F37 proposal: Erlang 25 (Self-Contained Change proposal)

[Ben Cotton]

https://fedoraproject.org/wiki/Changes/Erlang_25

This document represents a proposed Change. As part of the Changes
process, proposals are publicly announced in order to receive
community feedback. This proposal will only be implemented if approved
by the Fedora Engineering Steering Committee.

== Summary ==
Update Erlang/OTP to version 25.

== Owner ==
* Name: [[User:Peter|Peter Lemenkov]], [[SIGs/Erlang|Fedora Erlang
SIG]], [[User:bowlofeggs|Randy Barlow]], [[User:jcline|Jeremy Cline]]
* Email: lemenkov(a)gmail.com, erlang(a)lists.fedoraproject.org,
bowlofeggs(a)fedoraproject.org, jcline(a)fedoraproject.org


== Detailed Description ==
Upgrade Erlang to version 25 which brings a lot of changes. Just a few
highlights [https://www.erlang.org/blog/my-otp-25-highlights/ from
many]:

* [https://www.erlang.org/blog/parallel-signal-sending-optimization/
The Many-to-One Parallel Signal Sending Optimization].
* [https://www.erlang.org/blog/type-based-optimizations-in-the-jit/
Type-Based Optimizations in the JIT].
* New 'maybe' operator.
* The JIT now supports the AArch64 (ARM64) architecture.
* Better support for perf and gdb.
* Better error reporting in some cases.


Aside from this, we plan to further improve quality of Erlang and
related packages. These are shortcomings we want to address:

* Finish switching to rebar3 as a main build tool and deprecate rebar2.
** Improve [[User:Peter/Erlang_Packaging_Guidelines|Erlang Packaging
Guidelines]] according to this switch and promote it as the official
guideline.
* Every daemon written in Erlang has its own logging solution which
doesn't use neither syslog nor Journald. We should start switching
them to unified logger.
* We should allow D-Bus API via [https://github.com/lizenn/erlang-dbus
erlang-dbus] library or any other recent implementations..
* SELinux rules for main Erlang applications (Ejabberd, CouchDB,
RabbitMQ) are still outdated or missing.

== Benefit to Fedora ==
Fedora users, both developers and end-users, will have visible
benefits from using Fedora-provided packages. Namely:

* Improved scalability and robustness.
* Much easier developing and debugging.

== Scope ==
* Proposal owners:
** [https://bugzilla.redhat.com/show_bug.cgi?id=2055490 Upgrade Erlang
to the latest version (25.0)].
** Every Erlang daemon's systemd unit should require epmd.socket.
** Upgrade outdated packages:
*** {{package|riak|Riak}}
**** {{package|riak|Riak}} has has been retired. We have to re-add it back.
*** {{package|ejabberd|Ejabberd}}
*** {{package|rabbitmq-server|RabbitMQ}}.
*** {{package|couchdb|CouchDB}}
**** {{package|riak|CouchDB}} has has been retired. We have to re-add it back.
** {{package|erlang-rebar3|rebar3}}
** Package GDB macros for easier coredump debugging (see also
[https://bugzilla.redhat.com/show_bug.cgi?id=663253 this ticket]).
* Other developers: N/A
* Release engineering: TBA
* Policies and guidelines:
** We should promote officially
[[User:Peter/Erlang_Packaging_Guidelines|Erlang Packaging
Guidelines]].
* Trademark approval: N/A (not needed for this Change)

== Upgrade/compatibility impact ==
* Binaries compiled with Erlang 22 and older are no longer compatible.

== How To Test ==

* Ensure that high-grade Erlang applications are still working:
{| border="1"
|-
| '''Name''' || '''Tested'''
|-
| {{package|couchdb}}  || {{no}} (package was retired :( )
|-
| {{package|ejabberd}} || {{no}}
|-
| {{package|elixir}} || {{no}}
|-
| {{package|rabbitmq-server}} || {{no}}
|-
| {{package|riak}} || {{no}} (package was retired :( )
|-
| {{package|wings}} || {{no}}
|}

* Collect feedback from volunteers regarding their experience with
this Erlang/OTP version

== User Experience ==
Users will get more robust, scalable, and fast Erlang applications.

== Dependencies ==

The following packages must be rebuilt: NIF-libraries.

== Contingency Plan ==
* Contingency mechanism: None necessary. Instead of falling back to
the previous version we should fix existing packages in order to help
the Community. We should also monitor upstream development process for
potentially discovered issues and proactively apply patches (as we
already did with [[Features/Erlang_R14|Erlang R14]],
[[Features/Erlang_R15|Erlang R15]], [[Features/Erlang_R16|Erlang
R16]], [[Changes/BetterErlangSupport|Erlang 17]],
[[Changes/Erlang_18|Erlang 18]], [[Changes/Erlang_19|Erlang 19]],
[[Changes/Erlang_20|Erlang 20]], [[Changes/Erlang_21|Erlang 21]],
[[Changes/Erlang_22|Erlang 22]], [[Changes/Erlang_23|Erlang 23]], and
[[Changes/Erlang_24|Erlang 24]]). It should be noted that this change
consists from an independent or loosely coupled smaller changes. If we
fail to deliver some changes in time, we should reschedule these exact
changes to the future Fedora release while keeping already implemented
ones.
* Contingency deadline: N/A
* Blocks release? N/A
* Blocks product? N/A

== Documentation ==
* [https://www.erlang.org/news/157 Erlang/OTP 25.0 release notes]

== Release Notes ==

Erlang/OTP 25.0 is available in Fedora 37.


-- 
Ben Cotton
He / Him / His
Fedora Program Manager
Red Hat
TZ=America/Indiana/Indianapolis