Server README

Backend service for a static website. The app accepts contact and newsletter submissions, persists them, applies rate limiting and origin checks, and sends notification emails when SMTP is configured. Includes admin authentication for accessing application settings and managing dynamic configuration.

Table of Contents

• Server README
  • Table of Contents
  • Overview
  • Architecture
  • Quick Start
    • Admin Access
  • API Surface
  • Embeddable Forms
  • Running With Docker
    • Build manually
    • Run with explicit environment variables
    • Run using docker-compose
  • Environment Variables
    • Core runtime
    • Admin authentication
    • Database configuration
    • Email delivery
    • Rate limiting and caching
    • Request hardening
    • Observability
    • Docker / Gunicorn runtime
  • Health Checks and Monitoring
  • Testing
  • Deployment Notes
  • Email Templates

Overview

• Flask application exposed through app.py (development) and Gunicorn (container runtime)
• Service and blueprint architecture under server/ for HTTP routes, business logic, and observability
• SQLite by default with optional PostgreSQL support and Redis-backed distributed rate limiting
• Docker- and docker-compose-friendly with health checks and environment-driven configuration

Architecture

• app.py: simple shim that imports the Flask app for local development.
• server/: application package.
  • factory.py: application factory that wires logging, middleware, routes, and database initialisation.
  • routes/: Flask blueprints for contact, newsletter, monitoring, auth, and admin endpoints.
  • services/: reusable business logic for persisting submissions and sending notifications.
  • database.py: SQLite/PostgreSQL helpers and connection management.
  • middleware.py, rate_limit.py, metrics.py: request guards, throttling, and Prometheus-style instrumentation.
  • settings.py: environment-driven configuration loader.
  • auth.py: authentication utilities and login required decorator.
• templates/: Jinja2 templates for HTML pages (login, admin dashboard, newsletter management, settings).
• entrypoint.sh: container entrypoint that tunes Gunicorn worker count and timeout before booting the WSGI app.
• Dockerfile: multi-stage build that installs requirements in a builder image and runs the app behind Gunicorn.
• docker-compose.yml: local stack for the API with bind-mounted SQLite data.
• docker-compose.redis.yml: optional Redis sidecar for distributed rate limiting tests.
• tests/: pytest suite covering API behaviour, services, metrics, and SMTP integration (opt-in).

Quick Start

1. Create a virtual environment and install dependencies:

   python -m venv .venv
   .\.venv\Scripts\Activate.ps1
   pip install -r requirements.txt
   

2. Copy the sample environment file and adjust values:

   Copy-Item .env.example .env
   

3. Run the development server:

   python app.py
   

The development server listens on http://127.0.0.1:5002 by default.

Admin Access

Access the admin interface at http://127.0.0.1:5002/auth/login using the configured ADMIN_USERNAME and ADMIN_PASSWORD (defaults: admin/admin). The admin interface provides a dashboard overview, newsletter subscriber management with search and pagination, newsletter creation and sending capabilities, and dynamic application settings management. The settings page displays current application configuration and allows dynamic management of application settings, while the submissions page allows viewing and managing contact form submissions.

API Surface

• POST /api/contact: accepts name, email, message, and optional company, timeline.
• GET /api/contact: retrieves contact form submissions (admin only, requires authentication). Supports pagination (page, per_page), filtering (email, date_from, date_to), and sorting (sort_by, sort_order).
• GET /api/contact/<id>: retrieves a specific contact submission by ID (admin only).
• DELETE /api/contact/<id>: deletes a contact submission by ID (admin only).
• POST /api/newsletter: subscribes an address and optional metadata to the newsletter list. Sends a confirmation email if SMTP is configured.
• DELETE /api/newsletter: unsubscribes an email address from the newsletter list.
• PUT /api/newsletter: updates a subscriber's email address (requires old_email and new_email).
• GET /api/newsletter/manage: displays HTML form for newsletter subscription management.
• POST /api/newsletter/manage: processes subscription management actions (subscribe, unsubscribe, update).
• GET /newsletter/unsubscribe/confirmation: displays unsubscription confirmation page.
• GET /health: lightweight database connectivity check used for container health monitoring.
• GET /metrics: Prometheus-compatible metrics endpoint (requires ENABLE_REQUEST_LOGS for detailed tracing).
• GET /admin/api/settings: retrieves all application settings (admin only).
• PUT /admin/api/settings/<key>: updates a specific application setting (admin only).
• DELETE /admin/api/settings/<key>: deletes a specific application setting (admin only).
• GET /admin/api/newsletter: retrieves newsletter subscribers with pagination, filtering, and sorting (admin only).
• POST /admin/api/newsletters: creates a new newsletter (admin only).
• GET /admin/api/newsletters: retrieves newsletters with pagination and filtering (admin only).
• POST /admin/api/newsletters/<id>/send: sends a newsletter to all subscribers (admin only).
• GET /admin/api/contact: retrieves contact form submissions with pagination, filtering, and sorting (admin only).
• DELETE /admin/api/contact/<id>: deletes a contact submission by ID (admin only).
• GET /embed/contact: serves an HTML page with a contact form that can be embedded in an iframe on external sites.
• GET /embed/newsletter: serves an HTML page with a newsletter subscription form that can be embedded in an iframe on external sites.

Embeddable Forms

The application provides embeddable contact and newsletter subscription forms that can be integrated into other websites via iframe. CORS (Cross-Origin Resource Sharing) headers are automatically added to API endpoints to allow forms embedded on external sites to submit data successfully.

• GET /embed/contact: serves an HTML page with a contact form that can be embedded in an iframe on external sites.
• GET /embed/newsletter: serves an HTML page with a newsletter subscription form that can be embedded in an iframe on external sites.

