Aura Engine

Aura Engine is a play-out engine as part of Aura Radio Software Suite, specifically build for the requirements of community radios.

• Aura Engine
  • Features
  • Architecture
  • Installation
  • Configuration
  • Running Engine
    • Development
    • Production
      • API Server
  • Logging
  • About
  • Resources

Features

• Play audio from multiple sources
• Dynamic switching of sources
• Record output to filesystem
• Stream output to an Icecast Server
• Multichannel Line-out
• Blank Detenction / Silence Detecter
• Auto Pilot a.k.a. Fallback Handling
• API to query Track-Service
• API to query monthly reports
• API to query data for a studio clock
• Web Application for displaying the Track-Service
• Web Application for displaying the studio clock

Read more on the Engine Features page.

Architecture

AURA Engine as part of the AURA Radio Suite uses an modulear architecture based on a REST API. All external information is retrieved using JSON data-structures.

To learn more, checkout the Engine Developer Guide or visit the Aura Meta repository.

Installation

Aura Engine runs on any modern Debian-based OS. It requires at least Node 13, Python 3.7.

You also need to install Liquidsoap 1.4.1 using OPAM.

Then do

git clone https://gitlab.servus.at/autoradio/engine

By default Aura Engine uses MariaDB for persistence. When starting the installation, please ensure you have root access to your database instance. The installation script automatically creates a database plus an associated user with password. If you want to use your own database system, select "Other / Manually" during the database installation step.

Development Environment

sudo ./install.sh

Production Environment

sudo ./install.sh prod

Configuration

In your development environment edit the file

./configuration/engine.ini

to configure the engine.

In production, or if the file exists, Engine uses the config location

/etc/aura/engine.ini

Read more about detailed settings in the Configuration Guide.

Running Engine

Development

While developing there is a simple convencience script run.sh to get you started. Call the engine's components in following order:

    ./run.sh      # Starts the engine-core component
    ./run.sh lqs  # Starts the engine-liquidsoap component
    ./run.sh api  # Starts the engine-api component

In development mode Engine uses the Flask development server. This server should not be used in your production environment.

Production

In production the process is slightly different to ensure the engine's components are always running i.e. restart themselves after some system restart or crash. Therefore they are executed using a system service:

  systemctl start aura-engine  
  systemctl start aura-lqs

and on system boot run following:

  systemctl enable aura-engine
  systemctl enable aura-lqs

API Server

For production Engine API uses the WSGI HTTP Server Gunicorn.

In production Gunicorn is used in combination with some proxy server, such as Nginx.

Although there are many HTTP proxies available, we strongly advise that you use Nginx. If you choose another proxy server you need to make sure that it buffers slow clients when you use default Gunicorn workers. Without this buffering Gunicorn will be easily susceptible to denial-of-service attacks. You can use Hey to check if your proxy is behaving properly. — Gunicorn Docs.

Supervisor is a preferable solution to run the gunicorn server in the background and also start it automatically on reboot.

Start the API service with Supervisor

    sudo supervisorctl reread
    sudo supervisorctl update
    sudo supervisorctl avail
    sudo supervisorctl restart engine-api

In case you want to reload whole supervisor service

    sudo service supervisor restart

Logging

All Engine logs for production can be found in /var/log/aura/engine

You can access the service logs using one of:

    journalctl -u aura-lqs
    journalctl -u aura-engine

About

Aura Engine is the play-out engine of the Aura Radio Software Suite. Aura stands for Automated Radio and is a swiss army knife for community radios. Beside the Engine it provides Steering (Admin Interface for the radio station), Dashboard (Collaborative scheduling and programme coordination), Tank (Audio uploading, pre-processing and delivery). Read more in the Aura Meta repository or on the specific project pages.

Steering	Dashboard	Tank	Engine

Resources

• Python: https://docs.python.org/
• Redis: https://redis.io/
• Liquidsoap: https://www.liquidsoap.info/doc-1.4.0/
• Jack Audio: https://jackaudio.org/
• Flask: https://palletsprojects.com/p/flask/
• Supervisor: http://supervisord.org/
• Gunicorn: https://gunicorn.org/