Add the basics

Dockerfile

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+# Build an intermediate image for the Python requirements
+FROM python:3.9-slim-buster as intermediate
+
+# Install Git and Python requirements
+RUN apt update && apt install -y build-essential
+COPY requirements.txt .
+RUN python -m pip install --user -r requirements.txt
+
+# Start from a fresh image
+FROM python:3.9-slim-buster
+
+# Keeps Python from generating .pyc files in the container
+ENV PYTHONDONTWRITEBYTECODE=1
+
+# Turns off buffering for easier container logging
+ENV PYTHONUNBUFFERED=1
+
+RUN useradd -u 4000 -d /app appuser
+WORKDIR /app
+
+# Copy over the Python requirements from the intermediate container
+COPY --from=intermediate /root/.local /app/.local
+
+RUN chown -R appuser: /app
+
+USER appuser
+
+# Set the main execution command
+ENTRYPOINT [".local/bin/waitress-serve", "main:app"]
+# HEALTHCHECK --interval=5s --timeout=30s --start-period=5s --retries=3 CMD [ "/app/healthcheck.sh" ]
+EXPOSE 8080/tcp
+
+# Copy in the code
+COPY slinky slinky/
+COPY templates templates/
+COPY main.py .

docker-compose.yaml

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+---
+version: "3"
+services:
+  slinky:
+    container_name: slinky
+    build:
+      context: .
+    image: slinky:latest
+    networks:
+      - traefik
+    labels:
+      - traefik.enable=true
+      - traefik.http.routers.slinky.entrypoints=web
+      - traefik.http.routers.slinky.service=slinky
+      - traefik.http.services.slinky.loadbalancer.server.port=8080
+    restart: unless-stopped
+
+networks:
+  traefik:
+    external:
+      name: traefik_internal

main.py

@@ -1,16 +1,23 @@
-import sys
+"""
+Main Flask-based app for Slinky
+"""
+from flask import Flask, render_template
+from flask_bootstrap import Bootstrap
 
-from flask.wrappers import Response
+from slinky.web import slinky_webapp
+
+app = Flask(__name__)
+app.register_blueprint(slinky_webapp)
+
+Bootstrap(app)
 
 
-def url_home() -> Response:
+@app.route('/')
-    ...
+def index() -> str:
+    """
+    Index/Landing page
 
-
+    Returns:
-if __name__ == '__main__':
+        str: string of page content
-
+    """
-    def main() -> int:
+    return render_template('index.html')
-        # Start Flask
-        return 0
-
-    sys.exit(main())

requirements.txt

@@ -1 +1,5 @@
 flask
+flask_bootstrap
+flask_wtf
+waitress
+Flask-SQLAlchemy

slinky/__init__.py

@@ -1,7 +1,58 @@
+"""
+Main code
+"""
+
 import random
 import string
+from datetime import datetime
+from typing import Optional
+
+from slinky import db
+
 
 def random_string(length: int = 4) -> str:
+    """
+    Create a random, alphanumeric string of the length specified
+
+    Args:
+        length (int, optional): length of string to generate. Defaults to 4.
+
+    Returns:
+        str: random alphanumeric string
+    """
     allowed_chars: str = string.ascii_letters + string.digits
 
     return ''.join(random.SystemRandom().choice(allowed_chars) for _ in range(length))
+
+
+def add_shortcode(
+    url: str,
+    length: int = 4,
+    fixed_views: int = 0,
+    expiry: datetime = datetime.max,
+) -> str:
+    """
+    Add a shortcode to the DB
+
+    Args:
+        url (str): URL to redirect to
+        fixed_views (int, optional): number of views to serve before expiring.
+            Defaults to 0 (no limit).
+        expiry (int, optional): date of expiry. Defaults to 0 (no limit).
+
+    Returns:
+        str: shortcode for the redirect
+    """
+    session = db.session()
+    shortcode = random_string(length=length)
+    dbentry = db.ShortURL(
+        shortcode=shortcode,
+        url=url,
+        fixed_views=fixed_views,
+        expiry=expiry,
+    )
+    session.add(dbentry)
+    session.commit()
+    session.close()
+
+    return shortcode

