Expose config param to allow specific libsass commit for build

[nschonni]

Although we ship prebuilt binaries, it may be beneficial to allow users to rebuild their own bindings to a specific version of libsass. The use case I'm seeing with this is for those that want the latest libsass, but not require us to re-release and prep for a non-tagged libsass release.

Maybe something like this in the package.config

{
...
  "libsass": "commitHash"
}

I lean towards a config value rather than a .node-sass.yml, although that would be a valid approach too.

@andrew thoughts?

[andrew]

I like the sound of that, I prefer the package.json config option myself.

[keithamus]

+1 for package.json

[am11]

At present, if end-user wants to get the binary out of the desired libsass and given they have compiler GCC 4.6+ (or VC 2013+) and python v2.7 installed, they can:

1 - first install node-sass:

cd /tmp
npm install node-sass
cd node_modules/node-sass

# the following is to overcome the bug in v2.0.1, as pangyp (temporary fork of node-gyp
# supporting io.js) was mistakenly added as devDependency. This has been mitigated:
npm install pangyp

2 - then update upstream submodule:

cd src/libsass
git remote add libsass https://github.com/sass/libsass
git fetch libsass
git checkout <my-favourite-hash>
cd ../..

3 - rebuild binary:

node scripts/build --force
# force flag tells the script to ignore the presence of existing binary

Are we aiming to provision automating step 2 here; replacing <my-favourite-hash> with require('package').libsassHash (since libsass in now reserved for libsass version in our package.json)?

So user can do:

# pwd: node-sass root directory
nano package.json
# updated the value of libsassHash with desired hash, save and close editor, then
node scripts/build --force --update
# where --update would be the new flag which would tell the build script to: git checkout <hash>

[xzyfer]

I believe this use case has been addressed by the LIBSASS_EXT flag introduced in #763.

You can now supply the on disk location of the Libsass you wish to use with

LIBSASS_EXT=/path/to/libsass npm install node-sass

[saper]

There are two ways you can specify the external library:

LIBSASS_EXT=auto

to detect library using pkg-config

or

LIBSASS_EXT=yes
LIBSASS_CFLAGS=-I<path to sass.h header>
LIBSASS_LDFLAGS=-L<path to libsass.so or libsass.a library>
LIBSASS_LIBRARY=-lsass

For example:

LIBSASS_EXT=yes
LIBSASS_CFLAGS=-I/usr/local/include
LIBSASS_LDFLAGS=-L/usr/local/lib
LIBSASS_LIBRARY=-lsass