===========================
plainbox-trusted-launcher-1
===========================

.. argparse::
    :ref: plainbox.impl.secure.launcher1.get_parser_for_sphinx
    :prog: plainbox-trusted-launcher-1
    :manpage:
    :nodefault:

    This command is a part of the implementation of :doc:`plainbox`. It is not
    intended to be invoked directly and the command line arguments and behavior
    may freely change between versions.

    Technically this program is used to run a command associated with a job
    definition as another user (typically as root). The existing technologies
    such as ``sudo`` (8) and ``pkexec`` (1) don't have enough granularity to
    still restrict arbitrary commands but allow the commands that are inside
    system-wide installed locations (thus safe as one needs root access to
    install those in the first place). One additional restriction is that some
    commands are themselves generated by other jobs.

    Execution
    =========

    Warm-up Mode
    ------------

    If the ``--warmup`` option is specified then nothing more happens and the
    program exists immediately. This is intended to 'warm-up' the tool that
    executes ``plainbox-trusted-launcher-1`` itself (typically ``pkexec`` or
    ``sudo``)

    Normal Execution
    ----------------

    In normal execution mode, the launcher looks up the job with the checksum
    specified by ``--target`` and executes the command embedded inside. Environment
    passed via ``--target-environment`` is appended to the environment variables
    inherited from the parent process.

    Standard output, standard error and exit code of
    ``plainbox-trusted-launcher-1`` is exactly as the values from the commands
    embedded into the selected job itself.

    Indirect Execution
    ------------------

    In indirect execution mode, the launcher first looks up the job with the
    checksum specified by ``--generator``, executes it, discarding stderr and
    re-interpreting stdout as a set of job definitions. Environment passed via the
    ``--generator-environment`` is appended (but just to the generator job, the
    ``--target`` job has independent environment). All of the additional job
    definitions are added to the global pool of jobs the launcher knows about.

    After that the launcher continues as with normal execution, returning the same
    stdout, stderr and exit code.

Environment Variables
=====================

The following environment variables *DO NOT* affect ``plainbox-trusted-launcher-1``

``PROVIDERPATH``
    For :doc:`plainbox` this would affect the set of directories where PlainBox
    looks for provider definitions. The trusted launcher has a fixed list of
    directories that cannot be extended.

    The fixed list is composed of two system-wide locations:

    * ``/usr/local/share/plainbox-providers-1``
    * ``/usr/share/plainbox-providers-1``

  All the other environment variables mentioned in :doc:`plainbox` work the
  same way.

Bugs
====

Currently it is impossible to use ``plainbox-trusted-launcher-1`` with a
``local`` job needs to run as root, that generates another ``local`` job that
needs to run as root, to generate any additional jobs that also need to run as
root. In other words, only one-level job generation is supported.

The launcher is somewhat inefficient, in that it has to re-run all of the
dependencies of the ``local`` job over and over. Ideally those would be cached,
per-session, but that would significantly increase the complexity of the code
running as root.

See Also
========

:doc:`plainbox`
