Add persistent PostgreSQL stack and SQLite migration

TelcoPortal-source/app.py

@@ -4,7 +4,7 @@ from datetime import date, datetime, timedelta
 from functools import wraps
 
 from flask import Flask, jsonify, redirect, render_template, request, session, url_for
-from sqlalchemy import text
+from sqlalchemy import URL, inspect, text
 from werkzeug.security import check_password_hash, generate_password_hash
 
 from models import InternetConnection, Phone, User, db
@@ -59,7 +59,7 @@ def get_or_create_secret_key():
 
 def create_app():
     app = Flask(__name__)
-    app.config["SQLALCHEMY_DATABASE_URI"] = f"sqlite:///{DB_PATH}"
+    app.config["SQLALCHEMY_DATABASE_URI"] = get_database_uri()
     app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
     app.config["JSON_SORT_KEYS"] = False
     app.config["PERMANENT_SESSION_LIFETIME"] = timedelta(days=30)
@@ -79,7 +79,7 @@ def create_app():
 def run_migrations():
     """Lightweight in-place migrations for columns added after the DB was first created.
     db.create_all() only creates missing tables, not missing columns on existing tables."""
-    existing_columns = {row[1] for row in db.session.execute(text("PRAGMA table_info(phones)")).fetchall()}
+    existing_columns = {column["name"] for column in inspect(db.engine).get_columns("phones")}
     if "comment" not in existing_columns:
         db.session.execute(text("ALTER TABLE phones ADD COLUMN comment TEXT"))
         db.session.commit()
@@ -88,6 +88,26 @@ def run_migrations():
         db.session.commit()
 
 
+def get_database_uri():
+    """Use the Docker database service when configured, with SQLite as a local-dev fallback."""
+    database_url = os.environ.get("DATABASE_URL")
+    if database_url:
+        return database_url
+
+    database_host = os.environ.get("TELCO_DB_HOST")
+    if database_host:
+        return URL.create(
+            drivername="postgresql+psycopg2",
+            username=os.environ.get("TELCO_DB_USER", "telco"),
+            password=os.environ.get("TELCO_DB_PASSWORD", "telco"),
+            host=database_host,
+            port=int(os.environ.get("TELCO_DB_PORT", "5432")),
+            database=os.environ.get("TELCO_DB_NAME", "telco"),
+        )
+
+    return f"sqlite:///{DB_PATH}"
+
+
 def seed_users():
     """First-run only: create the initial login accounts if no users exist yet at all."""
     if User.query.count() > 0: