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# Developer notes

## Build dependencies

Most dependencies from Ganeti quick installation guide, including `qemu-img` (marked there as optional) plus (for Python):

- GNU make
- GNU tar
- Gzip
- pandoc
- python-epydoc
- python-sphinx (tested with version 1.1.3)
- graphviz
- the en_US.UTF-8 locale must be enabled on the system
- pylint and its associated dependencies
- pep8
- PyYAML

For older developement (Ganeti < 2.4) `docbook` was used instead `pandoc`.

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

    $ pylint --version
    pylint 0.25.1,
    astng 0.23.1, common 0.58.0

The same with pep8, other versions may give you errors:

    $ pep8 --version
    1.2

Both these versions are the ones shipped with Debian Wheezy.

To generate unittest coverage reports (`make coverage`), coverage needs to be installed.

Installation of all dependencies listed here:

    $ apt-get install python-setuptools automake git fakeroot
    $ apt-get install pandoc python-epydoc graphviz
    $ apt-get install python-yaml
    $ cd / && sudo easy_install \
              sphinx \
              logilab-astng==0.23.1 \
              logilab-common==0.58.0 \
              pylint==0.25.1 \
              pep8==1.2 \
              coverage

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

- haddock, documentation generator (equivalent to epydoc for Python)
- HsColour, again used for documentation (it’s source-code pretty-printing)
- hlint, a source code linter (equivalent to pylint for Python), recommended version 1.8 or above (tested with 1.8.15)
- the QuickCheck library, version 2.x
- the HUnit library (tested with 1.2.x)
- the test-framework libraries, tested versions: `test-framework`: 0.6, `test-framework-hunit`: 0.2.7, `test-framework-quickcheck2`: 0.2.12.1
- `hpc`, which comes with the compiler, so you should already have it
- shelltestrunner, used for running shell-based unit-tests
- temporary library, tested with version 1.1.2.3

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 libghc-hunit-dev \
          libghc-test-framework-dev \
          libghc-test-framework-quickcheck2-dev \
          libghc-test-framework-hunit-dev \
          libghc-temporary-dev \
          hscolour hlint

Or alternatively via `cabal`:

    $ cabal install QuickCheck HUnit \
            test-framework test-framework-quickcheck2 test-framework-hunit \
            temporary 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 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"

Or, more interactively:

    $ ghci
    λ> :set -ddump-splices
    λ> :l src/Ganeti/Objects.hs

And you will get the spliced code as the module is loaded.

To build profiling code you must install the `ghc-prof` (or `gch6-prof`) package, and all the relevant libraries with their `-prof` counterparts. If installing libraries through cabal the config file should include `library-profiling: True` or the `-p` flag should be used. Any library already installed can be updated by passing `--reinstall` as well.

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

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

The binary files generated by compilation and the profiling/coverage files can “break” tab-completion in the sources; they can be ignored, for example, in bash via `.bashrc`:

    FIGNORE='.o:.hi:.prof_o:.tix'

or in emacs via `completion-ignored-extensions` (run `M-x customize-var completion-ignored-extensions`).

### Running individual tests

When developing code, running the entire test suite can be slow. Running individual tests is possible easily for unit-tests, less so for shell-tests (but these are faster, so it shouldn’t be needed).

For Python tests:

    $ export PYTHONPATH=$PWD
    $ python ./test/py/ganeti.mytest

For Haskell tests:

    $ make test/hs/htest && ./test/hs/htest -t pattern

Where `pattern` can be a simple test pattern (e.g. `comma`, matching any test whose name contains `comma`), a test pattern denoting a group (ending with a slash, e.g. `Utils/`), or more complex glob pattern. For more details, see the documentation (on the test-framework homepage).

# Packaging notes

Ganeti is mostly developed and tested on Debian-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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