slinky/db.py

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+"""
+DB component
+"""
+from sqlalchemy import Column, Integer, String, create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import Session, sessionmaker
+
+Base = declarative_base()
+
+
+class ShortURL(Base):  # pylint: disable=too-few-public-methods
+    """
+    Class to describe the DB schema for ShortURLs
+    """
+
+    __tablename__ = 'shorturl'
+
+    id = Column(Integer, primary_key=True)
+    shortcode = Column(String(128), unique=True, nullable=False)
+    url = Column(String(2048), unique=False, nullable=False)
+    fixed_views = Column(Integer, unique=False, nullable=False)
+    expiry = Column(Integer, unique=False, nullable=False)
+
+
+def session() -> Session:
+    """
+    Create a DB session
+
+    Returns:
+        Session: the DB session object
+    """
+    engine = create_engine('sqlite:////tmp/test.db')
+    Base.metadata.create_all(engine)
+    new_session = sessionmaker(bind=engine)
+    return new_session()

slinky/templates/add.html

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+{% include '_head.html' %}
+
+<!-- Begin page content -->
+<main class="container">
+    <div class="container">
+        <h1 class="mt-5">Add a shortcode</h1>
+    </div>
+    <br />
+    <form action="/add" method="post">
+        {{ form.url.label }} {{ form.url }}<br />
+        {{ form.length.label }} {{ form.length }}<br />
+        {{ form.fixed_views.label }} {{ form.fixed_views }} (0 = unlimited)<br />
+        {{ form.expiry.label}} {{ form.expiry(class='datepicker') }} (leave as default for unlimited)<br />
+
+        <button id="submit" class="btn btn-primary" type="submit" onclick="waiting();" style="margin: 1em 0;">
+            Create shortcode
+            <span class="spinner-border spinner-border-sm" role="status" aria-hidden="true"></span>
+        </button>
+    </form>
+
+    <div id="content">
+        {% if shortcode -%}
+        <table class="table table-striped table-sm">
+            <thead>
+                <tr>
+                    <th scope="col">Short URL</th>
+                </tr>
+            </thead>
+            <tbody>
+                <tr>
+                    <td>{{request.host_url}}{{ shortcode }}</td>
+                </tr>
+            </tbody>
+        </table>
+        {% endif -%}
+    </div>
+</main>
+
+{% include '_tail.html' %}

slinky/web.py

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+"""
+Web component
+"""
+
+from datetime import datetime
+
+from flask import Blueprint, render_template
+from flask_wtf import FlaskForm
+from wtforms import DateTimeLocalField, IntegerField, StringField
+from wtforms.validators import DataRequired, Length
+
+from slinky import add_shortcode
+
+slinky_webapp = Blueprint('webapp', __name__, template_folder='templates')
+
+
+class ShortURLForm(FlaskForm):  # type: ignore[misc]
+    """
+    Web form definition
+    """
+
+    url = StringField(
+        'URL',
+        validators=[DataRequired(), Length(1, 2048)],
+        render_kw={
+            'size': 64,
+            'maxlength': 2048,
+            'placeholder': 'e.g. www.example.com',
+        },
+    )
+    fixed_views = IntegerField(
+        'Fixed number of views',
+        validators=[DataRequired()],
+        render_kw={
+            'size': 3,
+            'value': 0,
+        },
+    )
+    length = IntegerField(
+        'Shortcode length',
+        validators=[DataRequired()],
+        render_kw={
+            'size': 3,
+            'value': 4,
+        },
+    )
+    expiry = DateTimeLocalField(
+        'Expiry',
+        format='%Y-%m-%dT%H:%M',
+        render_kw={
+            'size': 8,
+            'maxlength': 10,
+        },
+    )
+
+
+@slinky_webapp.route('/add', methods=['GET', 'POST'])
+def add() -> str:
+    """
+    Create and add a new shorturl
+
+    Returns:
+        str: shortcode for the URL
+    """
+    shortcode = ''
+    url = ''
+
+    form = ShortURLForm(meta={'csrf': False})
+
+    if form.is_submitted():
+        url = form.url.data.strip()
+        length = form.length.data
+        fixed_views = form.fixed_views.data
+        expiry = form.expiry.data or datetime.max
+
+    if url:
+        shortcode = add_shortcode(url, length, fixed_views, expiry)
+
+    return render_template('add.html', form=form, shortcode=shortcode)

