ogn-python

A database backend for the Open Glider Network. The ogn-python module saves all received beacons into a database with SQLAlchemy. It connects to the OGN aprs servers with python-ogn-client. It requires redis, PostgreSQL, PostGIS and TimescaleDB.

Examples

Installation and Setup

1. Checkout the repository

   git clone https://github.com/glidernet/ogn-python.git
   cd ogn-python
   

2. Optional: Create and use a virtual environment

   python3 -m venv my_environment
   source my_environment/bin/activate
   

3. Install python requirements

   pip install -r requirements.txt
   

4. Install PostgreSQL with PostGIS and TimescaleDB Extension. Create a database (use "ogn" as default, otherwise you have to modify the configuration, see below)

5. Install redis for asynchronous tasks (like database feeding, takeoff/landing-detection, ...)

   apt-get install redis-server
   

6. Set the environment Your environment variables must point to the configuration file and to the app path.

   export OGN_CONFIG_MODULE="config.py"
   export FLASK_APP=ogn_python.py
   

7. Create database

   flask database init
   

8. Optional: Import world border dataset (needed if you want to know the country a receiver belongs to, etc.) Get the World Borders Dataset and unpack it. Then import it into your database (we use "ogn" as database name).

   shp2pgsql -s 4326 TM_WORLD_BORDERS-0.3.shp world_borders_temp | psql -d ogn
   psql -d ogn -c "INSERT INTO countries SELECT * FROM world_borders_temp;"
   psql -d ogn -c "DROP TABLE world_borders_temp;"
   

9. Get world elevation data (needed for AGL calculation) Sources: There are many sources for DEM data. It is important that the spatial reference system (SRID) is the same as the database which is 4326. The GMTED2010 Viewer provides data for the world with SRID 4326. Just download the data you need.

10. Import the GeoTIFF into the elevation table:

    raster2pgsql *.tif -s 4326 -d -M -C -I -F -t 25x25 public.elevation | psql -d ogn
    

11. Import Airports (needed for takeoff and landing calculation). A cup file is provided under tests:

    flask database import_airports tests/SeeYou.cup 
    

12. Import DDB (needed for registration signs in the logbook).

    flask database import_ddb
    

13. Optional: Use supervisord You can use Supervisor to control the complete system. In the directory deployment/supervisor we have some configuration files to feed the database (ogn-feed), run the celery worker (celeryd), the celery beat (celerybeatd), the celery monitor (flower), and the python wsgi server (gunicorn). All files assume that we use a virtual environment in "/home/pi/ogn-python/venv". Please edit if necessary.

There is also a Vagrant environment for the development of ogn-python. You can create and start this virtual machine with vagrant up and login with vagrant ssh. The code of ogn-python will be available in the shared folder /vagrant.

Usage

Running the aprs client and task server

To schedule tasks like takeoff/landing-detection (logbook.compute), Celery with Redis is used. The following scripts run in the foreground and should be deamonized (eg. use supervisord).

• Start the aprs client

  flask gateway run
  

• Start a task server (make sure redis is up and running)

  celery -A celery_app worker -l info
  

• Start the task scheduler (make sure a task server is up and running)

  celery -A celery_app beat -l info
  

Flask - Command Line Interface

Usage: flask [OPTIONS] COMMAND [ARGS]...

  A general utility script for Flask applications.

  Provides commands from Flask, extensions, and the application. Loads the
  application defined in the FLASK_APP environment variable, or from a
  wsgi.py file. Setting the FLASK_ENV environment variable to 'development'
  will enable debug mode.

    $ export FLASK_APP=app.py
    $ export FLASK_ENV=development
    $ flask run

Options:
  --version  Show the flask version
  --help     Show this message and exit.

Commands:
  database  Database creation and handling.
  db        Perform database migrations.
  export    Export data in several file formats.
  flights   Create 2D flight paths from data.
  gateway   Connection to APRS servers.
  logbook   Handling of takeoff/landings and logbook data.
  routes    Show the routes for the app.
  run       Run a development server.
  shell     Run a shell in the app context.

Most commands are command groups, so if you execute this command you will get further (sub)commands.

Available tasks

• app.tasks.transfer_to_database - Take sender and receiver messages from redis and put them into the db.
• app.tasks.update_takeoff_landings - Compute takeoffs and landings.
• app.tasks.update_logbook - Add/update logbook entries.
• app.tasks.update_logbook_max_altitude - Add max altitudes in logbook when flight is complete (takeoff and landing).
• app.tasks.update_statistics - Calculate several statistics (also the sender/receiver rankings).
• app.tasks.import_ddb - Import registered devices from the DDB.

If the task server is up and running, tasks could be started manually. Here we compute takeoffs and landings for the past 90 minutes:

python3
>>>from app.tasks import update_takeoff_landings
>>>update_takeoff_landings.delay(last_minutes=90)

or directly from command line:

celery -A celery_app call import_ddb

Notes for Raspberry Pi

For matplotlib we need several apt packages installed:

apt install libatlas3-base libopenjp2-7 libtiff5

License

Licensed under the AGPLv3.