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StarPunk/docs/architecture/overview.md
2025-11-18 19:21:31 -07:00

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# StarPunk Architecture Overview
## Executive Summary
StarPunk is a minimal, single-user IndieWeb CMS designed around the principle: "Every line of code must justify its existence." The architecture prioritizes simplicity, standards compliance, and user data ownership through careful technology selection and hybrid data storage.
**Core Architecture**: API-first Flask application with hybrid file+database storage, server-side rendering, and delegated authentication.
## System Architecture
### High-Level Components
```
┌─────────────────────────────────────────────────────────────┐
│ User Browser │
└───────────────┬─────────────────────────────────────────────┘
│ HTTP/HTTPS
┌─────────────────────────────────────────────────────────────┐
│ Flask Application │
│ ┌─────────────────────────────────────────────────────────┤
│ │ Web Interface (Jinja2 Templates) │
│ │ - Public: Homepage, Note Permalinks │
│ │ - Admin: Dashboard, Note Editor │
│ └──────────────────────────────┬──────────────────────────┘
│ ┌──────────────────────────────┴──────────────────────────┐
│ │ API Layer (RESTful + Micropub) │
│ │ - Notes CRUD API │
│ │ - Micropub Endpoint │
│ │ - RSS Feed Generator │
│ │ - Authentication Handlers │
│ └──────────────────────────────┬──────────────────────────┘
│ ┌──────────────────────────────┴──────────────────────────┐
│ │ Business Logic │
│ │ - Note Management (create, read, update, delete) │
│ │ - File/Database Sync │
│ │ - Markdown Rendering │
│ │ - Slug Generation │
│ │ - Session Management │
│ └──────────────────────────────┬──────────────────────────┘
│ ┌──────────────────────────────┴──────────────────────────┐
│ │ Data Layer │
│ │ ┌──────────────────┐ ┌─────────────────────────┐ │
│ │ │ File Storage │ │ SQLite Database │ │
│ │ │ │ │ │ │
│ │ │ Markdown Files │ │ - Note Metadata │ │
│ │ │ (Pure Content) │ │ - Sessions │ │
│ │ │ │ │ - Tokens │ │
│ │ │ data/notes/ │ │ - Auth State │ │
│ │ │ YYYY/MM/ │ │ │ │
│ │ │ slug.md │ │ data/starpunk.db │ │
│ │ └──────────────────┘ └─────────────────────────┘ │
│ └─────────────────────────────────────────────────────────┘
└─────────────────────────────────────────────────────────────┘
│ HTTPS
┌─────────────────────────────────────────────────────────────┐
│ External Services │
│ - IndieLogin.com (Authentication) │
│ - User's Website (Identity Verification) │
│ - Micropub Clients (Publishing) │
└─────────────────────────────────────────────────────────────┘
```
## Core Principles
### 1. Radical Simplicity
- Total dependencies: 6 direct packages
- No build tools, no npm, no bundlers
- Server-side rendering eliminates frontend complexity
- Single file SQLite database
- Zero configuration frameworks
### 2. Hybrid Data Architecture
**Files for Content**: Markdown notes stored as plain text files
- Maximum portability
- Human-readable
- Direct user access
- Easy backup (copy, rsync, git)
