View source for Changes/Patches in Forge macros - Auto macros - Detached rpm changelogs

= Patches in Forge macros - Auto macros - Detached rpm changelogs =

== Summary ==

redhat-rpm-config will be updated to add patching support to forge macros, a plug-able framework to register macros to execute in specific sections, and rpm changelogs in detached files.

== Owner ==

* Name: [[User:nim| Nicolas Mailhot]]

* Email: <nicolas.mailhot at laposte.net>

== Current status ==
[[Category:ChangeAnnounced]]
<!-- When your change proposal page is completed and ready for review and announcement -->
<!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler -->
<!-- The Wrangler announces the Change to the devel-announce list and changes the category to Category:ChangeAnnounced (no action required) --> 
<!-- After review, the Wrangler will move your page to Category:ChangeReadyForFesco... if it still needs more work it will move back to Category:ChangePageIncomplete-->

<!-- Select proper category, default is Self Contained Change -->
[[Category:SystemWideChange]]
<!-- [[Category:SystemWideChange]] -->

* Targeted release: [[Releases/33 | Fedora 33 ]] 
* Last updated: <!-- this is an automatic macro — you don't need to change this line -->  {{REVISIONYEAR}}-{{REVISIONMONTH}}-{{REVISIONDAY2}} 

* FESCo issue: <will be assigned by the Wrangler>
* Tracker bug: <will be assigned by the Wrangler>
* Release notes tracker: <will be assigned by the Wrangler>

== Detailed Description ==

This is a system-wide change because all packages build with redhat-rpm-config, but it only concerns packages that opted to use this part of redhat-rpm-config (users of forge, fonts and go macros).

It was driven first, by the need to make the underlying macro infrastructure robust enough to package Go modules, and second, by an unfortunate rpm 4.15 regression that proved it was foolish to depend on rpmbuild to parse Tags in anything except canonical order.

=== Fully automated packaging ===

A framework was added so macro subsystems can register execution blocks in specific parts or the spec file. Execution blocks are orchestrated (using KISS rules) so for example the forge part of %prep is executed before the go parts that depend on forge archives being unpacked and patched, and macros that want to create srpm headers are executed before macros that want to create subpackage headers.

Such a framework is a requirement to control the generation order within the spec file and make sure rpm maintainers are not cross with you.

The macro execution plan is printed while it is being executed so the packager is not left wondering what the hell rpmbuild is doing (especially when syntax mistakes result in rpmbuild aborting with unhelpful error messages, or when rpmbuild breaks additive processing by executing the preamble multiple times without clearing state between executions).

`rpmspec -P` allows checking the generated spec and markers were added to this spec to show the execution block that generated a particular part of the spec (in all rpm sections that allow comments).

That means a spec with no special custom processing is reduced to a set of %global control variables that activate specific execution blocks, and absent custom processing needs, everything bellow those control variables is short and unchanging boilerplate.

A packager that needs custom processing can add custom code above or bellow the various `%auto_foo` calls, and check with `rpmspec -P` that the result does what he wants it to do. For obvious reliability reasons injecting custom code in the middle of an `%auto_foo` sequence is not allowed.

<pre>
%global source_name …
%global source_release …
%global source_post_release …
    
%global forge_url0 …
%global forge_commit0 …
    
%global forge_url1 …
%global forge_tag1 …
    
%global go_module33 …
%global go_description33 …
    
%global font_family22 …
%global font_conf22 …
    
%auto_init
%auto_pkg
    
%sourcelist
%auto_sources
    
%patchlist
%auto_patches
    
%prep
%auto_prep
    
%generate_buildrequires
%auto_generate_buildrequires
    
%build
%auto_build
    
%install
%auto_install
    
%check
%auto_check
    
%auto_files
    
%changelog
%auto_changelog
</pre>

=== Forge ===

* the forge macros now process patches, including when the spec contains multiple forge sources, in a natural way
* all dependencies on source/patch numbering were eradicated, you can write a whole multi-source/multi-patch spec without worrying about source or patch numbers

<pre>
%forge_urlX …
%forge_tagX …
%forge_patchlistX %{expand:
foo.patch
bar.patch
whatever.patch
}

%forge_urlY …
%forge_commitY …
%forge_patchlistY %{expand:
another.patch
}
</pre>

* zero suffix is no longer special (freeing the packager from Source/Source0/%setup numbering problems), you can declare forge blocks starting at 42 if that‘s your preference

* explicit %forgemeta, %forgesource, %forgesetup, etc calls are no longer needed, the corresponding execution blocks are registered in the %auto_call framework and will be executed by  %auto_init %auto_sources, %auto_patches and %auto_prep as needed, without requiring any forge-specific boilerplate.

