Changes/Erlang 21

Erlang 21

Summary

Update Erlang/OTP to version 21.

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 30
• Last updated: 2018-12-12
• Tracker bug: #1661637
• Release Notes tracker: #270

Detailed Description

Upgrade Erlang to version 21 which brings a lot of changes. Just a few highlights:

• The BEAM interpreter has been completely re-written.
• The compiler is about 10-20% faster.
• Enhanced and improved IO handling.
• All CORBA libraries were splitted off to independent repository.
• Insecure crypto algorithms were disabled.
• Non-smp VM removed.
• New API for logging, logger.
• The zlib module has been refactored and all its operations will now yield appropriately, allowing them to be used freely in concurrent applications.

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.
• Finish building noarch Erlang packages we've implemented previously.

Benefit to Fedora

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

• Even faster and smoother IO in Erlang.
• Improved logging, better unified with the rest of system.

Scope

• Proposal owners:
  • Upgrade Erlang to the latest version (21.2). DONE
  • We must rebuild every package which requires NIF version (listed below in the Dependencies section) against Erlang 21.x.y. DONE
  • 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
  • Finish building noarch Erlang packages we've implemented previously. DONE.
  • Upgrade outdated packages:
    • Riak
      • Riak has has been retired. We have to re-add it back.
    • Ejabberd
    • RabbitMQ. DONE. Upgraded to ver. 3.7.12.
    • CouchDB
  • Package rebar3 in a separate package. DONE
    • 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.
• Function erlang:get_stacktrace/0 was removed. Use the following approach to maintain compatibility.
• So-called tuple calls were removed.

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	Yes
erlang-basho_metrics	Yes
erlang-bitcask	Yes
erlang-cache_tab	Yes
erlang-cl	Yes
erlang-ebloom	Yes
erlang-eleveldb	Yes
erlang-emmap	Yes
erlang-erlsyslog	Yes
erlang-esasl	Yes
erlang-esdl	Yes
erlang-esip	Yes
erlang-fast_tls	Yes
erlang-fast_xml	Yes
erlang-fast_yaml	Yes
erlang-hyper	Yes
erlang-iconv	Yes
erlang-jiffy	Yes
erlang-js	Yes
erlang-lfe	Yes
erlang-riak_ensemble	Yes
erlang-sd_notify	Yes
erlang-skerl	Yes
erlang-snappy	Yes
erlang-stringprep	Yes
erlang-xmpp	Yes

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, and Erlang 20). 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 21.0 release notes
• Erlang/OTP 21.1 release notes
• Erlang/OTP 21.2 release notes
• Erlang/OTP 21.3 release notes

Release Notes

Erlang/OTP 21.2 is available in Fedora 30.