Initial commit: Flask app translating Discourse User API Key flow

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-03-04 14:53:29 +01:00 · 2026-03-04 14:53:29 +01:00 · d8f5a7f77c
commit d8f5a7f77c
7 changed files with 124 additions and 0 deletions
--- a/.gitignore
+++ b/.gitignore
@ -0,0 +1 @@
+config.yaml
--- a/12
+++ b/12
@ -0,0 +1,12 @@
+FROM python:3.12-slim
+
+WORKDIR /app
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY . .
+
+EXPOSE 8000
+
+CMD ["python", "app.py", "/config/config.yaml"]
--- a/app.py
+++ b/app.py
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+import argparse
+import base64
+import json
+import secrets
+
+import yaml
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import padding, rsa
+from flask import Flask, redirect, render_template, request, session, url_for
+
+parser = argparse.ArgumentParser()
+parser.add_argument("config", help="Path to configuration file")
+args = parser.parse_args()
+
+with open(args.config) as f:
+    config = yaml.safe_load(f)
+
+app = Flask(__name__)
+app.secret_key = config["secret_key"]
+
+private_key = rsa.generate_private_key(public_exponent=65537, key_size=2048)
+
+
+@app.route("/")
+def index():
+    return render_template("index.html", application_name=config["application_name"])
+
+
+@app.route("/authorize")
+def authorize():
+    public_key = private_key.public_key().public_bytes(
+        serialization.Encoding.PEM,
+        serialization.PublicFormat.SubjectPublicKeyInfo,
+    ).decode()
+
+    nonce = secrets.token_hex(16)
+    client_id = secrets.token_hex(48)
+    session["nonce"] = nonce
+    session["client_id"] = client_id
+
+    params = {
+        "auth_redirect": config["redirect_url"],
+        "application_name": config["application_name"],
+        "scopes": "read",
+        "client_id": client_id,
+        "nonce": nonce,
+        "public_key": public_key,
+    }
+    query = "&".join(f"{k}={v}" for k, v in params.items())
+    return redirect(f"{config['forum_url']}/user-api-key/new?{query}")
+
+
+@app.route("/callback")
+def callback():
+    payload_b64 = request.args.get("payload")
+    if not payload_b64:
+        return "Missing payload", 400
+
+    try:
+        payload = base64.b64decode(payload_b64)
+        data = private_key.decrypt(payload, padding.PKCS1v15())
+        response = json.loads(data)
+    except Exception:
+        return "Failed to decrypt or decode payload", 400
+
+    if response.get("nonce") != session.get("nonce"):
+        return "Invalid nonce", 400
+
+    key = response["key"]
+    calendar_url = f"{config['forum_url']}/discourse-post-event/events.ics?order=desc&api_key={key}"
+
+    return render_template(
+        "result.html",
+        application_name=config["application_name"],
+        calendar_url=calendar_url,
+    )
+
+
+if __name__ == "__main__":
+    app.run(host="0.0.0.0", port=8000)
--- a/config.example.yaml
+++ b/config.example.yaml
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+forum_url: "https://forum.example.com"
+redirect_url: "https://myapp.example.com/callback"
+application_name: "My Calendar App"
+secret_key: "change-me-to-a-long-random-string"
--- a/requirements.txt
+++ b/requirements.txt
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+flask
+cryptography
+pyyaml
--- a/templates/index.html
+++ b/templates/index.html
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+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <title>{{ application_name }}</title>
+</head>
+<body>
+  <h1>{{ application_name }}</h1>
+  <p>Click the button below to authorize access and generate your personal calendar link.</p>
+  <a href="{{ url_for('authorize') }}"><button>Generate Calendar Link</button></a>
+</body>
+</html>
--- a/templates/result.html
+++ b/templates/result.html
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+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <title>{{ application_name }}</title>
+</head>
+<body>
+  <h1>{{ application_name }}</h1>
+  <p>Your calendar URL &mdash; save it, it won't be displayed again:</p>
+  <pre><a href="{{ calendar_url }}">{{ calendar_url }}</a></pre>
+</body>
+</html>