Spark Service

For user documentation, see https://www.brewblox.com

The Spark service handles connectivity for the BrewPi Spark controller.

This includes USB/TCP communication with the controller, but also encoding, decoding, and broadcasting data.

Installation

To set up the development environment, follow the instructions at https://brewblox.com/dev/service/python_env.html.

Tests

Integration tests run against the firmware simulator. This firmware is downloaded, but not committed. To ensure you have the latest firmware, run invoke download-firmware. This also happens during invoke update-firmware.

During tests, you may need to kill the pytest process. This will cause it to skip test teardown, and leave leftover containers and processes.
To remove these leftovers, run invoke testclean.

Firmware

The Spark service is coupled to a specific Spark firmware version. Version info is tracked in firmware.ini, and firmware binaries are downloaded during the Docker image build.

Protobuf message definitions are loaded from the Brewblox proto submodule at brewblox_devcon_spark/codec/proto. The firmware.ini file contains a sha for the relevant brewblox-proto commit.

The brewblox-proto repository only contains .proto files. The associated pb2.py files are compiled here and committed into version control.

Firmware dependency management is handled by invoke commands, defined in tasks.py:

invoke update-firmware fetches the latest firmware.ini file for a given firmware build (develop by default), checks out the associated brewblox-proto commit for the submodule, and then calls compile-proto and download-firmware.

invoke compile-proto compiles .proto files found in the proto submodule into _pb2.py python files. The_pb2.py files are committed into version control.

invoke download-firmware reads the version information in firmware.ini, and downloads the associated binary files into firmware/. The binary files are not committed into version control. Instead, they are re-downloaded during the CI build.

To update the service when making changes to firmware:

• Commit the firmware changes to the develop branch in the Brewblox firmware repository.
• Wait until the firmware CI build is done.
• Run invoke update-firmware
• Run pytest to verify that no code changes are required.
• Commit the changed files (firmware.ini, the proto submodule, and compiled _pb2.py files).