wip: Google login

local_dev.sh

@@ -1,3 +1,3 @@
 export FLASK_APP=yt_pubsub_handler
 export FLASK_ENV=development
-flask run
+flask run --cert=adhoc

requirements.txt

@@ -4,11 +4,14 @@ attrs==20.3.0
 boto3==1.17.84
 botocore==1.20.84
 certifi==2020.12.5
+cffi==1.14.6
 cfn-flip==1.2.3
 chardet==4.0.0
 click==7.1.2
+cryptography==3.4.7
 durationpy==0.5
 Flask==1.1.2
+Flask-Login==0.5.0
 Flask-Migrate==3.0.1
 flask-ngrok==0.0.25
 Flask-SQLAlchemy==2.5.1
@@ -25,6 +28,7 @@ kappa==0.6.0
 Mako==1.1.4
 MarkupSafe==1.1.1
 mysql-connector-python==8.0.25
+oauthlib==3.1.1
 packaging==20.9
 pep517==0.10.0
 pip-tools==6.1.0
@@ -36,6 +40,8 @@ protobuf==3.17.3
 psycopg2-binary==2.8.6
 py==1.10.0
 pycodestyle==2.7.0
+pycparser==2.20
+pyOpenSSL==20.0.1
 pyparsing==2.4.7
 pytest==6.2.3
 python-dateutil==2.8.1

yt_pubsub_handler/__init__.py

@@ -1,10 +1,31 @@
 import os
 
 from flask import Flask, render_template
+from flask_login import (
+    LoginManager,
+    current_user
+)
+from oauthlib.oauth2 import WebApplicationClient
+
 from . import models
 
+# Configuration
+GOOGLE_CLIENT_ID = os.environ.get("GOOGLE_CLIENT_ID", None)
+GOOGLE_CLIENT_SECRET = os.environ.get("GOOGLE_CLIENT_SECRET", None)
+GOOGLE_DISCOVERY_URL = (
+    "https://accounts.google.com/.well-known/openid-configuration"
+)
 
 db = models.db
+login_manager = LoginManager()
+client = WebApplicationClient(GOOGLE_CLIENT_ID)
+
+
+# Flask-Login helper to retrieve a user from our db
+@login_manager.user_loader
+def load_user(user_id):
+    from .user import User
+    return User.get(user_id)
 
 
 def create_app(test_config=None):
@@ -30,7 +51,7 @@ def create_app(test_config=None):
 
     @app.route("/")
     def index():
-        return render_template("index.html")
+        return render_template("index.html", current_user=current_user)
 
 
     @app.route("/renew_leases")
@@ -43,13 +64,22 @@ def renew_lease():
     db.app = app
     db.init_app(app)
     # sets up flask init-db cmd
+    # create a local sqlite db if in dev mode
     from . import db_utils
+    if os.getenv("FLASK_ENV") == "development":
+        db_utils.init_db()
     db_utils.init_app(app)
 
     from . import pubsubhub
     app.register_blueprint(pubsubhub.bp)
     from . import subscriptions
     app.register_blueprint(subscriptions.bp)
+    from . import auth
+    app.register_blueprint(auth.bp)
     from flask_migrate import Migrate
     migrate = Migrate(app, db)
+
+    # user session management setup
+    login_manager.init_app(app)
+
     return app

yt_pubsub_handler/auth.py

@@ -0,0 +1,90 @@
+from enum import unique
+import json
+from flask_login.utils import login_required
+
+import requests
+from flask import Blueprint, request, current_app, render_template, url_for, redirect
+from flask_login import login_user, login_required, logout_user
+
+from yt_pubsub_handler import GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET, GOOGLE_DISCOVERY_URL, client
+from . import models
+from .user import User
+
+bp = Blueprint("auth", __name__, url_prefix="/auth")
+
+
+def get_google_provider_cfg():
+    # TODO: make this more resilient
+    return requests.get(GOOGLE_DISCOVERY_URL, timeout=60).json()
+
+
+@bp.route("/login")
+def login():
+    # find out which URL to hit for Google login
+    google_provider_cfg = get_google_provider_cfg()
+    auth_endpoint = google_provider_cfg["authorization_endpoint"]
+
+    # Use library to construc tht request for Google login
+    # and provide scopes that let you retrieve user's profile from Google
+    request_uri = client.prepare_request_uri(
+        auth_endpoint,
+        redirect_uri=request.url_root + "auth/login/callback",
+        scope=["openid", "email"]
+    )
+    return redirect(request_uri)
+
+
+@bp.route("/login/callback")
+def callback():
+    # Get authorization code Google sends back
+    code = request.args.get("code")
+
+    google_provider_cfg = get_google_provider_cfg()
+    token_endpoint = google_provider_cfg["token_endpoint"]
+
+    token_url, headers, body = client.prepare_token_request(
+        token_endpoint,
+        authorization_response=request.url,
+        redirect_url=request.base_url,
+        code=code
+    )
+
+    token_response = requests.post(
+        token_url,
+        headers=headers,
+        data=body,
+        auth=(GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET)
+    )
+
+    # parse the tokens
+    client.parse_request_body_response(json.dumps(token_response.json()))
+    # get user info
+    userinfo_endpoint = google_provider_cfg["userinfo_endpoint"]
+    uri, headers, body = client.add_token(userinfo_endpoint)
+    userinfo_response = requests.get(uri, headers=headers, data=body)
+
+    # ensure that email is verified
+    if userinfo_response.json().get("email_verified"):
+        unique_id = userinfo_response.json()["sub"]
+        users_email = userinfo_response.json()["email"]
+    else:
+        return "User email not available or not verified by Google.", 400
+
+    # create a user in the db
+    user = User(
+        id_=unique_id,
+        email=users_email
+    )
+
+    if not User.get(unique_id):
+        User.create(unique_id, users_email)
+
+    login_user(user)
+    return redirect(url_for("index"))
+
+
+@bp.route("/logout")
+@login_required
+def logout():
+    logout_user()
+    return redirect(url_for("index"))

yt_pubsub_handler/models.py

@@ -35,3 +35,11 @@ class Subscription(db.Model):
 
     def __repr__(self):
         return f"Subscription {self.id} {self.channel_id} {self.subreddit}>"
+
+
+class User(db.Model):
+    id = db.Column(db.String(), primary_key=True)
+    email = db.Column(db.String(), unique=True, nullable=False)
+
+    def __repr__(self):
+        return f"User {self.id} {self.email}>"

yt_pubsub_handler/user.py

@@ -0,0 +1,29 @@
+from flask_login import UserMixin
+from yt_pubsub_handler import db
+from . import models
+
+
+class User(UserMixin):
+    def __init__(self, id_, email):
+        self.id = id_
+        self.email = email
+
+    @staticmethod
+    def get(user_id):
+        user = models.User.query.filter_by(id=user_id).first()
+        if not user:
+            return None
+        user = User(
+            id_=user.id,
+            email=user.email
+        )
+        return user
+
+    @staticmethod
+    def create(id_, email):
+        new_user = models.User(
+            id=str(id_),
+            email=email
+        )
+        db.session.add(new_user)
+        db.session.commit()