* thus, forge macros use is now streamlined and (absent patching) reduced to a list of two-line declarations, suffixed with a number (X and y in the following example)

<pre>
%forge_urlX …
%forge_commitX …
    
%forge_urlY …
%forge_tagY …

%auto_init

%sourcelist
%auto_sources

%patchlist
%auto_patches

%prep
%auto_prep
</pre>

=== Automated SRPM header creation ===

The automation framework was used to implement a buildsys subsystem, charged with creating SRPM headers as needed, and controlling the SRPM evr. A future evolution of this subsystem is expected to make packages autobump without external help.

https://fedoraproject.org/wiki/Changes/rpm_level_auto_release_and_changelog_bumping

=== Detached changelogs ===

The buildsys subsystem was used to implement detached changelogs in a reliable way

A future evolution of this subsystem is expected to make changelogs autobump without external help.

=== Generic -doc creation ===

The automation framework was used to implement a doc subsystem, charged with -doc subpackage creation, because creating documentation subpackages by hand gets annoying after the nth upstream that wants you do distribute heavy PDF files.

=== Huge refactoring and fleshing out of the fedora lua library ===

Writing high-level features like the above required defining a library of lua routines like an expand that expands fully, an unset that actually undefines, a read that does not think an empty variable is the same thing as an unset variable, a `fedora.echo()` wrapper around `rpm.expand("%{echo:%{expand:" .. text .. "}}")`, etc. Those are now available for others to make use of should they want to.

Designing APIs is hard and I make no claim that the result is perfect, just that is it more convenient and less tricky that the raw low level calls rpm exposes in its own rpm lua library.

=== Drawbacks ===

Nothing is free, and a higher level of automation required using rigid naming for control variables. Because software is a lot less tolerant of fuzzy naming than human beings.

So, all forge control variables are renamed, fonts control variables have been renamed too, and go control variables will need renaming (in that last case, that’s not a problem because moving to go modules requires reworking variables anyway, so it will be done as part of the module effort in F34).

To ease the transition a compatibility layer was added to forge macros so old variables and new variables are aliased both ways (this will eventually go away because it’s quite a lot of compatibility code to maintain). Mixing syntaxes (old and new) is not supported, you need to convert your spec file to new forge variables or not at all (if not at all, do not try to use new features like patching).

== Feedback ==

<!-- Summarize the feedback from the community and address why you chose not to accept proposed alternatives. This section is optional for all change proposals but is strongly suggested. Incorporating feedback here as it is raised gives FESCo a clearer view of your proposal and leaves a good record for the future. If you get no feedback, that is useful to note in this section as well. For innovative or possibly controversial ideas, consider collecting feedback before you file the change proposal. -->

== Benefit to Fedora ==

Spec files that do more with less manual expensive to maintain spec code.

Without this productivity win, complex efforts like converting Fedora Go packages to Go modules, or draining the Font packages swamp given that legacy formats are no longer supported by apps, are not possible with the current level of Fedora manpower.

== Scope ==
* Proposal owners: the core of the feature is done and tested (and retested). It may evolve during the redhat-rpm-config merge process. https://src.fedoraproject.org/rpms/redhat-rpm-config/pull-request/95

* Other developers: the way current forge macros call forge macros will need a little patching once the change lands. For other packagers, there should be no change except a warning in rpm build logs to switch to the new syntax before the compatibility layer is removed.

* Release engineering: https://pagure.io/releng/issue/9565

* FPC: https://pagure.io/packaging-committee/issue/997

* Policies and guidelines: Forge guidelines will need some rework (mostly simplification, because the new syntax is both more powerful and more regular). For the average packager, the new syntax is the same old syntax with little naming adjustments.

* Trademark approval: N/A (not needed for this Change)
<!-- If your Change may require trademark approval (for example, if it is a new Spin), file a ticket ( https://fedorahosted.org/council/ ) requesting trademark approval from the Fedora Council. This approval will be done via the Council's consensus-based process. -->

== Upgrade/compatibility impact ==

This is a pure build tooling update, it changes how things are built not what is built.

== How To Test ==

A redhat-rpm-config packages with the changes and some example packages are available in 

* https://copr.fedorainfracloud.org/coprs/nim/refactoring-forge-patches-auto-call-changelog-fonts/builds/

The code itself is visible in

* https://src.fedoraproject.org/rpms/redhat-rpm-config/pull-request/95
* https://src.fedoraproject.org/fork/nim/rpms/redhat-rpm-config/commits/forge-with-patches-auto-call-auto-changelog-auto-srpm

== User Experience ==

N/A Packager experience change only

== Dependencies ==

The change depends on a redhat-rpm-config merge by redhat-rpm-config maintainers

== Contingency Plan ==

There is no contingency plan because the redhat-rpm-config merge will happen or not. If it does not happen, i18n, fonts and Go Changes that are/were envisioned for F33 or F34 will be postponed indefinitely.

== Documentation ==

There is as much documentation as the average redhat-rpm-config change (ie comments in the macro files themselves)

== Release Notes ==

N/A Packager productivity change only