Added simple web page, routes are in a separate file

- Flask app factory instead of initializing `app` variable
- Gunicorn for production server
- Makefile: python3 -m
- .gitignore: instance dir

.gitignore

@@ -2,6 +2,7 @@ __pycache__/
 .mypy_cache/
 
 venv/
+instance/
 
 .vscode/
 .idea/

Makefile

@@ -1,8 +1,8 @@
 dev:
-	FLASK_DEBUG="true" flask run
+	FLASK_DEBUG="true" python3 -m flask run
 
 prod:
-	flask run
+	python3 -m gunicorn -w 4 "app:create_app()"
 
 format:
 	python3 -m autopep8 -r --in-place flaskapp/

app.py

@@ -1 +1 @@
-from flaskapp.app import app
+from flaskapp.app import create_app

flaskapp/__init__.py

@@ -1,3 +0,0 @@
-"""Init file for the module"""
-
-from .app import app

flaskapp/app.py

@@ -1,20 +1,39 @@
-"""Flask web application
-main script"""
+"""Flask web application main script"""
 
-from pathlib import Path
+import os
+import secrets
 
 from flask import Flask
 
+from . import routes
+from . import errors
 
-root = Path('..')
-static = str(root / 'static')
-tmpl = str(root / 'templates')
 
-app = Flask(
-    '${REPO_NAME_SNAKE}',
-    static_folder=static,
-    template_folder=tmpl,
-)
+def create_app() -> Flask:
+    """Flask app factory function"""
 
-if __name__ == '__main__':
-    app.run()
+    # Create an app object
+    app = Flask(
+        __name__,
+        static_folder='../static',
+        template_folder='../templates',
+        instance_relative_config=True,
+    )
+    # Get the token from environment
+    # or generate it using secrets
+    app.config['SECRET_KEY'] = os.getenv(
+        'SECRET_KEY',
+        secrets.token_hex(32),
+    )
+
+    # Create instance/ directory
+    try:
+        os.makedirs(app.instance_path)
+    except OSError:
+        pass
+
+    # Add routes
+    routes.add_routes(app)
+    errors.add_routes(app)
+
+    return app

flaskapp/errors.py

@@ -0,0 +1,48 @@
+"""Flask app error handlers"""
+
+from pathlib import Path
+
+from flask import Flask
+from flask import render_template
+
+# Add other HTTP error codes here
+CODES = [404, 500]
+
+
+def add_routes(app: Flask) -> None:
+    """Add all error handlers
+
+    Args:
+        app (Flask): Flask application
+    """
+
+    tmpl_dir = app.template_folder
+    if tmpl_dir is None:
+        return
+
+    tmpl = Path(__file__).parent / tmpl_dir
+
+    for code in CODES:
+        add_handler(app, tmpl, code)
+
+
+def add_handler(
+        app: Flask,
+        tmpl: Path,
+        code: int) -> None:
+    """Add Flask app error handler.
+    Only for internal use
+
+    Args:
+        app (Flask): Flask application
+        file (str): Template filename
+        code (int): Error code
+    """
+
+    file = f'{code}.html'
+
+    if (tmpl / file).exists():
+
+        @app.errorhandler(code)
+        def handler(_e):
+            return render_template(file), code

flaskapp/routes.py

@@ -0,0 +1,16 @@
+"""Main Flask app routes"""
+
+from flask import Flask
+from flask import render_template
+
+
+def add_routes(app: Flask) -> None:
+    """Add main routes
+
+    Args:
+        app (Flask): Flask application
+    """
+
+    @app.route('/')
+    def index():
+        return render_template('index.html')

requirements.txt

@@ -1 +1,2 @@
 flask==2.2.2
+gunicorn==20.1.0

static/css/style.css

@@ -0,0 +1,31 @@
+body {
+    height: 100vh;
+    padding: 0;
+    margin: 0;
+    font-family: sans-serif;
+
+    display: flex;
+    flex-direction: column;
+    justify-content: space-between;
+    align-items: center;
+
+    background: #fff;
+    color: #000;
+}
+
+@media (prefers-color-scheme: dark) {
+    body {
+        background: #202023;
+        color: #eee;
+    }
+}
+
+header { margin-top: 5px; }
+footer { margin-bottom: 5px; }
+
+a {
+    color: #5b8a55;
+}
+a:hover {
+    filter: brightness(120%);
+}

static/js/script.js

@@ -0,0 +1,4 @@
+addEventListener('load', () => {
+    document.getElementById('js')
+        .innerText = new Date().toLocaleString()
+})

templates/404.html

@@ -0,0 +1,11 @@
+{% extends "base.html" %}
+
+{% block title %}404{% endblock %}
+
+{% block content %}
+    <h1>404: Not Found</h1>
+    <p>
+        Go to the
+        <a href="/">main page</a>
+    </p>
+{% endblock %}

templates/500.html

@@ -0,0 +1,15 @@
+{% extends "base.html" %}
+
+{% block title %}500{% endblock %}
+
+{% block content %}
+    <h1>500: ISE</h1>
+    <p>
+        An error occured while
+        processing your request.
+    </p>
+    <p>
+        Please, try again later
+        or contact web site admin.
+    </p>
+{% endblock %}

templates/base.html

@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <meta name="description" content="${REPO_DESCRIPTION}">
+    <title>{% block title %}{% endblock %} | ${REPO_NAME}</title>
+    <link rel="stylesheet" href="/static/css/style.css">
+    <script src="/static/js/script.js"></script>
+</head>
+<body>
+    <header>${REPO_NAME}</header>
+    <article>
+        {% block content %}{% endblock %}
+    </article>
+    <footer id="js"></footer>
+</body>
+</html>

templates/index.html

@@ -0,0 +1,12 @@
+{% extends "base.html" %}
+
+{% block title %}Main page{% endblock %}
+
+{% block content %}
+    <h1>
+        This is the default main page of
+        <a href="https://git.dc09.ru/DarkCat09/tmpl-flask">
+            Flask app template
+        </a>
+    </h1>
+{% endblock %}