Changes/Erlang 22

Erlang 22

Summary

Update Erlang/OTP to version 22.

Owner

• Name: Peter Lemenkov, Fedora Erlang SIG, Randy Barlow, Jeremy Cline
• Email: lemenkov@gmail.com, erlang@lists.fedoraproject.org, bowlofeggs@fedoraproject.org, jcline@fedoraproject.org
• Release notes ticket: TBA

Current status

• Targeted release: Fedora 31
• Last updated: 2019-07-16
• Tracker bug: #1739979
• Release Notes tracker: #375

Detailed Description

Upgrade Erlang to version 22 which brings a lot of changes. Just a few highlights:

• Better and faster compiler. Faster string operations which Elixir users will benefit.
• A new experimental low-level socket API.
• Even faster SSL/TLS operations.
• Improved Erlang Distribution Protocol handling when it comes to a huge messages (splitting into smaller ones, no longer blocking).

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

• Every daemon written in Erlang has its own logging solution which doesn't use neither syslog nor Journald. We should start switching them to Journald.
• We should add ability to use D-Bus via erlang-dbus library.
• Further improve Erlang Packaging Guidelines and promote it as the official guideline.
• Switch to rebar3 as a main build tool.

Benefit to Fedora

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

• Improved logging, better unified with the rest of system.

Scope

• Proposal owners:
  • Upgrade Erlang to the latest version (22.0).
  • We must rebuild every package which requires NIF version (listed below in the Dependencies section) against Erlang 22.x.y.
  • Every Erlang daemon's systemd unit must require epmd.socket.
  • We need to fill new review request for erlang-ejournald
    • We have to fill new review request for erlang-lager_journald_backend
  • We need to fill new review request for erlang-dbus
  • Upgrade outdated packages:
    • Riak
      • Riak has has been retired. We have to re-add it back.
    • Ejabberd
    • RabbitMQ.
    • CouchDB
  • rebar3
    • Provide/adjust RPM macros for rebar3.
  • Package GDB macros for easier coredump debugging (see also this ticket).
  • Enable Kerberos authentication in Ejabberd (finally).
• Other developers: N/A
• Release engineering: TBA
• Policies and guidelines:
  • We should promote officially Erlang Packaging Guidelines.
• Trademark approval: N/A (not needed for this Change)

Upgrade/compatibility impact

• Every Erlang upgrade requires the rebuilding of modules which contains ports or NIFs, and we will rebuild all such modules in Fedora. However if a user has some additional modules not available in a Fedora repository, then these modules must be rebuilt manually.
• So-called HiPE continues to deteriorate. In this version it's barely functional and likely is going to be removed in the next one.

How To Test

• Ensure that high-grade Erlang applications are still working:

Name	Tested
couchdb	No
ejabberd	No
elixir	No
mochiweb	No
rabbitmq-server	No
riak	No (package was retired :( )
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:

Name	Rebuilt
couchdb	No
erlang-basho_metrics	No
erlang-bitcask	No
erlang-cache_tab	No
erlang-cl	No
erlang-ebloom	No
erlang-eleveldb	No
erlang-emmap	No
erlang-erlsyslog	No
erlang-esasl	No
erlang-esdl	No
erlang-esip	No
erlang-fast_tls	No
erlang-fast_xml	No
erlang-fast_yaml	No
erlang-hyper	No
erlang-iconv	No
erlang-jiffy	No
erlang-js	No
erlang-lfe	No
erlang-riak_ensemble	No
erlang-sd_notify	No
erlang-skerl	No
erlang-snappy	No
erlang-stringprep	No
erlang-xmpp	No

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 Erlang R14, Erlang R15, Erlang R16, Erlang 17, Erlang 18, Erlang 19, Erlang 20, and Erlang 21). 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

• Erlang/OTP 22.0 release notes

Release Notes

Erlang/OTP 22.0 is available in Fedora 31.