Installation

This guide will help you to install pretalx on Linux. This setup is suitable to support events in usual sizes, but the guide does not go into performance tuning or customisation options beyond the standard settings.

Warning

While we try to make it straightforward to run pretalx, it still requires some Linux experience to get it right, particularly to make sure that standard security practices are followed. If you’re not feeling comfortable managing a Linux server, check out our hosting and service offers at pretalx.com.

For the more automation-savvy, we also provide an Ansible role that follows this guide. If you prefer a docker setup, there is a docker-compose setup. Please note that the docker setup is community provided and not officially supported.

Step 0: Prerequisites

Please set up the following systems beforehand. We can’t go into their use and configuration here, but please have a look at the linked pages.

  • Python 3.7 or newer and a pip to match. You can use python -V and pip3 -V to check.

  • An SMTP server to send out mails

  • An HTTP reverse proxy, e.g. nginx or Apache to allow HTTPS connections

  • A database server: MySQL 5.7+ or MariaDB 10.2+ or PostgreSQL 10+. You can use SQLite, but we strongly recommend not to run SQLite in production. Given the choice, we’d recommend to use PostgreSQL.

  • A redis server, if you want to use pretalx with an asynchronous task runner or improved caching.

We assume that you also have the usual security measures in place, such as a firewall. If you’re new to Linux and firewalls, we recommend that you start with ufw.

Please ensure that the environment used to run pretalx is configured to work with non-ASCII file names. You can check this by running:

python -c "import sys; print(sys.getfilesystemencoding())"

This should output "utf-8".

Note

Please do not run pretalx without HTTPS encryption. You’ll handle user data and thanks to Let’s Encrypt, SSL certificates are free these days. We also do not provide support for HTTP-exclusive installations except for evaluation purposes.

Step 1: Unix user

Hint

All code lines prepended with a # symbol are commands that you need to execute on your server as root user (e.g. using sudo); you should run all lines prepended with a $ symbol as the unprivileged user.

As we do not want to run pretalx as root, we first create a new unprivileged user:

# adduser pretalx --disabled-password --home /var/pretalx

Step 2: Database setup

Having the database server installed, we still need a database and a database user. We recommend using PostgreSQL. pretalx also works (and runs tests against) MariaDB and SQLite. If you do not use PostgreSQL, please refer to the appropriate documentation on how to set up a database. For PostgreSQL, run these commands:

# sudo -u postgres createuser pretalx -P
# sudo -u postgres createdb -O pretalx pretalx

Make sure that your database encoding is UTF-8. You can check with this command:

# sudo -u postgres psql -c 'SHOW SERVER_ENCODING'

When using MySQL, make sure you set the character set of the database to utf8mb4, e.g. like this:

mysql > CREATE DATABASE pretalx DEFAULT CHARACTER SET utf8mb4 DEFAULT COLLATE utf8mb4_unicode_ci

Step 3: Package dependencies

Besides the packages above, you might need local system packages to build and run pretalx. We cannot maintain an up-to-date dependency list for all Linux flavours, but we can offer you a list for Ubuntu. You should be able to find the appropriate packages on your system from there:

On Ubuntu-like systems, you will need packages like:

  • build-essential

  • libssl-dev

  • python3-dev

  • gettext

  • libmysqlclient-dev if you use MariaDB

pretalx requires Python 3.6+. If you cannot find one of these versions for your system, you can build it from source.

Note

You may need to replace all following mentions of pip with pip3.

Step 4: Configuration

Now we’ll create a configuration directory and configuration file for pretalx:

# mkdir /etc/pretalx
# touch /etc/pretalx/pretalx.cfg
# chown -R pretalx:pretalx /etc/pretalx/
# chmod 0600 /etc/pretalx/pretalx.cfg

Fill the configuration file /etc/pretalx/pretalx.cfg with the following content. But don’t forget to adjust it to your environment!

# This is an example pretalx configuration file.
# Documentation: https://docs.pretalx.org/administrator/configure.html

[filesystem]
data = /var/pretalx/data
static = /var/pretalx/static

[site]
debug = False
url = https://pretalx.mydomain.com

[database]
# For MySQL, replace with "mysql"
backend = postgresql
name = pretalx
user = pretalx
# For MySQL, enter the user password. For PostgreSQL on the same host,
# we don't need one because we can use peer authentification if our
# PostgreSQL user matches our unix user.
password = Change this in production or you're going to have a bad time
# For MySQL, you can use a local socket, e.g. /var/run/mysqld/mysqld.sock
# For a remote host, supply an IP address
# For local postgres authentication, you can leave the host empty
host = localhost
port = 5432

[mail]
from = admin@localhost
host = localhost
port = 25
user = admin
password = Change this in production or you're going to have a bad time
tls = False
ssl = True

Check out Configuration for details on the available configuration options. There are more options available than we’re showing you here!

