Date: Wed, 19 Jun 2013 16:01:41 +0200
From: Natanael Copa <ncopa@alpinelinux.org>
To: alpine-devel@lists.alpinelinux.org
Subject: [alpine-devel] upgrading to Lua 5.2
Message-ID: <20130619160141.25d3702e@ncopa-desktop.alpinelinux.org>
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Hi,

I have been looking at upgrading to Lua 5.2. Many things is just a
question of recompile and some needs porting.

So far, those have been rebuilt/ported against 5.2 in a local branch:
apache2
apk-tools
asterisk
awesome
gegl
graphviz
haserl
lsyncd
nmap
ntop
pingu
pllua
sircbot
vim
weechat

lua-augeas
lua-cjson
lua-filesystem
lua-microlight
lua-posix
lua-socket


I haven't verified if all of them runs.

Those failed and still need some work:

vlc
squark
rrdtool
lighttpd
kamailio
tolua++
conky
cegui06

Some of them looks non-trivial, like squark.

I asked in #lighttpd and there was some resistance from upstream to
port the stable lighttpd to lua 5.2 as it risks to break users scripts.


Then there are a bunch of modules that I have not yet looked at:
lua-cmsgpack
lua-curl
lua-dbi
lua-discount
lua-expat
lua-iconv
lua-imlib2
lua-ldap
lua-lgi
lua-llthreads
lua-md5
lua-openrc
lua-pc
lua-posixtz
lua-pty
lua-rex
lua-sec
lua-signal
lua-sleep
lua-sql-mysql
lua-sql-postgres
lua-sql-sqlite3
lua-stdlib
lua-stringy
lua-subprocess
lua-uuid
lua-xctrl
lua-xml
lua-yaml
lua-zlib
lua-zmq

I think some of those will just work, if they only gets installed in
proper dir. Some will require minimal a bit of porting.

Then we have the entire acf-*. I think it will be fairly easy to port
those. They are just many.

Now, I am still a bit in doubt how we move forward. I think we have the
following options:

One shot upgrade
================
We upgrade lua package to 5.2.x and port/upgrade everything in a
(local) git branch. Once everything is done we push. For things that is
difficult to port we can use luafiveq.

At that time evertying is over to Lua 5.2.

Benefits:
  once done, we save us for maintaining both lua 5.1 and 5.2 in
  parallel.

  We will only have one Lua.

Drawbacks:
  difficult to let many help in doing it. Until everything is done, the
  only lua version available will be lua 5.1. How are developers
  supposed to be able to help?

  Users will not be able to upgrade to alpine v2.7 until they are ready
  for Lua 5.2.

  We get same problem when 5.3 comes out.


One shot upgrade, with partial 5.1 compatibility
================================================
We upgrade lua to 5.2 and provide a lua5.1 package for backwards
compat. We could use luafiveq for those who are difficult to port and those who cannot use that either can rebuild against lua5.1-dev.

Benefits:
  less maintenance than supporting both. It gives developers a chance
  to get started to migrate to 5.2.

Drawbacks:
  We might need to support some of the modules (lua-*) both for 5.1 and
  for 5.2  for some time. We need rename all the 5.1 modules to lua5.1-*.

  Users will not be able to upgrade to alpine v2.7 until they are ready
  for Lua 5.2. (or have to manually install/change to use lua5.1 while
  upgrading)

  We get same problem when 5.3 comes out.


Append 5.2 and migrate slowly over
==================================
Add a new package named lua5.2. and rebuild the easy apps against
lua5.2. The package named 'lua' will still be lua-5.1. Ported/upgraded
modules will be be prefixed with 'lua5.2-'.

Benefits:
  we don't need big onetime commits which depends on one person or one
  big branch.

  Developers can install lua5.2 and start port stuff fairly early.

  Smoother upgrades for end users (hopefully). The packages are not
  suddenly renamed so local user scripts does not suddenly break.

  Might make it easier when 5.3 comes out since we can do similar then.
  At that time we can evaluate to delete the 5.1.

Drawbacks:
  Simply 'apk add lua' will give old lua so it kind of encourage
  endusers to stay on old which gives us more maintenance in the long
  run.

  We might not be able to have both 5.1 and 5.2 installed at the same
  time so it might cause more package conflicts. (what should
  /usr/bin/lua point to?)


Support both versions in parallel
=================================
Rename all current lua-* to lua5.1-* and rebuild all current against
that. Then add lua5.2 and port things slowly over. Support both as long
as it makes sense.

Benefits:
  Users can at any time choose 5.1 or 5.2 or have both installed at the
  same time.

  Developers can start port stuff and test on both.

  Makes a future 5.3 easier.

Drawbacks:
  Lots of work.

  More maintenance work. We might end up with +50 packages if not more.




What do you think? I think I'd prefer one of the 2 options in the middle.

In any case, porting to 5.2 will require pretty much work so I think
I'd like to get more people involved and start help with that as soon as
possible.


-nc


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