Installing PyBossa

PyBossa is a python web application built using the Flask micro-framework.

Pre-requisites:

  • Python >= 2.7.2, <3.0
  • PostgreSQL version 9.1 and the Python bindings for PostgreSQL database.
  • Redis >= 2.6
  • pip for installing python packages (e.g. on ubuntu python-pip)

Note

We recommend to install PyBossa using a virtualenv as it will create a an isolated Python environment, helping you to manage different dependencies and versions without having to deal with root permissions in your server machine.

virtualenv creates an environment that has its own installation directories, that doesn’t share libraries with other virtualenv environments (and optionally doesn’t access the globally installed libraries either).

You can install the software if you want at the system level if you have root privileges, however this may lead to broken dependencies in the OS for all your Python packages, so if possible, avoid this solution and use the virtualenv solution.

Setting things up

Before proceeding to install PyBossa you will need to configure some other applications and libraries in your system. In this page, you will get a step by step guide about how to install all the required packages and libraries for PyBossa using the latest Ubuntu Server Long Term Support version available at the moment.

Installing git -a distributed version control system

PyBossa uses the git distributed version control system for handling the PyBossa server source code as well as the template projects.

Git is a freen and open source distributed version control system designed to handle everything from small to very large projects with seepd and efficiency.

In order to install the software, all you have to do is:

sudo apt-get install git

Installing the PostgreSQL database

PostgreSQL is a powerful, open source object-relational database system. It has more than 15 years of active development and a proven architecture that has earned it a strong reputation for reliability, data integrity, and correctness.

PyBossa uses PostgreSQL as the main database for storing all the data, and you the required steps for installing it are the following:

sudo apt-get install postgresql-9.1

Installing the PyBossa Python requirements

Installing the required libraries for PyBossa is a step that will need to use some compilers and dev libraries in order to work. Thus, you will need to install the following packages:

sudo apt-get install postgresql-server-dev-9.1 python-dev swig libjpeg-dev

Then, you are ready to download the code and install the required libraries for running PyBossa.

Note

We recommend you to install the required libraries using a virtual environment with the command virtualenv (you can install the package python-virtualenv). This will allow to have all the libraries for PyBossa in one folder of your choice, so cleaning the installation would be as simple as deleting that folder without affecting your system.

If you decide to use a virtualenv then, follow these steps (lines starting with # are comments):

# get the source code
git clone --recursive https://github.com/PyBossa/pybossa
# Access the source code folder
cd pybossa
virtualenv env
# Activate the virtual environment
source env/bin/activate
# Install the required libraries
pip install -r requirements.txt

Otherwise you should be able to install the libraries in your system like this:

# get the source
git clone --recursive https://github.com/PyBossa/pybossa
# Access the source code folder
cd pybossa
# Install the required libraries
pip install -r requirements.txt

Note

Vim editor is a very popular text editor in GNU/Linux systems, however it may be difficult for some people if you have never used it before. Thus, if you want to try another and much simpler editor for editing the configuration files you can use the GNU Nano editor.

Create a settings file and enter your SQLAlchemy DB URI (you can also override default settings as needed):

cp settings_local.py.tmpl settings_local.py
# now edit ...
vim settings_local.py

Note

Alternatively, if you want your config elsewhere or with different name:

cp settings_local.py.tmpl {/my/config/file/somewhere}
export PYBOSSA_SETTINGS={/my/config/file/somewhere}

Create the alembic config file and set the sqlalchemy.url to point to your database:

cp alembic.ini.template alembic.ini
# now set the sqlalchemy.url ...

Installing Redis

Since version v0.2.1, PyBossa uses Redis not only for caching objects and speed up the site, but also for limiting the usage of the API requests.

Redis can be installed via your GNU/Linux distribution package system (check that it is at least version 2.6) or downloading the package directly from its official Redis site.

Once you have downloaded it, and installed it, you will need to run two instances:

  • Redis-server: as a master node, accepting read and write operations.
  • Redis-sentinel: as a sentinel node, to configure the master and slave Redis nodes.

If you have installed the server via your distribution package system, then, the server will be running already. If this is not the case, check the official documentation of Redis to configure it and run it. The default values should be fine.

Note

Please, make sure that you are running version >= 2.6

Note

If you have installed the software using the source code, then, check the contrib folder, as there is a specific folder for Redis with init.d start scripts. You only have to copy that file to /etc/init.d/ and adapt it to your needs.

Redis can be run in sentinel mode with the –sentinel arg, or by its own command named: redis-sentinel. This will vary from your distribution and version of Redis, so check its help page to know how you can run it.

In any case, you will need to run a sentinel node, as PyBossa uses it to load-balance the queries, and also to autoconfigure the master and slaves automagically.