**Database for Metadata**: SQLite stores structured data
- Fast queries and indexes
- Referential integrity
- Efficient filtering and sorting
- Transaction support
**Sync Strategy**: Files are authoritative for content; database is authoritative for metadata. Both must stay in sync.
### 3. Standards-First Design
- IndieWeb: Microformats2, IndieAuth, Micropub
- Web: HTML5, RSS 2.0, HTTP standards
- Security: OAuth 2.0, HTTPS, secure cookies
- Data: CommonMark markdown
### 4. API-First Architecture
All functionality exposed via API, web interface consumes API. This enables:
- Micropub client support
- Future client applications
- Scriptable automation
- Clean separation of concerns
### 5. Progressive Enhancement
- Core functionality works without JavaScript
- JavaScript adds optional enhancements (markdown preview)
- Server-side rendering for fast initial loads
- Mobile-responsive from the start
## Component Descriptions
### Web Layer
#### Public Interface
**Purpose**: Display published notes to the world
**Technology**: Server-side rendered HTML (Jinja2)
**Routes**:
- `/` - Homepage with recent notes
- `/note/{slug}` - Individual note permalink
- `/feed.xml` - RSS feed
**Features**:
- Microformats2 markup (h-entry, h-card)
- Reverse chronological note list
- Clean, minimal design
- Mobile-responsive
- No JavaScript required
#### Admin Interface
**Purpose**: Manage notes (create, edit, publish)
**Technology**: Server-side rendered HTML (Jinja2) + optional vanilla JS
**Routes**:
- `/admin/login` - Authentication
- `/admin` - Dashboard (list of all notes)
- `/admin/new` - Create new note
- `/admin/edit/{id}` - Edit existing note
**Features**:
- Markdown editor
- Optional real-time preview (JS enhancement)
- Publish/draft toggle
- Protected by session authentication
### API Layer
#### Notes API
**Purpose**: CRUD operations for notes
**Authentication**: Session-based (admin interface)
**Routes**:
```
GET /api/notes List published notes
POST /api/notes Create new note
GET /api/notes/{id} Get single note
PUT /api/notes/{id} Update note
DELETE /api/notes/{id} Delete note
```
**Response Format**: JSON
#### Micropub Endpoint
**Purpose**: Accept posts from external Micropub clients
**Authentication**: IndieAuth bearer tokens
**Routes**:
```
POST /api/micropub Create note (h-entry)
GET /api/micropub?q=config Query configuration
GET /api/micropub?q=source Query note source
```
**Content Types**:
- application/json
- application/x-www-form-urlencoded
**Compliance**: Full Micropub specification
#### RSS Feed
**Purpose**: Syndicate published notes
**Technology**: feedgen library
**Route**: `/feed.xml`
**Format**: Valid RSS 2.0 XML
**Caching**: 5 minutes
**Features**:
- All published notes
- RFC-822 date formatting
- CDATA-wrapped HTML content
- Proper GUID for each item
### Business Logic Layer
#### Note Management
**Operations**:
1. **Create**: Generate slug → write file → insert database record
2. **Read**: Query database for path → read file → render markdown
3. **Update**: Write file atomically → update database timestamp
4. **Delete**: Mark deleted in database → optionally archive file
**Key Components**:
- Slug generation (URL-safe, unique)
- Markdown rendering (markdown library)
- Content hashing (integrity verification)
- Atomic file operations (prevent corruption)
#### File/Database Sync
**Strategy**: Write files first, then database
**Rollback**: If database operation fails, delete/restore file
**Verification**: Content hash detects external modifications
**Integrity Check**: Optional scan for orphaned files/records
#### Authentication
**Admin Auth**: IndieLogin.com OAuth 2.0 flow
- User enters website URL
- Redirect to indielogin.com
- Verify identity via RelMeAuth or email
- Return verified "me" URL
- Create session token
- Store in HttpOnly cookie
**Micropub Auth**: IndieAuth token verification
- Client obtains token via IndieAuth flow
- Token sent as Bearer in Authorization header
- Verify token exists and not expired
- Check scope permissions
### Data Layer
#### File Storage
**Location**: `data/notes/`
**Structure**: `YYYY/MM/slug.md`
**Format**: Pure markdown, no frontmatter
**Operations**:
- Atomic writes (temp file → rename)
- Directory creation (makedirs)
- Content reading (UTF-8 encoding)
**Example**:
```
data/notes/
├── 2024/
│ ├── 11/
│ │ ├── my-first-note.md
│ │ └── another-note.md
│ └── 12/
│ └── december-note.md
```
#### Database Storage
**Location**: `data/starpunk.db`
**Engine**: SQLite3
**Tables**:
- `notes` - Metadata (slug, file_path, published, timestamps, hash)
- `sessions` - Auth sessions (token, me, expiry)
- `tokens` - Micropub tokens (token, me, client_id, scope)
- `auth_state` - CSRF tokens (state, expiry)
