flask to fastapi conversion

pyproject.toml

@@ -8,14 +8,14 @@ packages = [{ include = "src" }]
 
 [tool.poetry.dependencies]
 # command: `poetry add <package-name>`
-python = ">3.9.7"
+python = ">=3.10"
 flask = "3.0.3"
 flask-cors = "5.0.0"
 g4f = "0.3.2.2"
 geopy = "2.4.1"
 openmeteo-requests = "1.2.0"
 pandas = "2.2.2"
-pydantic = "2.7.2"
+pydantic = "^2.12.5"
 pydantic-settings = "2.2.1"
 python-dotenv = "1.0.1"
 requests = "2.32.4"
@@ -30,6 +30,9 @@ matplotlib = "3.9.0"
 seaborn = "^0.13.2"
 numpy = "^1.26.4"
 pymongo = {extras = ["gssapi", "snappy", "srv", "tls"], version = "^4.15.4"}
+fastapi = "^0.135.2"
+uvicorn = "^0.42.0"
+httpx = "^0.28.1"
 
 [tool.poetry.group.dev.dependencies]
 # command: `poetry add --group dev <package-name>`

src/server.py

@@ -1,84 +1,84 @@
 """
-Flask Server!
+FastAPI Server!
 """
 
 import logging
 import subprocess
 import sys
-import urllib.parse
 from pathlib import Path
 
-from flask import (
-    Flask,
-    render_template,
-    request,
-    send_file,
-    send_from_directory,
-)
-from flask_cors import CORS
+import uvicorn
+from fastapi import FastAPI, HTTPException, Request
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import FileResponse, PlainTextResponse
+from fastapi.templating import Jinja2Templates
 
 from src.settings import ServerSettings
 
 logger = logging.getLogger(__name__)
 
+BASE_DIR = Path(__file__).resolve().parent.parent
+TEMPLATES_DIR = BASE_DIR / "src" / "templates"
+CLI_PATH = BASE_DIR / "src" / "cli.py"
+
+templates = Jinja2Templates(directory=str(TEMPLATES_DIR))
+
 
 def create_app(env):
     """
     Application factory function
     """
-    app = Flask(__name__)
-    CORS(app)
+    app = FastAPI()
+
+    # define which "origins" (frontend urls) can talk to this api
+    origins = ["http://localhost:8501", "http://127.0.0.1:8501"]
+
+    app.add_middleware(
+        CORSMiddleware,
+        allow_origins=origins,
+        allow_credentials=True,
+        allow_methods=["GET"],
+        allow_headers=["*"],
+    )
 
-    @app.route("/help")
-    def serve_help():
+    @app.get("/help")
+    async def serve_help():
         """Serves the help.txt file."""
-        return send_from_directory(
-            Path(__file__).resolve().parents[1], "help.txt"
-        )
-
-    @app.route("/home")
-    def serve_index():
-        """Serves index.html."""
-        return render_template("index.html", env_vars=env.model_dump())
-
-    @app.route("/script.js")
-    def serve_script():
-        """Serves the frontend JavaScript."""
-        return send_file("static/script.js")
-
-    @app.route("/")
-    def default_route():
+        HELP_FILE_PATH = BASE_DIR / "help.txt"
+        return FileResponse(path=HELP_FILE_PATH, media_type="text/plain")
+
+    @app.get("/", response_class=PlainTextResponse)
+    async def default_route(request: Request):
         """Serves the surf report."""
-        query_parameters = urllib.parse.parse_qsl(
-            request.query_string.decode(), keep_blank_values=True
-        )
         parsed_parameters = [
             f"{key}={value}" if value else key
-            for key, value in query_parameters
+            for key, value in request.query_params.items()
         ]
         args = ",".join(parsed_parameters)
 
         try:
             result = subprocess.run(
-                [sys.executable, Path("src") / "cli.py", args],
+                [sys.executable, str(CLI_PATH), args],
                 capture_output=True,
                 text=True,
                 check=True,
             )
             return result.stdout
         except subprocess.CalledProcessError as e:
             logger.error("Subprocess error: %s", e.stderr)
-            raise
+            raise HTTPException(status_code=500, detail="Internal CLI Error")
 
