.. _projectrefs:

The project.refs file
=====================
If one has elected to store source references in a single ``project.refs``
file, then it will be stored at the toplevel of your project directory
adjacent to ``project.conf``. This can be configured in your project
using the :ref:`ref-storage configuration <project_format_ref_storage>`

Sources for :mod:`junction <elements.junction>` elements are stored
separately in an adjacent ``junction.refs`` file of the same format.


.. _projectrefs_basics:

Basic behavior
--------------
When a ``project.refs`` file is in use, any source references found
in the :ref:`inline source declarations <format_sources>` are considered
invalid and will be ignored, and a warning will be emitted for them.

When ``bst track`` is run for your project, the ``project.refs`` file
will be updated instead of the inline source declarations. In the absence
of a ``project.refs`` file, ``bst track`` will create one automatically
with the tracking results.

An interesting property of ``project.refs`` is that it allows for
*cross junction tracking*. This is to say that it is possible to override
the *ref* of a given source in a project that your project depends on via
a :mod:`junction <elements.junction>`, without actually modifying the
junctioned project.


.. _projectrefs_format:

Format
------
The ``project.refs`` uses the same YAML format used throughout BuildStream,
and supports the same :ref:`directives <format_directives>` which apply to
``project.conf`` and element declaration files (i.e. *element.bst* files).

The ``project.refs`` file format itself is very simple, it contains a single ``projects``
key at the toplevel, which is a dictionary of :ref:`project names <project_format_name>`.
Each *project name* is a dictionary of *element names*, and each *element name* holds
a list of dictionaries corresponding to the element's :ref:`sources <format_sources>`.


**Example**

.. code:: yaml

   # Main toplevel "projects" key
   projects:

     # The local project's name is "core"
     core:

       # A dictionary of element names
       base/automake.bst:

       # A list of sources corresponding to the element
       # in the same order in which they were declared.
       #
       # The values of this list are dictionaries of the
       # symbolic "ref" portion understood by the given
       # source plugin implementation.
       #
       - ref: af6ba39142220687c500f79b4aa2f181d9b24e4...

     # The "core" project depends on the "bootstrap" project,
     # here we are allowed to override the refs for the projects
     # we depend on through junctions.
     bootstrap:

       zlib.bst:
       - ref: 4ff941449631ace0d4d203e3483be9dbc9da4540...