trapper-project /

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initial migrations issue fixed + other minor changes
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Welcome to the Trapper 1.0 beta repository!


Trapper is an open source, django based web application to manage camera trapping projects. Motion-triggered camera trapping is increasingly becoming an important tool in ecological research. Because of the nature of collected data (multimedia files) even relatively small camera-trapping projects can generate large and complex datasets. The organization of these large collections of multimedia files and efficient querying for a particular subsets of data, especially in a spatio-temporal context, is often a challenging task. Without an appropriate software solution this can become a serious data management problem, leading to delays and inaccessibility of data in the long run. We propose a new approach which, in contrary to available software solutions, is a fully open-source web application using spatially enabled data that can handle arbitrary media types (both pictures and videos), supports collaborative work on a project and data sharing between system users. We used state of the art and well-recognized open-source software components and modern, general purpose programming language Python to design a flexible software framework for data management in camera trapping studies.


The full documentation is in progress...


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Deployment notes

Deployment assumptions

  • system user that is used to run the django application: web
  • home directory: /home/web/trapper
  • nginx setup: server name; this should be changed
  • nginx setup: ssl keys are already generated

System info

We recommend a distribution based on Debian e.g. Ubuntu Server. You have to setup a proper locale:

locale-gen en_US.UTF-8

System level dependencies

apt-get install postgresql-9.5 postgresql-contrib-9.5 postgresql-9.5-postgis
postgresql-server-dev-9.5 python-virtualenv python-dev libxml2-dev libjpeg8-dev
libxslt1-dev libgeos-dev libproj-dev libgdal-dev nginx supervisor rabbitmq-server
ffmpeg libspatialindex-dev libyaml-dev gettext memcached


There is no ffmpeg for trusty (but there is for precise and xenial), so a ppa must be added: sudo add-apt-repository ppa:mc3man/trusty-media

PostGIS manual installation (if needed)

The compilation of PostgGIS requires the root privileges

tar zxvf postgis-2.1.5.tar.gz
cd postgis*
make install

Database configuration

su postgres

# use the same password as in your "" file
# by default it is "trapper"

createuser trapper -R -d -S -E -P

psql -d template1 -c 'create extension postgis;'
psql -d template1 -c 'create extension hstore;'

Django setup

Run the following scripts as the web user:


Then you should configure the email backend. This can be done by modifying the following settings:



These settings should not be changed in the file because it can be accidentally pushed to the repository. Use the instead (this file is excluded from git).


If local SMTP server is used it has to be configured to be able to send email messages. Configuration of the SMTP server is out of the scope of this documentation.

When a new user or new research project is created, emails are sent to all admins defined in a standard django settings file: settings.ADMINS.


It is preffered to define admin list in to protect emails from being publicly available in the repository.

Nginx setup

The following steps require the root privileges.

Update your /etc/nginx/nginx.conf using a template config file conf/nginx.conf.

Copy or symlink conf/trapper.nginx.conf to the nginx config directory (by default it is /etc/nginx/sites-available), then symlink the copied file to /etc/nginx/sites-enabled.

Default trapper configuration assumes that you have already generated SSL certificates. For example you can get free SSL certificates from Let's Encrypt.

Restart the nginx server:

/etc/init.d/nginx restart

If you are using a default configuration then you can edit /etc/hosts and add entry:

and then test your website deployment locally:


You should not use in your production unless you are the owner of this domain. Likely the browser will inform you about the wrong SSL certificate.


The following steps require the root privileges.

Copy or symlink conf/supervisor.conf to /etc/supervisor/conf.d and restart the supervisor:

/etc/init.d/supervisor restart

If everything is setup correctly then supervisorctl output should look like this:

# supervisorctl
trapper                          RUNNING    pid 30969, uptime 0:01:26
trapper-celery-beat              RUNNING    pid 30970, uptime 0:01:26
trapper-celery-cam               RUNNING    pid 30968, uptime 0:01:26
trapper-celery-worker            RUNNING    pid 30971, uptime 0:01:26

External services

There are few external services used by Trapper that are either required or preferred simply to make your work with the application more convenient and more productive.

Email service

The email service is the only one that is required. An access to the SMTP server is required to make the notification framework working correctly.

Deployment notes section provides the example of configuration of the email service.


The SMTP server configuration is not documented here. The trapper administrators are free to use the most suitable solution.


Celery is an external service used for running asynchronous tasks at the server. It is a task queue with focus on real-time processing, while also supporting task scheduling.

The following settings can be used to configure celery's behaviour in the trapper application:

  • CELERY_DATA_ROOT - base directory where celery stores processed files
  • CELERY_ENABLED - if set to False then all tasks will be launched synchronously (default is True)

Thumbnails generation

Each resource can have a thumbnail assigned. The process of thumbnails generation (for images and video files) can be very time consuming. That is why this process is by default moved to a separate asynchronous task and done by celery.

The thumbnail generation process can be tuned with these settings:

  • CELERY_MIN_IMAGE_SIZE - minimal image size in Bytes above which celery will be used (if enabled). Default is 10MB
  • DEFAULT_THUMBNAIL_SIZE - thumbnail image dimensions. By default it's 96x96 px
  • VIDEO_THUMBNAIL_ENABLED if set to False then thumbnails for videos will not be generated


Generating thumbnails for images uses Pillow.


Generating thumbnails for videos uses ffmpeg which has to be installed on the server.

Uploading collections of resources

Users can directly upload collections of resources using provided web interface or in a case of more heavy data sets using alternative methods (see the next section). To facilitate multimedia processing prior to upload there are two python scripts available at :

  • - batch conversion of video files into web-friendly media formats; at the moment only .mp4 and .webm formats are supported; this script uses ffmpeg to convert videos
  • - generates a data package (zipped multimedia files) with accompanying YAML based package definition file which can be further parsed by the trapper backend

Collections of resources that users want to process can be very large and processing them can be very time consuming. Thus, a whole process is delegated to the celery which will process them asynchronously.