**Indexes**:
- `notes.created_at` (DESC) - Fast chronological queries
- `notes.published` - Fast filtering
- `notes.slug` - Fast lookup by slug
- `sessions.session_token` - Fast auth checks
**Queries**: Direct SQL using Python sqlite3 module (no ORM)
## Data Flow Examples
### Creating a Note (via Admin Interface)
```
1. User fills out form at /admin/new
2. POST to /api/notes with markdown content
3. Verify user session (check session cookie)
4. Generate unique slug from content or timestamp
5. Determine file path: data/notes/2024/11/slug.md
6. Create directories if needed (makedirs)
7. Write markdown content to file (atomic write)
8. Calculate SHA-256 hash of content
9. Begin database transaction
10. Insert record into notes table:
- slug
- file_path
- published (from form)
- created_at (now)
- updated_at (now)
- content_hash
11. If database insert fails:
- Delete file
- Return error to user
12. If database insert succeeds:
- Commit transaction
- Return success with note URL
13. Redirect user to /admin (dashboard)
```
### Reading a Note (via Public Interface)
```
1. User visits /note/my-first-note
2. Extract slug from URL
3. Query database:
SELECT file_path, created_at, published
FROM notes
WHERE slug = 'my-first-note' AND published = 1
4. If not found → 404 error
5. Read markdown content from file:
- Open data/notes/2024/11/my-first-note.md
- Read UTF-8 content
6. Render markdown to HTML (markdown.markdown())
7. Render Jinja2 template with:
- content_html (rendered HTML)
- created_at (timestamp)
- slug (for permalink)
8. Return HTML with microformats markup
```
### Publishing via Micropub
```
1. Micropub client POSTs to /api/micropub
Headers: Authorization: Bearer {token}
Body: {"type": ["h-entry"], "properties": {"content": ["..."]}}
2. Extract bearer token from Authorization header
3. Query database:
SELECT me, scope FROM tokens
WHERE token = {token} AND expires_at > now()
4. If token invalid → 401 Unauthorized
5. Parse Micropub JSON payload
6. Extract content from properties.content[0]
7. Create note (same flow as admin interface):
- Generate slug
- Write file
- Insert database record
8. If successful:
- Return 201 Created
- Set Location header to note URL
9. Client receives note URL, displays success
```
### IndieLogin Authentication Flow
```
1. User visits /admin/login
2. User enters their website: https://alice.example.com
3. POST to /admin/login with "me" parameter
4. Validate URL format
5. Generate random state token (CSRF protection)
6. Store state in database with 5-minute expiry
7. Build IndieLogin authorization URL:
https://indielogin.com/auth?
me=https://alice.example.com
client_id=https://starpunk.example.com
redirect_uri=https://starpunk.example.com/auth/callback
state={random_state}
8. Redirect user to IndieLogin
9. IndieLogin verifies user's identity:
- Checks rel="me" links on alice.example.com
- Or sends email verification
- User authenticates via chosen method
10. IndieLogin redirects back:
/auth/callback?code={auth_code}&state={state}
11. Verify state matches stored value (CSRF check)
12. Exchange code for verified identity:
POST https://indielogin.com/auth
code={auth_code}
client_id=https://starpunk.example.com
redirect_uri=https://starpunk.example.com/auth/callback
13. IndieLogin returns: {"me": "https://alice.example.com"}
14. Verify me == ADMIN_ME (config)
15. If match:
- Generate session token
- Insert into sessions table
- Set HttpOnly, Secure cookie
- Redirect to /admin
16. If no match:
- Return "Unauthorized" error
- Log attempt
```
## Security Architecture
### Authentication Security
#### Session Management
- **Token Generation**: `secrets.token_urlsafe(32)` (256-bit entropy)
- **Storage**: Hash before storing in database
- **Cookies**: HttpOnly, Secure, SameSite=Lax
- **Expiry**: 30 days, extendable on use
- **Validation**: Every protected route checks session
#### CSRF Protection
- **State Tokens**: Random tokens for OAuth flows
- **Expiry**: 5 minutes (short-lived)
- **Single-Use**: Deleted after verification
- **SameSite**: Cookies set to Lax mode
#### Access Control
- **Admin Routes**: Require valid session
- **Micropub Routes**: Require valid bearer token
- **Public Routes**: No authentication needed
- **Identity Verification**: Only ADMIN_ME can authenticate
### Input Validation
#### User Input
- **Markdown**: Sanitize to prevent XSS in rendered HTML
- **URLs**: Validate format and scheme (https://)
- **Slugs**: Alphanumeric + hyphens only
- **JSON**: Parse and validate structure
- **File Paths**: Prevent directory traversal (validate against base path)
#### Micropub Payloads
- **Content-Type**: Verify matches expected format
- **Required Fields**: Validate h-entry structure
- **Size Limits**: Prevent DoS via large payloads
