The websocket service is no longer provided by a different service,
controlled by a different thread running on another port.
Instead, it's now exposed directly over Flask routes, using
WSGI+eventlet+simple_websocket.
Also, the SSL context options have been removed from `backend.http`, for
sake of simplicity. If you want to enable SSL, you can serve Platypush
through a reverse proxy like nginx.
Added `waitress` dependency. For performance and security reasons, it's
better to always run the Flask application inside of a uWSGI server.
`waitress` also makes things easier by avoiding to ask the user to
manually provide the external executable arguments, as it was the case
with `uwsgi` and `gunicorn`.
Added Alembic environment and `run_db_migrations` logic to the entities
engine so database schema changes can be processed as soon as the
application is started.
SQLAlchemy 2 has introduced several breaking changes that can break
several things in the application - especially where the code uses
`connection.execute()` with raw SQL statements.
We need to temporarily force the installation of versions from the 1.x
branch, while migrating the existing code to the new version.
PyJWT is a very brittle and cumbersome dependency that expects several
cryptography libraries to be already installed on the system, and it can
lead to hard-to-debug errors when ported to different systems.
Moreover, it installs the whole `cryptography` package, which is several
MBs in size, takes time to compile, and it requires a Rust compiler to
be present on the target machine.
Platypush will now use the Python-native `rsa` module to handle JWT
tokens.
If Platypush is supposed to work also without a manually created
`config.yaml`, and the HTTP backend is enabled by default in that
configuration, then Flask and companions should be among the required
dependencies.
