follow both original jdk (ideally not change at all (except source updates and necessary)) and current main jdk as close as possibly
    1. here it requires some common sense and a lot of testing if integration with system is as expected
  6. as it is generally not new package, the review process should be only formal - to know maintainer and to create cvs repo
    1. this is quite important, otherwise the new maintainer can become really frustrated, and we are forcing the "dead" package over"orpahned" so the full review (especially in alignment with rule 5) really should not be forced.
    2. on the contrary, rules agreed here must be checked. (even the number 5)
  7. all depending packages must keep requiring java-headless or java (and BuildRequires java-devel). Requirements on any exact jdk - or even worse on any exact legacy jdk are forbidden and needs FESCO exception.

This option is forcing maintainers to fight with the name x current setup of alternatives. However, the work should be minimal. But it makes the update path pretty clear and it keeps users well protected against legacy jdk.

option two - orphaning legacy jdks and ensure update path

  1. main JDK is only orphaned when new main JDK landed
    1. it do not Obsolate previous jdk
  2. other rules (2-7) are same

This is making life of legacy JDK maintainers a bit simpler. But...

But... To make this work properly with obsolete and update path, this requires metapacakges for each subpackage of openjdk, which have virtual provides and move those virtual provides to this metapackage (which requires real impl). See:

option three - out of regular Fedora

  1. Use https://fedorahosted.org/copr/ for your own dnf repo - http://dnf.baseurl.org/2014/03/19/copr-plugin/
  2. then all must above, are just recommendations but with positives/negatives of approach chosen

Benefit to Fedora

There do exists products being developed in Fedora, but targeted for third party. Those products may be targeted for different then Fedora's main JDK. Also there exists out of repo java applications which are bound to older JDK version. To make development of such a product more simple or running of those bounded apps easier, to have legacy JDKs directly in Fedora would be nice

Scope

  • Proposal owners: are responsible for initial setup of those guidelines.

The FESCO, the owners and pssible legacy JDKs maintainers have to agree on those rules. New legacy JDK can be then added anytime in Fedora lifecycle.

  • Other developers: no developers
  • Release engineering: in ideal case, no release engineer needed
  • Policies and guidelines: The proposal may split to proposal and "Legacy JDKs in Fedora guidelines" pages

Upgrade/compatibility impact

The result of this proposal should ensure, that upgrading users will not be non-volunteerly affected by legacy jdk

How To Test

not interested user

  • if you will not notice existence of legacy jdk in koji, the test passed

interested user

  • If you are able to install any legacy JDK by simple yum, and it works for you, then the test passed

User Experience

not interested user

  • update of Fedora will not keep legacy jdk on your system, or at least it will not be set as default
  • operations with packages will not lead to accidental install of legacy jdk (at least easily)
  • you will be able to remove legacy jdk without any complications
  • the packages stack will be run by main jdk

interested user

  • is able to install legacy jdks without any complications
    • is able to use them (also in parallel with regular one)
    • the packages stack will be run by main jdk (but not obligatory without manual interference)
    • you are able to use the legacy jdk for your work

Dependencies

  • No current package should depend on this proposal
  • future legacy JDKS are all depending on the result of proposal
  • packages which may depend on legacy jdk may appear in future, but have to attend

Contingency Plan

  • Contingency mechanism: The legacy JDKs must follow here agreed rules. Theirs not keeping may lead to ban package. However the existence of legacy JDK is not condition for existence of those rules. So no legacy jdk is also an success. Main JDK maintainers are never ever responsible for any legacy jdk. This must remian clear
  • Contingency deadline: Beta freeze
  • Blocks release? NO
  • Blocks product? NO

Documentation

This proposal itself is an documentation, unless it is split to proposal and guideline.

Release Notes

Release notes should be mentioning, that any legacy jdk which is coming with this Fedora is subject of those conditions.

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