Synnefo » snf-ganeti

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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