Developer notes
===============

.. highlight:: shell-example

Build dependencies
------------------

Most dependencies from :doc:`install-quick`, plus (for Python):

- `GNU make <http://www.gnu.org/software/make/>`_
- `GNU tar <http://www.gnu.org/software/tar/>`_
- `Gzip <http://www.gnu.org/software/gzip/>`_
- `pandoc <http://johnmacfarlane.net/pandoc/>`_
- `python-sphinx <http://sphinx.pocoo.org/>`_
  (tested with version 0.6.1)
- `graphviz <http://www.graphviz.org/>`_
- the `en_US.UTF-8` locale must be enabled on the system
- `pylint <http://www.logilab.org/857>`_ and its associated
  dependencies
- `pep8 <https://github.com/jcrocholl/pep8/>`_

Note that for pylint, at the current moment the following versions
must be used::

    $ pylint --version
    pylint 0.21.1,
    astng 0.20.1, common 0.50.3

To generate unittest coverage reports (``make coverage``), `coverage
<http://pypi.python.org/pypi/coverage>`_ needs to be installed.

For Haskell development, again all things from the quick install
document, plus:

- `haddock <http://www.haskell.org/haddock/>`_, documentation
  generator (equivalent to epydoc for Python)
- `HsColour <http://hackage.haskell.org/package/hscolour>`_, again
  used for documentation (it's source-code pretty-printing)
- `hlint <http://community.haskell.org/~ndm/hlint/>`_, a source code
  linter (equivalent to pylint for Python), recommended version 1.8 or
  above (tested with 1.8.15)
- the `QuickCheck <http://hackage.haskell.org/package/QuickCheck>`_
  library, version 2.x
- ``hpc``, which comes with the compiler, so you should already have
  it
- `shelltestrunner <http://joyful.com/shelltestrunner>`_, used for
  running unit-tests

Under Debian Wheezy or later, these can be installed (on top of the
required ones from the quick install document) via::

  $ apt-get install libghc-quickcheck2-dev hscolour hlint

Or alternatively via ``cabal``::

  $ cabal install quickcheck hscolour hlint shelltestrunner


Configuring for development
---------------------------

Run the following command (only use ``PYTHON=...`` if you need to use a
different python version)::

  $ ./autogen.sh && \
    ./configure --prefix=/usr/local --sysconfdir=/etc --localstatedir=/var

Note that doing development on a machine which already has Ganeti
installed is problematic, as ``PYTHONPATH`` behaviour can be confusing
(see Issue 170 for a bit of history/details; in general it works if
the installed and developed versions are very similar, and/or if
PYTHONPATH is customised correctly). As such, in general it's
recommended to use a "clean" machine for ganeti development.

Haskell development notes
-------------------------

There are a few things which can help writing or debugging the Haskell
code.

You can run the Haskell linter :command:`hlint` via::

  $ make hlint

This is not enabled by default (as the htools component is
optional). The above command will generate both output on the terminal
and, if any warnings are found, also an HTML report at
``doc/hs-lint.html``.

When writing or debugging TemplateHaskell code, it's useful to see
what the splices are converted to. This can be done via::

  $ make HEXTRA="-ddump-splices"

Due to the way TemplateHaskell works, it's not straightforward to
build profiling code. The recommended way is to run ``make hs-prof``,
or alternatively the manual sequence is::

  $ make clean
  $ make htools/htools HEXTRA="-osuf .o"
  $ rm htools/htools
  $ make htools/htools HEXTRA="-osuf .prof_o -prof -auto-all"

This will build the binary twice, per the TemplateHaskell
documentation, the second one with profiling enabled.


Packaging notes
===============

Ganeti is mostly developed and tested on `Debian
<http://www.debian.org/>`_-based distributions, while still keeping
adaptability to other Linux distributions in mind.

The ``doc/examples/`` directory contains a number of potentially useful
scripts and configuration files. Some of them might need adjustment
before use.

``daemon-util``
---------------

This script, in the source code as ``daemons/daemon-util.in``, is used
to start/stop Ganeti and do a few other things related to system
daemons. It is recommended to use ``daemon-util`` also from the system's
init scripts. That way the code starting and stopping daemons is shared
and future changes have to be made in only one place.

``daemon-util`` reads extra arguments from variables (``*_ARGS``) in
``/etc/default/ganeti``. When modifying ``daemon-util``, keep in mind to
not remove support for the ``EXTRA_*_ARGS`` variables for starting
daemons. Some parts of Ganeti use them to pass additional arguments when
starting a daemon.

The ``reload_ssh_keys`` function can be adjusted to use another command
for reloading the OpenSSH daemon's host keys.

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