Refactor to async TimescaleDB backend & add Alembic migrations

alembic/env.py

@@ -0,0 +1,60 @@
+import os
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config, pool
+from alembic import context
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the DATABASE_URL env var, if set; else fall back to ini file
+database_url = os.getenv('DATABASE_URL', config.get_main_option('sqlalchemy.url'))
+config.set_main_option('sqlalchemy.url', database_url)
+
+# Interpret log config
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+from db_async import metadata  # noqa
+target_metadata = metadata
+
+
+def run_migrations_offline():
+    '''Run migrations in 'offline' mode.'''  # noqa
+    url = config.get_main_option('sqlalchemy.url')
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online():
+    '''Run migrations in 'online' mode.'''  # noqa
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix='sqlalchemy.',
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection,
+            target_metadata=target_metadata,
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()