In order to run PyBossa, you will need first to configure a Sentinel node. Create a config file named sentinel.conf with something like this:

sentinel monitor mymaster 127.0.0.1 6379 2
sentinel down-after-milliseconds mymaster 60000
sentinel failover-timeout mymaster 180000
sentinel parallel-syncs mymaster 1

In the contrib folder you will find a file named sentinel.conf that should be enough to run the sentinel node. Thus, for running it:

redis-server contrib/sentinel.conf --sentinel

Note

Please, make sure that you are running version >= 2.6

Note

If you have installed the software using the source code, then, check the contrib folder, as there is a specific folder for Redis with init.d start scripts. You only have to copy that file to /etc/init.d/ and adapt it to your needs.

Speeding up the site

PyBossa comes with a Cache system that it is enabled by default. PyBossa uses a Redis server to cache some objects like projects, statistics, etc. The system uses the Sentinel feature of Redis, so you can have several master/slave nodes configured with Sentinel, and your PyBossa server will use them “automagically”.

Once you have started your master Redis-server to accept connections, Sentinel will manage it and its slaves. If you add a slave, Sentinel will find it and start using it for load-balancing queries in PyBossa Cache system.

For more details about Redis and Sentinel, please, read the official documentation.

If you want to disable it, you can do it with an environment variable:

export PYBOSSA_REDIS_CACHE_DISABLED='1'

Then start the server, and nothing will be cached.

Note

Important: We highly recommend you to not disable the cache, as it will boost the performance of the server caching SQL queries as well as page views. If you have lots of projects with hundreds of tasks, you should enable it.

Note

Important: Sometimes Redis is a bit outdated in your Linux distribution. If this is the case, you will need to install it by hand, but it is really easy and well documented in the official Redis site.

PyBossa uses the Python libraries RQ and RQScheduler to allow slow or computational-heavy tasks like the refreshment of the cache, to be run in the background in an asynchronous way.

Note

If you think you won’t need this feature, just skip the rest of the section.

To do so, you will need two additional Python processes to run in the background: the worker and the scheduler. The scheduler will create this tasks in a periodic basis so that the worker then executes them when needed.

To run the scheduler, just run the following command in a console:

rqscheduler --host IP-of-your-redis-master-node

Similarly, to get the tasks done by the worker, run:

python app_context_rqworker.py scheduled_jobs

It is also recommended the use of supervisor for running these processes in an easier way and with a single command.

Configuring the DataBase

You need first to add a user to your PostgreSQL DB:

sudo su postgres
createuser -d -P pybossa

Use password tester when prompted.

Note

You should use the same user name that you have used in the settings_local.py and alembic.ini files.

After running the last command, you maybe also have to answer to these questions:

  • Shall the new role be a super user? Answer n (press the n key).
  • Shall the new role be allowed to create databases? Answer y (press the y key).
  • Shall the new role be allowed to create more new roles? Answer n (press the n key).

And now, you can create the database:

createdb pybossa -O pybossa

Finally, exit the postgresql user:

exit

Then, populate the database with its tables:

python cli.py db_create

Run the web server:

python run.py

Open in your web browser the following URL:

http://localhost:5000

And if you see the following home page, then, your installation has been completed:

http://i.imgur.com/hPtgo6S.png

Updating PyBossa

Update PyBossa core and migrating the database table structure

Sometimes, the PyBossa developers add a new column or table to the PyBossa server, forcing you to carry out a migration of the database. PyBossa uses Alembic for performing the migrations, so in case that your production server need to upgrade the DB structure to a new version, all you have to do is to:

git pull origin master
pip install -r requirements.txt
alembic upgrade head

The first command will get you the latest source code. Then new libraries are installed or upgraded. And Alembic is upgrading the database structure.

Note

If you are using the virtualenv be sure to activate it before running the Alembic upgrade command.

Migrating Your Old DB Records

In versions prior to v0.2.3, HTML was supported as the default option for the ‘long_description’ field in apps. In new versions of PyBossa, Markdown has been adopted as the default option. However, you can use HTML instead of Markdown by modifying the default PyBossa theme or using your own forked from the default one.

If you were have been using PyBossa for a while you may have apps in your database whose ‘long_description’ is in HTML format. Hence, if you are using the default theme for PyBossa you will no longer see them rendered as HTML and may have some issues.

In order to avoid this, you can run a simple script to convert all the DB app’s ‘long_description’ field from HTML to Markdown, just by running the following commands:

pip install -r requirements.txt
python cli.py markdown_db_migrate

The first command will install a Python package that will handle the HTML to Markdown conversion, while the second one will convert your DB entries.

Note

As always, if you are using the virtualenv be sure to activate it before running the pip install command.