Pump GCN Classic notices to a Kafka broker.

GCN Classic sends binary and VOEvent format notices to us over TCP/IP. We act as the server and GCN Classic acts as the client. The packet format consists of the following fields:

1. The 160-byte binary notice. The first 4 bytes are the notice type as a network byte order integer.
2. A 4-byte network byte order integer that is the length of the VOEvent.
3. The VOEvent.
4. A 4-byte network byte order integer that is the length of the text notice.
5. The text notice.

GCN Classic does not expect us to send any data back. GCN sends a packet at least every 60 seconds, including keepalive packets. Keepalive packets have the same format as notice packets, except that the notice type is gcn.NoticeType.IM_ALIVE, gcn.NoticeType.VOE_11_IM_ALIVE, or gcn.NoticeType.VOE_20_IM_ALIVE.

Because this protocol does not have any authentication, it must be tunneled using a tool like ssh or stunnel.

This package uses Poetry for packaging and Python virtual environment management. To get started:

1. Fork and clone this repository.

2. Install pre-commit hooks by running the following two commands:

   pip install pre-commit
   pre-commit install
   

3. Install Poetry by following their installation instructions.

4. Install this package and its dependencies by running the following command inside your clone of this repository:

   poetry install --all-extras
   

5. Run the following command to launch a shell that is preconfigured with the project's virtual environment:

   poetry shell
   

By default, metrics for Prometheus are provided on port 8000.