External Server

Directory contains fake external server the communicates with external client, which is part of the module gateway.

Fleet protocol deviations

• This implementation of External server can handle only one car. To handle multiple cars, more instances of this External server must be created. This is a deviation from Fleet protocol where one External server instance can handle multiple cars.

Requirements

• Python (version >= 3.10)
• Other python requirements can be installed by pip3 install -r requirements.txt
• In directory external_server/modules/car_accessory_module run following commands:
  • mkdir build
  • cd build
  • cmake ..
  • make

Arguments

• -c or --config <str> = path to the config file, default = ./config/config.json
• --tls = tls mqtt authentication

TLS arguments

following arguments are used if argument tls is set:

• --ca <str> = path to ca certification
• --cert <str> = path to cert file
• --key <str> = path to key file

Usage

Prepare your shared library of module implementation (implementation of external_server_api.h). To use this library with External server, you need to fill the module number and path to this library into External server config file.

Options in config file

• company_name, car_name (required) - used for MQTT topics name, should be same as in module gateway; only lowercase characters, numbers and underscores are allowed
• mqtt_address (required) - IP address of the MQTT broker
• mqtt_port (required) - port of the MQTT broker
• mqtt_timeout (in seconds) - timeout for getting message from MqttClient
• timeout (in seconds) - Maximum time amount between Status and Command messages
• send_invalid_command - sends command to Module gateway even if External server detects invalid command returned from external_server_api; affects only normal communication
• sleep_duration_after_connection_refused - if connection to Module gateway was refused, External server will sleep for defined duration before next connection attempt is proceed
• log_files_directory (required) - path to a directory in which the logs will be stored. If left empty, the current working directory will be used
• log_files_to_keep (required) - number of log files that will be kept (can be 0)
• log_file_max_size_bytes (required) - max file size of a log in bytes (0 means unlimited)
• modules (required) - supported modules specified by module number
  • lib_path (required) - path to module shared library
  • config (optional) - specification of config for module, any key-value pairs will be forwarded to module implementation init function; when empty or missing, empty config forwarded to init function

Example of config file

{
   "company_name": "bringauto",
   "car_name": "virtual_vehicle",
   "mqtt_address": "127.0.0.1",
   "mqtt_port": 1883,
   "mqtt_timeout": 30,
   "timeout": 30,
   "send_invalid_command": false,
   "sleep_duration_after_connection_refused": 0.5,
   "log_files_directory": "/path/to/logs/directory",
   "log_files_to_keep": 5,
   "log_file_max_size_bytes": 50000,
   "modules": {
       "2" : {
           "lib_path": "/path/to/module/library/with/number/2",
           "config": {
               "ip": "172.0.1.1",
               "port": "4242"
           }
       },
       "3" : {
           "lib_path": "/path/to/module/library/with/number/3",
           "config": {}
       }
   }
}

After filling the config, you can run External server with this command:

python3 main.py

Unit tests

Unit tests are covering classes in external_server/checker direcory. Tests are using pytest. With installed pytest run this:

python -m pytest

Docker

The External server is ready to use with docker. You can build docker image with docker build . in this directory. The Dockerfile also describes compiling these Bringauto modules:

• module 3 - IO module

These compiled modules are inserted into image and are ready to use with External server in docker container.

The External server can be also used with docker compose. In the docker-compose.yml is example of External server service, which can't be used alone and should be inserted into another docker-compose.yml with MQTT service and defined network. This specific example assumes that MQTT broker is service named mosquitto and defined network is bring-emulator.