The processing of uploaded collections has no custom settings to control the celery behaviour. Tasks are always delegated to the celery unless the celery is disabled with CELERY_ENABLED set to False.

Alternative upload methods

Trapper users have dedicated directories that are created automatically when users accounts are activated. These dedicated directories are associated with users profiles and recognized by the system. Resources or collections of resources can be then uploaded to the storage server using FTP or SSH protocols.


The root user's directory is defined by EXTERNAL_MEDIA_ROOT setting.

(S)FTP example

When the administrator of Trapper wants to enable an alternative upload through (S)FTP for the user alice, he needs to configure the alice (S)FTP account on the server and point it's home directory to EXTERNAL_MEDIA_ROOT/alice/. He has to take care about all necessary permissions that have to be set to allow the user to read and write files within its home directory.


The configuration of the (S)FTP (or SSH) server is out of the scope of this documentation.

Software components


The following is the list of the most important software components that have been used to design and implement Trapper:

  • Ubuntu

    A base operating system under which Trapper was developed and tested.

  • PostgreSQL

    The open source and industry standard relational database management system (RDBMS) with PostGIS as its spatial extension.

  • nginx

    nginx [engine x] is an HTTP and reverse proxy server, a mail proxy server, and a generic TCP proxy server.

  • Gunicorn

    This pure-python application is used to serve Trapper project.

  • Supervisor

    This application is used to control all project related external applications like celery.

  • Celery

    This python application is used to run various tasks in asnynchronous mode allowing Trapper to work faster and more efficient. The celery is used to generate thumbnails from large files or videos, or to process uploaded collections by users.

  • Django

    The core component of Trapper, a high-level Python web framework maintained by the Django Software Foundation. Django framework simplifies and significantly speeds up the creation of complex, database-driven websites and emphasizes reusability and pluggability of their components. Additionally, the following 3rd party, open source django applications have been used to develop Trapper. For a complete list of these applications see this file

  • uMAP uMap lets you create maps with OpenStreetMap layers in a minute and embed them in your site. It uses django-leaflet-storage and Leaflet.Storage, built on top of Django and Leaflet.


Trapper's front-end is developed based on three independent solutions:

  1. HTML (version 5) templates and their CSS styles (powered by SASS)
  2. set of scripts written in pure JavaScript (ECMAscript 5).
  3. all the external libraries and frameworks included in the project:
  • Twitter Bootstrap

    Bootstrap Sass Official which is official SASS version of Twitter Bootstrap. This library provides a set of HTML components and CSS styles used for Trapper scaffold creation.

  • Font Awesome

    Font Awesome - webfont of vector icons used in the project.

  • Angular JS

    Angular JS all the grids/tables including their filters has been build on top of this Google's framework

  • Angular Cookies

    Official angular module for cookies management.

  • Angular Sanitize

    Official angular module which improves angular templates data binding.

  • Moment

    Extremaly powerful library for date parsing & manipulation.

  • Select2

    Complete solution that extends default HTML select controls.

  • Select2 Bootstrap CSS

    CSS styles for Select2 so it fits Twitter Bootstrap feel & look.

  • Bootstrap WYSIHTML5

    Javascript Plugin which brings WYSIWYG text editor to the table.

  • Bootstrap Datepicker

    Javascript Widget - simple datepicker.

  • Jquery Timepicker

    Jquery Widget which is just a timepicker.

  • Bootstrap Datetimepicker

    Javascript Widget that combines both time and date picker.

  • Video JS

    This library extends standard HTML5 video players.

  • Video JS Rangeslider

    Video JS plugin that allows to set and get video sequences.


X-Sendfile (see for example allows verification of django-based user's permissions before specific content is sent to a user (e.g. multimedia file). However, Django will not serve a content - it is done by a web server that can handle it much more efficient.


Basic X-Sendfile flow:

  1. a request from nginx is sent to the Trapper application
  2. Django determines if a user has right permissions to see a content
  • if access is granted special headers will be included in a response to inform nginx how to proceed
  • if access is not granted negative (forbidding) response is returned
  1. a response is received back by nginx
  2. a proper content is sent to a user by nginx


# Base place for media that should be served through x-sendfile

# Default directory within SENDFILE_ROOT for files served through x-sendfile

# Used by a middleware to fake x-sendfile for development instances

# Header that will be added to a response. Differs between web servers.
# This one is for nginx
SENDFILE_HEADER = 'X-Accel-Redirect'


All resources (part of the storage application) use X-Sendfile to control the access to the file, file_thumbnail, file_preview and extra_file model fields.

Trapper does not use direct urls to serve images/movies/audio. All media files are stored in SENDFILE_ROOT + SENDFILE_MEDIA_PREFIX and each handled field has its own method responsible for returning a proper url. Instead of returning a direct url to a media file, a special serve-view url is returned.

In this view a requested media file of given resource is verified against currently logged in user's permissions. If a user can view details of this resource, then a media file can be served by nginx and django will add special headers to a response. Otherwise a default image (access forbidden) is returned.


The nginx configuration is quite minimalistic:

location /media/protected/ {
     alias /home/web/trapper/trapper/media/protected/;

Using the internal flag allows files from a specified location to be served only by nginx.

Django admin

Since nginx will not serve media files directly, django admin panel had to be altered to allow using fileinput widget (which shows url to actual media url if given field is not empty).

Widget combined with a special view allows user to see a media file from protected directory directly but only if request is made by user that is staff or is superuser. Otherwise the forbidden response is returned.

An example of a url for a direct media file access looks like: