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## Introduction

Comprehensive Knowledge Archive Network (CKAN) Software.

See :mod:ckan.__long_description__ for more information.

## Developer Installation

These are instructions to get developing with CKAN. Instructions for deploying CKAN to a server are at: :doc:deployment (doc/deployment.rst).

Before you start it may be worth checking CKAN has passed the auto build and tests. See: http://buildbot.okfn.org/waterfall

1. Ensure these packages are installed:

Package

Description

mercurial

Source control

python-dev

Python interpreter v2.5 - v2.7 and dev headers

postgresql

PostgreSQL database

libpq-dev

PostgreSQL library

libxml2-dev

XML library development files

libxslt-dev

XSLT library development files

python-virtualenv

Python virtual environments

wget

build-essential

Tools for building source code

For ubuntu you can install these like so:

sudo apt-get install build-essential libxml2-dev libxslt-dev
sudo apt-get install wget mercurial postgresql libpq-dev
sudo apt-get install python-dev python-psycopg2 python-virtualenv

2. Create a python virtual environment

In your home directory run the command below. It is currently important to call your virtual environment pyenv so that the automated deployment tools work correctly.

cd ~
virtualenv pyenv


Tip

If you don't have a python-virtualenv package in your distribution you can get a virtualenv.py script from within the virtualenv source distribution and then run python virtualenv.py pyenv instead.

To help with automatically installing CKAN dependencies we use a tool called pip. Make sure you have activated your environment (see step 3) and then install it from an activated shell like this:

easy_install pip


To work with CKAN it is best to adjust your shell settings so that your shell uses the virtual environment you just created. You can do this like so:

. pyenv/bin/activate


When your shell is activated you will see the prompt change to something like this:

(pyenv)[ckan@host ~/]\$


An activated shell looks in your virtual environment first when choosing which commands to run. If you enter python now it will actually run ~/pyenv/bin/python which is what you want.

4. Install CKAN code and required Python packages into the new environment

pip install --ignore-installed -e hg+http://bitbucket.org/okfn/ckan#egg=ckan


CKAN has a set of dependencies it requires which you should install too:

pip install --ignore-installed -r pyenv/src/ckan/requires/lucid_missing.txt -r pyenv/src/ckan/requires/lucid_conflict.txt


The --ignore-installed option ensures pip installs software into this virtual environment even if it is already present on the system.

If you are using Ubuntu Lucid you can install the rest of the dependencies from the system versions like this:

sudo apt-get install python-psycopg2 python-lxml python-sphinx
sudo apt-get install python-pylons python-formalchemy python-repoze.who
sudo apt-get install python-repoze.who-plugins python-tempita python-zope.interface


If you are not using Ubuntu Lucid you'll still need to install all the dependencies that would have been met in the apt-get install command at the start. You can do so like this:

pip install --ignore-installed -r pyenv/src/ckan/requires/lucid_present.txt


This will take a long time. Particularly the install of the lxml package.

At this point you will need to deactivate and then re-activate your virtual environment to ensure that all the scripts point to the correct locations:

deactivate
. pyenv/bin/activate

5. Setup a PostgreSQL database

List existing databases:

psql -l


It is advisable to ensure that the encoding of databases is 'UTF8', or internationalisation may be a problem. Since changing the encoding of PostgreSQL may mean deleting existing databases, it is suggested that this is fixed before continuing with the CKAN install.

Next you'll need to create a database user if one doesn't already exist.

Tip

If you choose a database name, user or password which are different from those suggested below then you'll need to update the configuration file you'll create in the next step.

Here we choose ckantest as the database and ckanuser as the user:

sudo -u postgres createuser -S -D -R -P ckantest


It should prompt you for a new password for the CKAN data in the database. It is suggested you enter pass for the password.

Now create the database, which we'll call ckantest (the last argument):

sudo -u postgres createdb -O ckantest ckantest

1. Create a CKAN config file

Make sure you are in an activated environment (see step 3) so that Python Paste and other modules are put on the python path (your command prompt will start with (pyenv) if you have) then change into the ckan directory which will have been created when you installed CKAN in step 4 and create the config file development.ini using Paste:

cd pyenv/src/ckan
paster make-config ckan development.ini


You can give your config file a different name but the tests will expect you to have used development.ini so it is strongly recommended you use this name, at least to start with.

If you used a different database name or password when creating the database in step 5 you'll need to now edit development.ini and change the sqlalchemy.url line, filling in the database name, user and password you used.

sqlalchemy.url = postgresql://ckantest:pass@localhost/ckantest


Other configuration, such as setting the language of the site or editing the visual theme are described in :doc:configuration (doc/configuration.rst)

Caution!

Advanced users: If you are using CKAN's fab file capability you currently need to create your config file as pyenv/ckan.net.ini so you will probably have ignored the advice about creating a development.ini file in the pyenv/src/ckan directory. This is fine but CKAN probably won't be able to find your who.ini file. To fix this edit pyenv/ckan.net.ini, search for the line who.config_file = %(here)s/who.ini and change it to who.config_file = who.ini.

We are moving to a new deployment system where this incompatibility will be fixed.

