Adding async backend example that mirrors the current synchronous backend

.env

@@ -35,6 +35,8 @@ SMTP_PORT=587
 POSTGRES_SERVER=localhost
 POSTGRES_PORT=5432
 POSTGRES_DB=app
+POSTGRES_DB_ASYNC=app_async #create separate db for backend_async using psycopg 3.12 and pwdlib[argon2]
+POSTGRES_TEST_DB=app_async_test #demonstrate separate test db setup
 POSTGRES_USER=postgres
 POSTGRES_PASSWORD=changethis
 

backend_async/.dockerignore

@@ -0,0 +1,8 @@
+# Python
+__pycache__
+app.egg-info
+*.pyc
+.mypy_cache
+.coverage
+htmlcov
+.venv

backend_async/.gitignore

@@ -0,0 +1,8 @@
+__pycache__
+app.egg-info
+*.pyc
+.mypy_cache
+.coverage
+htmlcov
+.cache
+.venv

backend_async/.python-version

@@ -0,0 +1 @@
+3.13

backend_async/Dockerfile

@@ -0,0 +1,44 @@
+FROM python:3.13-slim
+
+ENV PYTHONUNBUFFERED=1
+
+WORKDIR /app/
+
+# Install uv
+# Ref: https://docs.astral.sh/uv/guides/integration/docker/#installing-uv
+COPY --from=ghcr.io/astral-sh/uv:0.5.11 /uv /uvx /bin/
+
+# Place executables in the environment at the front of the path
+# Ref: https://docs.astral.sh/uv/guides/integration/docker/#using-the-environment
+ENV PATH="/app/.venv/bin:$PATH"
+
+# Compile bytecode
+# Ref: https://docs.astral.sh/uv/guides/integration/docker/#compiling-bytecode
+ENV UV_COMPILE_BYTECODE=1
+
+# uv Cache
+# Ref: https://docs.astral.sh/uv/guides/integration/docker/#caching
+ENV UV_LINK_MODE=copy
+
+# Install dependencies
+# Ref: https://docs.astral.sh/uv/guides/integration/docker/#intermediate-layers
+RUN --mount=type=cache,target=/root/.cache/uv \
+    --mount=type=bind,source=uv.lock,target=uv.lock \
+    --mount=type=bind,source=pyproject.toml,target=pyproject.toml \
+    uv sync --frozen --no-install-project
+
+ENV PYTHONPATH=/app
+
+COPY ./scripts /app/scripts
+
+COPY ./pyproject.toml ./uv.lock ./alembic.ini /app/
+
+COPY ./app /app/app
+COPY ./tests /app/tests
+
+# Sync the project
+# Ref: https://docs.astral.sh/uv/guides/integration/docker/#intermediate-layers
+RUN --mount=type=cache,target=/root/.cache/uv \
+    uv sync
+
+CMD ["fastapi", "run", "--workers", "4", "app/main.py"]

backend_async/README.md

@@ -0,0 +1,61 @@
+# FastAPI Project - Backend Async
+
+## Requirements
+
+* [Docker](https://www.docker.com/).
+* [uv](https://docs.astral.sh/uv/) for Python package and environment management.
+
+## Quick Start
+
+By default, the dependencies are managed with [uv](https://docs.astral.sh/uv/), go there and install it.
+
+From `./backend_async/` you can install all the dependencies with:
+
+```console
+$ uv sync
+```
+
+Then you can activate the virtual environment with:
+
+```console
+$ source .venv/bin/activate
+```
+
+Make sure your editor is using the correct Python virtual environment, with the interpreter at `backend_async/.venv/bin/python`.
+
+Start database containers and migrate:
+
+```console
+$ docker compose up -d db
+$ alembic upgrade head
+```
+
+Start development server:
+
+```console
+$ fastapi dev
+```
+
+Modify or add SQLModel models for data and SQL tables in `./backend_async/app/models.py`, API endpoints in `./backend_async/app/api/`, CRUD (Create, Read, Update, Delete) utils in `./backend_async/app/crud.py`.
+
+## Tests
+
+Async tests are run using anyio backend. Here we also demonstrate setup using a separate test database, so ensure that the database container is up and running (see Quick Start).
+
+From `./backend_async/` you can run:
+
+```console
+$ pytest
+```
+
+For coverage:
+
+```console
+$ coverage run -m pytest
+```
+
+To view coverage report:
+
+```console
+$ coverage report -m
+```

backend_async/alembic.ini

@@ -0,0 +1,147 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts.
+# this is typically a path given in POSIX (e.g. forward slashes)
+# format, relative to the token %(here)s which refers to the location of this
+# ini file
+script_location = %(here)s/app/alembic
+
+# template used to generate migration file names; The default value is %%(rev)s_%%(slug)s
+# Uncomment the line below if you want the files to be prepended with date and time
+# see https://alembic.sqlalchemy.org/en/latest/tutorial.html#editing-the-ini-file
+# for all available tokens
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(rev)s_%%(slug)s
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.  for multiple paths, the path separator
+# is defined by "path_separator" below.
+prepend_sys_path = .
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the tzdata library which can be installed by adding
+# `alembic[tz]` to the pip requirements.
+# string value is passed to ZoneInfo()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; This defaults
+# to <script_location>/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path.
+# The path separator used here should be the separator specified by "path_separator"
+# below.
+# version_locations = %(here)s/bar:%(here)s/bat:%(here)s/alembic/versions
+
+# path_separator; This indicates what character is used to split lists of file
+# paths, including version_locations and prepend_sys_path within configparser
+# files such as alembic.ini.
+# The default rendered in new alembic.ini files is "os", which uses os.pathsep
+# to provide os-dependent path splitting.
+#
+# Note that in order to support legacy alembic.ini files, this default does NOT
+# take place if path_separator is not present in alembic.ini.  If this
+# option is omitted entirely, fallback logic is as follows:
+#
+# 1. Parsing of the version_locations option falls back to using the legacy
+#    "version_path_separator" key, which if absent then falls back to the legacy
+#    behavior of splitting on spaces and/or commas.
+# 2. Parsing of the prepend_sys_path option falls back to the legacy
+#    behavior of splitting on spaces, commas, or colons.
+#
+# Valid values for path_separator are:
+#
+# path_separator = :
+# path_separator = ;
+# path_separator = space
+# path_separator = newline
+#
+# Use os.pathsep. Default configuration used for new projects.
+path_separator = os
+
+
+# set to 'true' to search source files recursively
+# in each "version_locations" directory
+# new in Alembic version 1.10
+# recursive_version_locations = false
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+# database URL.  This is consumed by the user-maintained env.py script only.
+# other means of configuring database URLs may be customized within the env.py
+# file.
+sqlalchemy.url = driver://user:pass@localhost/dbname
+
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks = black
+# black.type = console_scripts
+# black.entrypoint = black
+# black.options = -l 79 REVISION_SCRIPT_FILENAME
+
+# lint with attempts to fix using "ruff" - use the module runner, against the "ruff" module
+# hooks = ruff
+# ruff.type = module
+# ruff.module = ruff
+# ruff.options = check --fix REVISION_SCRIPT_FILENAME
+
+# Alternatively, use the exec runner to execute a binary found on your PATH
+# hooks = ruff
+# ruff.type = exec
+# ruff.executable = ruff
+# ruff.options = check --fix REVISION_SCRIPT_FILENAME
+
+# Logging configuration.  This is also consumed by the user-maintained
+# env.py script only.
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARNING
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARNING
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

backend_async/app/alembic/README

@@ -0,0 +1 @@
+Generic single-database configuration with an async dbapi.

backend_async/app/alembic/env.py

@@ -0,0 +1,100 @@
+import asyncio
+from logging.config import fileConfig
+
+from sqlalchemy import pool
+from sqlalchemy.engine import Connection
+from sqlalchemy.ext.asyncio import async_engine_from_config
+
+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 config file for Python logging.
+# This line sets up loggers basically.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+# target_metadata = None
+
+from app.models import SQLModel  # noqa
+from app.core.config import settings # noqa
+
+target_metadata = SQLModel.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+def get_url():
+    return str(settings.SQLALCHEMY_DATABASE_URI)
+
+
+def run_migrations_offline() -> None:
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    # url = config.get_main_option("sqlalchemy.url")
+    url = get_url()
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def do_run_migrations(connection: Connection) -> None:
+    context.configure(connection=connection, target_metadata=target_metadata)
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+async def run_async_migrations() -> None:
+    """In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    configuration = config.get_section(config.config_ini_section, {})
+    configuration["sqlalchemy.url"] = get_url()
+
+    connectable = async_engine_from_config(
+        configuration,
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    async with connectable.connect() as connection:
+        await connection.run_sync(do_run_migrations)
+
+    await connectable.dispose()
+
+
+def run_migrations_online() -> None:
+    """Run migrations in 'online' mode."""
+
+    asyncio.run(run_async_migrations())
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()