Liquidsoap can create a source that pulls its data from an HTTP location. This location can be a distant file or playlist, or an icecast or shoutcast stream.
To use it in your script, simply create a source that way:
This operator will pull regulary the given location for its data, so it should be used for locations that are assumed to be available most of the time. If not, it might generate unnecessary traffic and polute the logs. In this case, it is perhaps better to inverse the paradigm and use the input.harbor operator.