Step 5: Installation

Please execute the following steps as the pretalx user. This isolates the pretalx environment from your global Python versions and binaries:

$ pip install --user -U pip setuptools wheel gunicorn

pretalx works with your choice of database backends – we recommend using PostgreSQL, but MySQL and SQLite work as well. Use this command to install the database driver (unless you use SQLite, which has its driver built in):

Database

pip package

PostgreSQL

pip install --user -U psycopg2-binary

MySQL / MariaDB

pip install --user -U mysqlclient

Now we will install pretalx itself:

$ pip install --user --upgrade-strategy eager -U pretalx

If you intend to run pretalx with asynchronous task runners or with redis as cache server, you can install pretalx[redis] instead, which will pull in the appropriate dependencies. Please note that you should also use pretalx[redis] when you upgrade pretalx in this case.

We also need to create a data directory:

$ mkdir -p /var/pretalx/data/media

We compile static files and translation data and create the database structure:

$ python -m pretalx migrate
$ python -m pretalx rebuild

Now, create a user with administrator rights, an organiser and a team by running:

$ python -m pretalx init

Step 6: Starting pretalx as a service

We recommend starting pretalx using systemd to make sure it starts up after a reboot. Create a file named /etc/systemd/system/pretalx-web.service with the following content:

[Unit]
Description=pretalx web service
After=network.target

[Service]
User=pretalx
Group=pretalx
WorkingDirectory=/var/pretalx/.local/lib/python3.8/site-packages/pretalx
ExecStart=/var/pretalx/.local/bin/gunicorn pretalx.wsgi \
                      --name pretalx --workers 4 \
                      --max-requests 1200  --max-requests-jitter 50 \
                      --log-level=info --bind=127.0.0.1:8345
Restart=on-failure

[Install]
WantedBy=multi-user.target

If you decide to use Celery (giving you asynchronous execution for long-running tasks), you’ll also need a second service /etc/systemd/system/pretalx-worker.service with the following content:

[Unit]
Description=pretalx background worker
After=network.target

[Service]
User=pretalx
Group=pretalx
WorkingDirectory=/var/pretalx/.local/lib/python3.8/site-packages/pretalx
ExecStart=/var/pretalx/.local/bin/celery -A pretalx.celery_app worker -l info
WorkingDirectory=/var/pretalx
Restart=on-failure

[Install]
WantedBy=multi-user.target

You can now run the following commands to enable and start the services:

# systemctl daemon-reload
# systemctl enable pretalx-web pretalx-worker
# systemctl start pretalx-web pretalx-worker

Step 7: SSL

The following snippet is an example on how to configure an nginx proxy for pretalx:

server {
    listen 80 default_server;
    listen [::]:80 ipv6only=on default_server;
    server_name pretalx.mydomain.com;
}
server {
    listen 443 default_server;
    listen [::]:443 ipv6only=on default_server;
    server_name pretalx.mydomain.com;

    ssl on;
    ssl_certificate /path/to/cert.chain.pem;
    ssl_certificate_key /path/to/key.pem;

    gzip off;
    add_header Referrer-Policy same-origin;
    add_header X-Content-Type-Options nosniff;

    location / {
        proxy_pass http://localhost:8345/;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto https;
        proxy_set_header Host $http_host;
    }

    location /media/ {
        gzip on;
        alias /var/pretalx/data/media/;
        add_header Content-Disposition 'attachment; filename="$1"';
        expires 7d;
        access_log off;
    }

    location /static/ {
        gzip on;
        alias /path/to/static.dist/;
        access_log off;
        expires 365d;
        add_header Cache-Control "public";
    }
}

We recommend reading about setting strong encryption settings for your web server.

Step 8: Check the installation

You can make sure the web interface is up and look for any issues with:

# journalctl -u pretalx-web

If you use Celery, you can do the same for the worker processes (for example in case the emails are not sent):

# journalctl -u pretalx-worker

If you’re looking for errors, check the pretalx log. You can find the logging directory in the start-up output.

Once pretalx is up and running, you can also find up to date administrator information at https://pretalx.yourdomain.com/orga/admin/.

Step 9: Provide periodic tasks

There are a couple of things in pretalx that should be run periodically. It doesn’t matter how you run them, so you can go with your choice of periodic tasks, be they systemd timers, cron, or something else entirely.

In the same environment as you ran the previous pretalx commands (e.g. the pretalx user), you should run

  • python -m pretalx runperiodic somewhere every five minutes and once per hour.

  • python -m pretalx clearsessions about once a month.

You could for example configure the pretalx user cron like this:

15,45 * * * * python -m pretalx runperiodic

Next Steps

You made it! You should now be able to reach pretalx at https://pretalx.yourdomain.com/orga/ Log in as the administrator you configured above, and create your first event!

Check out Configuration for details on the available configuration options.

If you want to read about updates, backups, and monitoring, head over to our Maintenance documentation!