     return app
 
 
+env = ServerSettings()
+app = create_app(env)
+
 if __name__ == "__main__":  # pragma: no cover
     logging.basicConfig(
         level=logging.INFO,
         format="%(asctime)s [%(levelname)s] %(name)s: %(message)s",
         datefmt="%Y-%m-%d %H:%M:%S",
     )
-    env = ServerSettings()
-    app = create_app(env)
-    app.run(host="0.0.0.0", port=env.PORT, debug=env.DEBUG)
+
+    uvicorn.run(app, host=str(env.IP_ADDRESS), port=env.PORT)

src/settings.py

@@ -28,7 +28,6 @@ class ServerSettings(CommonSettings):
     IP_ADDRESS: Union[IPvAnyAddress | Literal["localhost"]] = Field(
         default="localhost"
     )
-    DEBUG: bool = Field(default=True)
 
 
 class EmailSettings(ServerSettings):

src/templates/index.html

@@ -86,8 +86,8 @@
       </div>
     </div>
     <script>
-      // load .env variables from Flask server
-      const env = {{ env_vars|tojson }};
+      // load .env variables from FastAPI server
+      const env = {{ env_vars | safe }};
     </script>
     <script src="{{ url_for('serve_script') }}"></script>
   </body>

tests/test_help_endpoint.py

@@ -1,5 +1,7 @@
 from http import HTTPStatus
 
+from fastapi.testclient import TestClient
+
 from src.server import create_app
 from src.settings import ServerSettings
 
@@ -8,8 +10,8 @@ def test_help_endpoint_returns_200():
     env = ServerSettings()
     app = create_app(env)
 
-    client = app.test_client()
+    client = TestClient(app)
     resp = client.get("/help")
 
     assert resp.status_code == HTTPStatus.OK
-    assert len(resp.data) > 0
+    assert len(resp.text) > 0

tests/test_root.py

@@ -1,6 +1,8 @@
 import subprocess
 from http import HTTPStatus
 
+from fastapi.testclient import TestClient
+
 from src.server import create_app
 from src.settings import ServerSettings
 
@@ -18,8 +20,8 @@ def fake_run(*args, **kwargs):
 
     monkeypatch.setattr(subprocess, "run", fake_run)
 
-    client = app.test_client()
+    client = TestClient(app)
     resp = client.get("/")
 
     assert resp.status_code == HTTPStatus.OK
-    assert b"ok" in resp.data
+    assert "ok" in resp.text

tests/test_server.py

@@ -4,7 +4,8 @@
 
 import subprocess
 from http import HTTPStatus
-from unittest.mock import patch
+
+from fastapi.testclient import TestClient
 
 from src.server import create_app
 from src.settings import ServerSettings
@@ -14,23 +15,6 @@ def _make_app():
     return create_app(ServerSettings())
 
 
-def test_serve_index_returns_200(monkeypatch):
-    """GET /home renders the index template and returns 200."""
-    app = _make_app()
-    with patch("src.server.render_template", return_value="<html>home</html>"):
-        resp = app.test_client().get("/home")
-    assert resp.status_code == HTTPStatus.OK
-    assert b"<html>home</html>" in resp.data
-
-
-def test_serve_script_returns_200(monkeypatch):
-    """GET /script.js serves the JavaScript file and returns 200."""
-    app = _make_app()
-    with patch("src.server.send_file", return_value="console.log('ok')"):
-        resp = app.test_client().get("/script.js")
-    assert resp.status_code == HTTPStatus.OK
-
-
 def test_root_subprocess_error_returns_500(monkeypatch):
     """GET / returns 500 and logs the error when the subprocess fails."""
     app = _make_app()
@@ -39,5 +23,5 @@ def fail_run(*args, **kwargs):
         raise subprocess.CalledProcessError(1, "cmd", stderr="boom")
 
     monkeypatch.setattr(subprocess, "run", fail_run)
-    resp = app.test_client().get("/")
+    resp = TestClient(app).get("/")
     assert resp.status_code == HTTPStatus.INTERNAL_SERVER_ERROR