templates/_head.html

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+<!doctype html>
+<html lang="en">
+
+<head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <meta name="description" content="">
+
+    <title>Slinky</title>
+
+    <link rel="canonical" href="https://getbootstrap.com/docs/5.0/examples/navbar-static/">
+
+    <!-- Bootstrap CSS -->
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0-beta3/dist/css/bootstrap.min.css" rel="stylesheet"
+        integrity="sha384-eOJMYsd53ii+scO/bJGFsiCZc+5NDVN2yr8+0RDqr0Ql0h+rP48ckxlpbzKgwra6" crossorigin="anonymous">
+    <link rel="stylesheet" href="{{url_for('bootstrap.static', filename='datepicker.css')}}">
+    <meta name="theme-color" content="#7952b3">
+
+    <style>
+        .bd-placeholder-img {
+            font-size: 1.125rem;
+            text-anchor: middle;
+            -webkit-user-select: none;
+            -moz-user-select: none;
+            user-select: none;
+        }
+
+        .badge a {
+            color: white;
+            text-decoration: none;
+        }
+
+        .badge.text-dark a {
+            color: black;
+        }
+
+        @media (min-width: 768px) {
+            .bd-placeholder-img-lg {
+                font-size: 3.5rem;
+            }
+        }
+
+        [role=status] {
+            display: none;
+        }
+
+        .tooltip>.tooltip-inner {
+            max-width: 60em !important;
+            text-align: left !important;
+        }
+
+        .highlight {
+            background-color: #f48024;
+            color: #1d1d1e;
+            border-radius: 2px;
+            -webkit-box-decoration-break: clone;
+            box-decoration-break: clone;
+            padding: 0 1px 0 1px;
+        }
+
+        .checkboxlist ul {
+            list-style-type: none;
+            margin: 0;
+            padding: 1em;
+        }
+    </style>
+
+    <!-- Custom styles for this template -->
+    <!-- <link href="navbar-top.css" rel="stylesheet"> -->
+    <script>
+        // <![CDATA[
+        function waiting() {
+            document.querySelectorAll('[role="status"]')[0].style.display = "inline-block";
+        }
+      // ]]>
+    </script>
+</head>
+
+<body>
+    <nav class="navbar navbar-expand-md navbar-dark bg-dark mb-4">
+        <div class="container-fluid">
+            <a class="navbar-brand" href="/">Slinky</a>
+            <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarCollapse"
+                aria-controls="navbarCollapse" aria-expanded="false" aria-label="Toggle navigation">
+                <span class="navbar-toggler-icon"></span>
+            </button>
+            <div class="collapse navbar-collapse" id="navbarCollapse">
+                <ul class="navbar-nav me-auto mb-2 mb-md-0">
+                    <li class="nav-item">
+                        <a class="nav-link" href="/add">Add</a>
+                    </li>
+                </ul>
+            </div>
+        </div>
+    </nav>

templates/_tail.html

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+<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0-beta3/dist/js/bootstrap.bundle.min.js"
+    integrity="sha384-JEW9xMcG8R+pH31jmWH6WWP0WintQrMb4s7ZOdauHnUtxwoG2vI5DkLtS3qm9Ekf" crossorigin="anonymous">
+    </script>
+<script>
+    var tooltipTriggerList = [].slice.call(document.querySelectorAll('[data-bs-toggle="tooltip"]'));
+    var tooltipList = tooltipTriggerList.map(function (tooltipTriggerEl) {
+        return new bootstrap.Tooltip(tooltipTriggerEl);
+    });
+</script>
+</body>
+
+</html>

templates/index.html

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+{% include '_head.html' -%}
+{% include '_tail.html' -%}