To embed the contact form on another website, use the following HTML code:

<iframe
  src="https://your-server-domain/embed/contact"
  width="600"
  height="400"
  frameborder="0"
  allowfullscreen
></iframe>

To embed the newsletter subscription form:

<iframe
  src="https://your-server-domain/embed/newsletter"
  width="600"
  height="300"
  frameborder="0"
  allowfullscreen
></iframe>

Replace https://your-server-domain with your actual server URL. The iframe codes are available in the admin settings page for easy copying.

Running With Docker

Build manually

docker build -t backend-server -f Dockerfile .

Run with explicit environment variables

docker run --rm -p 5002:5002 `
  -e FLASK_SECRET_KEY=change-me `
  -e SMTP_HOST=smtp.example.com `
  -e SMTP_PORT=587 `
  -e SMTP_USERNAME=api@example.com `
  -e SMTP_PASSWORD=secret `
  -e SMTP_RECIPIENTS=hello@example.com `
  backend-server

Run using docker-compose

docker-compose up --build

• Mounts ./data into the container for SQLite persistence.
• Exposes port 5002 and wires environment variables from your .env file.

To experiment with Redis-backed throttling:

docker-compose -f docker-compose.redis.yml up --build

Environment Variables

See .env.example for a complete reference. The most relevant groups are captured below.

Core runtime

Variable	Description	Default
FLASK_SECRET_KEY	Secret used by Flask for session signing; set to a strong random value in production.	dev
ENABLE_JSON_LOGS	Emit logs in JSON format when true.	false
ENABLE_REQUEST_LOGS	Enable request start/end logging.	true

Admin authentication

Variable	Description	Default
ADMIN_USERNAME	Username for admin login.	admin
ADMIN_PASSWORD	Password for admin login.	admin

Database configuration

Variable	Description	Default
DATABASE_URL	SQLite URL or filesystem path. Examples: sqlite:///./forms.db, ./data/forms.db.	sqlite:///./data/forms.db
POSTGRES_URL	PostgreSQL connection URI, e.g. postgresql://user:pass@host:5432/dbname. Requires psycopg2-binary installed.	(none)

When POSTGRES_URL is set and psycopg2-binary is available, the app prefers PostgreSQL. Otherwise it falls back to SQLite. A custom DATABASE_URL always wins over POSTGRES_URL to simplify local development.

Email delivery

Variable	Description	Default
SMTP_HOST	SMTP server hostname or IP. Leave empty to disable email notifications.	(none)
SMTP_PORT	SMTP server port.	587
SMTP_USERNAME	Username for SMTP authentication.	(none)
SMTP_PASSWORD	Password or token for SMTP authentication.	(none)
SMTP_SENDER	Sender email address; defaults to SMTP_USERNAME when unset.	(none)
SMTP_RECIPIENTS	Comma-separated recipient list for notifications.	(none)
SMTP_USE_TLS	Enables STARTTLS when true.	true

Rate limiting and caching

Variable	Description	Default
RATE_LIMIT_MAX	Maximum submissions allowed per window from a single IP. Set to 0 to disable throttling.	10
RATE_LIMIT_WINDOW	Sliding window size (seconds) for rate limiting.	60
REDIS_URL	Redis connection string for distributed rate limiting; when empty, use in-memory storage.	(none)

Request hardening

Variable	Description	Default
STRICT_ORIGIN_CHECK	Enforce Origin/Referer validation when true.	false
ALLOWED_ORIGIN	Expected site origin (e.g. https://example.com) used by strict origin checks.	(none)

Observability

Variable	Description	Default
SENTRY_DSN	Sentry project DSN for error reporting.	(none)
SENTRY_TRACES_SAMPLE_RATE	Sampling rate for Sentry performance tracing (0-1).	0.0

Docker / Gunicorn runtime

Variable	Description	Default
GUNICORN_WORKERS	Overrides auto-calculated worker count; leave blank to use (2 × CPU) + 1 capped at 8 workers.	(auto)
GUNICORN_TIMEOUT	Worker timeout in seconds used by Gunicorn.	30

Health Checks and Monitoring

• /health and Docker health checks verify that the API can reach the configured database.
• /metrics surfaces request counters, latency histograms, rate limit metrics, and SMTP success/error counts.
• Enable Sentry by setting SENTRY_DSN to forward exceptions and performance traces.

Testing

pytest -q tests

SMTP integration tests are skipped unless RUN_SMTP_INTEGRATION_TEST=1 and valid SMTP credentials are set. Run pytest -q tests/test_integration_smtp.py to target them explicitly.

Deployment Notes

• A single Gitea Actions workflow (.github/workflows/ci.yml) exercises pytest on each push, pull request, or manual dispatch, then conditionally builds the Docker image.
• When the default branch (main) runs and registry secrets (REGISTRY_URL, REGISTRY_USERNAME, REGISTRY_PASSWORD) are configured in Gitea, the workflow logs in and pushes both latest and commit-specific image tags.
• Import or mirror the required reusable actions (actions/checkout, actions/setup-python, and the Docker actions) into your Gitea instance so that the workflow can resolve them.
• For production use, deploy the container behind a load balancer or reverse proxy and supply the appropriate environment variables.

Email Templates

The application supports customizable email templates for newsletter confirmations. The confirmation email template can be edited through the admin settings page under the dynamic settings management. The template uses HTML format and should include an unsubscribe link for compliance with email regulations.

Default confirmation email includes:

• Welcome message
• Unsubscribe instructions with link to /newsletter/manage
• Customizable HTML content