Allow TAP server to run under gunicorn with optional server extra (#30)

README.md

@@ -47,3 +47,13 @@ Notes:
    into documentation for ReadTheDocs works as expected. For more information, see
    the Python Project Template documentation on
    [Sphinx and Python Notebooks](https://lincc-ppt.readthedocs.io/en/latest/practices/sphinx.html#python-notebooks)
+
+## Running the TAP server with gunicorn
+
+Install the optional server extra (or install `gunicorn` separately), then run gunicorn
+against the provided WSGI callable:
+
+```
+pip install 'hats-tap[server]'
+gunicorn "hats_tap.tap_server:application" --bind 0.0.0.0:43213
+```

pyproject.toml

@@ -42,6 +42,9 @@ dev = [
     "pytest-cov", # Used to report total code coverage
     "ruff", # Used for static linting of files
 ]
+server = [
+    "gunicorn>=22.0.0", # Optional WSGI server for production use
+]
 
 [build-system]
 requires = [

src/hats_tap/tap_server.py

@@ -27,6 +27,15 @@
 app = Flask(__name__)
 
 
+def create_app():
+    """Return the Flask application for use with WSGI servers such as gunicorn."""
+    return app
+
+
+# Default WSGI callable name expected by gunicorn when no object is specified.
+application = app
+
+
 # Log what the client is actually sending
 @app.before_request
 def log_request_info():

tests/hats_tap/test_tap_server_wsgi.py

@@ -0,0 +1,10 @@
+"""Tests for WSGI compatibility of the TAP server."""
+
+from hats_tap import tap_server
+
+
+def test_wsgi_app_exports():
+    """The tap_server module should expose a WSGI callable for gunicorn."""
+    wsgi_app = tap_server.create_app()
+    assert wsgi_app is tap_server.app
+    assert tap_server.application is tap_server.app