1. Create database tables

Now that you have a configuration file that has the correct settings for your database, you'll need to create the tables. Make sure you are still in an activated environment with (pyenv) at the front of the command prompt and then from the pyenv/src/ckan directory run this command:

paster db init


You should see Initialising DB: SUCCESS. If you are not in the pyenv/src/ckan directory or you don't have an activated shell, the command will not work.

If the command prompts for a password it is likely you haven't set up the database configuration correctly in step 6.

1. Create the cache directory

You need to create the Pylon's cache directory specified by 'cache_dir' in the config file.

(from the pyenv/src/ckan directory):

mkdir data

1. Run the CKAN webserver

NB If you've started a new shell, you'll have to activate the environment again first - see step 3.

(from the pyenv/src/ckan directory):

paster serve development.ini


The CKAN homepage should load without problem.

## Test

### Setting up to test

Make sure you've created a config file: pyenv/ckan/development.ini

Ensure you have activated the environment:

. pyenv/bin/activate


pip install --ignore-installed nose


At this point you will need to deactivate and then re-activate your virtual environment to ensure that all the scripts point to the correct locations:

deactivate
. pyenv/bin/activate


### Running developer tests

Here's how you start the quick development tests:

cd pyenv/src/ckan
nosetests ckan/tests --ckan


You must run the tests from the CKAN directory as shown above, otherwise the --ckan plugin won't work correctly.

Caution!

By default, the test run is 'quick and dirty' - only good enough as a check before committing code. See the next section for improved ways of running tests.

### Test configurations

The default way to run tests is defined in test.ini (which is the default config file for nose - change it with option "--with-pylons"). This specifies to use Sqlite and sets faster_db_test_hacks, which are compromises.

cd pyenv/src/ckan
nosetests ckan/tests --ckan

Although Sqlite is useful for testing a large proportion of CKAN, actually in deployment, CKAN must run with PostgreSQL. Running the tests against PosgreSQL is slower but more thorough for two reasons:
1. You test subtleties of PostgreSQL
2. CKAN's default search relies on PostgreSQL's custom Full Text Search, so these (100 or so) tests are skipped when running against Sqlite.

So when making changes to anything involved with search or closely related to the database, it is wise to test against PostgreSQL.

To test against PosgreSQL:
1. Edit your local development.ini to specify a PostgreSQL database with the sqlalchemy.url parameter.
2. Tell nose to use test-core.ini (which imports settings from development.ini)
nosetests ckan/tests --ckan --with-pylons=test-core.ini


The test suite takes a long time to run against standard PostgreSQL (approx. 15 minutes, or close to an hour on Ubuntu/10.04 Lucid).

This can be improved to between 5 and 15 minutes by running PostgreSQL in memory and turning off durability, as described at <http://www.postgresql.org/docs/9.0/static/non-durability.html>.

If your changes require a model change, you'll need to write a migration script. To ensure this is tested as well, you should instead run the tests this way:

nosetests ckan/tests --ckan --ckan-migrate --with-pylons=test-core.ini


By default, tests are run using the model defined in ckan/model, but by using the --ckan-migrate option the tests will run using a database that has been created using the migration scripts, which is the way the database is created and upgraded in production. These tests are the most thorough and will take around 20 minutes.

Caution!

Ordinarily, you should set development.ini to specify a PostgreSQL database so these also get used when running test-core.ini, since test-core.ini inherits from development.ini. If you were to change the sqlalchemy.url option in your development.ini file to use SQLite, the command above would actually test SQLite rather than PostgreSQL so always check the setting in development.ini to ensure you are running the full tests.

Note

A common error when wanting to run tests against a particular database is to change the sqlalchemy.url in test.ini or test-core.ini. The problem is that these are versioned files and people have checked in these by mistake, creating problems for all other developers and the buildbot. This is easily avoided by only changing the sqlalchemy.url in your local development.ini and testing --with-pylons=test-core.ini.

### Testing extensions

CKAN extensions ordinarily have their own test.ini that refers to the ckan test.ini, so you can run them in exactly the same way. For example:

cd ckanext-dgu
nosetests ckanext/dgu/tests --ckan
nosetests ckanext/dgu/tests --ckan --with-pylons=test-core.ini


## Development

CKAN is an open source project and contributions are welcome!

There are a number of stakeholders in the direction of the project, so we discuss large changes and new features on the ckan-discuss list: http://lists.okfn.org/mailman/listinfo/ckan-discuss

New developers should aquaint themselves with the documentation (see below). Proposed changes should be made on a personal CKAN fork (on BitBucket for example). Request merging with the mainline via the ckan-discuss list.

We have policies for check-ins that ensure the build doesn't break etc. on http://ckan.org/#ProjectProcessesandPolicies which should be followed unless someone builds concensus to change it.

## Documentation

This README file is part of the Developer Documentation, viewable at: http://packages.python.org/ckan/ and stored in the CKAN repo at ckan/doc.

The Developer Docs are built using Sphinx:

python setup.py build_sphinx

(The docs are also uploaded via dav to http://knowledgeforge.net/ckan/doc/ckan/for backwards compatability).

## Contributors

• Rufus Pollock <rufus [at] rufuspollock [dot] org>