Liquidsoap dev : Custom loading path

Basics

Starting with version 1.0.1, it is possible to build a liquidsoap binary that can load all its dependencies from any arbitrary path. This is very useful to distribute a liquidsoap bundled binary, independent of the distribution used.

You can enable custom path at configure time, by passing the --enable-custom-path configuration option. A custom loading path is a directory that contains the following file/directories:

• ./camomile: Camomile shared data. They are usually located in /usr/(local/)share/camomile
• ./libs: pervasive scripts. Their are located in liquidsoap/scripts in liquidsoap's sources
• ./log: default log directories
• ./magic: directory for magic files. See below for more details.
• ./plugins: default plugins directory (most likely empty)
• ./run: default runtime files directory

Adding liquidsoap binary

In order to ship a liquidsoap binary which is independent of the distribution it will be run on, one need to also include its dynamic libraries, except for the most common. The following command may be used to list them:

ldd ./liquidsoap | grep usr | cut -d' ' -f 3

Those libraries are usually copied into a ./ld directory. Then, the LD_LIBRARY_PATH is used to point the dynamic loader to this directory.

Finally, the liquidsoap library is usually added in ./bin/liquidsoap

Configuration variables

In the following, configuration variables may refer to either absolute or relative paths. If referring to a relative path, the path is resolved relatively to the directory where the liquidsoap binary is located at.

In order to tell liquidsoap where its custom path is located, you need to set the LIQUIDSOAP_BASE_DIR.

Another important variable is MAGIC. It tells liquidsoap where to load the libmagic's definitions and defaults to ../magic/magic.mgc. Older versions of libmagic may require to use magic/magic.mime instead.

Full example

For a fully-functional example, you can check our heroku buildpack. Its layout is:

./bin
./bin/liquidsoap
./camomile
./camomile/charmaps
(...)
./ld
./ld/libao.so.2
(...)
./libs
./libs/externals.liq
(...)
./log
./magic
./magic/magic.mime
./plugins
./run

Its configuration variables are set to:

LD_LIBRARY_PATH=/path/to/ld
LIQUIDSOAP_BASE_DIR=..
MAGIC=../magic/magic.mime

As you can see, we use an old version of libmagic so we need to load magic.mime instead of magic.mgc.