- **Scope Verification**: Check token has required permissions
### Database Security
#### SQL Injection Prevention
- **Parameterized Queries**: Always use parameter substitution
- **No String Interpolation**: Never build SQL with f-strings
- **Input Sanitization**: Validate before database operations
Example:
```python
# GOOD
cursor.execute("SELECT * FROM notes WHERE slug = ?", (slug,))
# BAD (SQL injection vulnerable)
cursor.execute(f"SELECT * FROM notes WHERE slug = '{slug}'")
```
#### Data Integrity
- **Transactions**: Use for multi-step operations
- **Constraints**: UNIQUE on slugs, file_paths
- **Foreign Keys**: Enforce relationships (if applicable)
- **Content Hashing**: Detect unauthorized file modifications
### Network Security
#### HTTPS
- **Production Requirement**: TLS 1.2+ required
- **Reverse Proxy**: Nginx/Caddy handles SSL termination
- **Certificate Validation**: Verify SSL certs on outbound requests
- **HSTS**: Set Strict-Transport-Security header
#### Security Headers
```python
# Set on all responses
Content-Security-Policy: default-src 'self'
X-Frame-Options: DENY
X-Content-Type-Options: nosniff
Referrer-Policy: strict-origin-when-cross-origin
```
#### Rate Limiting
- **Implementation**: Reverse proxy (nginx/Caddy)
- **Admin Routes**: Stricter limits
- **API Routes**: Moderate limits
- **Public Routes**: Permissive limits
### File System Security
#### Atomic Operations
```python
# Write to temp file, then atomic rename
temp_path = f"{target_path}.tmp"
with open(temp_path, 'w') as f:
f.write(content)
os.rename(temp_path, target_path) # Atomic on POSIX
```
#### Path Validation
```python
# Prevent directory traversal
base_path = os.path.abspath(DATA_PATH)
requested_path = os.path.abspath(os.path.join(base_path, user_input))
if not requested_path.startswith(base_path):
raise SecurityError("Path traversal detected")
```
#### File Permissions
- **Data Directory**: 700 (owner only)
- **Database File**: 600 (owner read/write)
- **Note Files**: 600 (owner read/write)
- **Application User**: Dedicated non-root user
## Performance Considerations
### Response Time Targets
- **API Responses**: < 100ms (database + file read)
- **Page Renders**: < 200ms (template rendering)
- **RSS Feed**: < 300ms (query + file reads + XML generation)
### Optimization Strategies
#### Database
- **Indexes**: On frequently queried columns (created_at, slug, published)
- **Connection Pooling**: Single connection (single-user, no contention)
- **Query Optimization**: SELECT only needed columns
- **Prepared Statements**: Reuse compiled queries
#### File System
- **Caching**: Consider caching rendered HTML in memory (optional)
- **Directory Structure**: Year/Month prevents large directories
- **Atomic Reads**: Fast sequential reads, no locking needed
#### HTTP
- **Static Assets**: Cache headers on CSS/JS (1 year)
- **RSS Feed**: Cache for 5 minutes (Cache-Control)
- **Compression**: gzip/brotli via reverse proxy
- **ETags**: For conditional requests
#### Rendering
- **Template Compilation**: Jinja2 compiles templates automatically
- **Minimal Templating**: Simple templates render fast
- **Server-Side**: No client-side rendering overhead
### Resource Usage
#### Memory
- **Flask Process**: ~50MB base
- **SQLite**: ~10MB typical working set
- **Total**: < 100MB under normal load
#### Disk
- **Application**: ~5MB (code + dependencies)
- **Database**: ~1MB per 1000 notes
- **Notes**: ~5KB average per markdown file
- **Total**: Scales linearly with note count
#### CPU
- **Idle**: Near zero
- **Request Handling**: Minimal (no heavy processing)
- **Markdown Rendering**: Fast (pure Python)
- **Database Queries**: Indexed, sub-millisecond
## Deployment Architecture
### Single-Server Deployment
```
┌─────────────────────────────────────────────────┐
│ Internet │
└────────────────┬────────────────────────────────┘
│ Port 443 (HTTPS)
┌─────────────────────────────────────────────────┐
│ Nginx/Caddy (Reverse Proxy) │
│ - SSL/TLS termination │
│ - Static file serving │
│ - Rate limiting │
│ - Compression │
└────────────────┬────────────────────────────────┘
│ Port 8000 (HTTP)
┌─────────────────────────────────────────────────┐
│ Gunicorn (WSGI Server) │
│ - 4 worker processes │
│ - Process management │
│ - Load balancing (round-robin) │
└────────────────┬────────────────────────────────┘
│ WSGI
┌─────────────────────────────────────────────────┐
│ Flask Application │
│ - Request handling │
│ - Business logic │
│ - Template rendering │
└────────────────┬────────────────────────────────┘
┌────────────────────────────┬────────────────────┐
│ File System │ SQLite Database │
│ data/notes/ │ data/starpunk.db │
│ YYYY/MM/slug.md │ │
└────────────────────────────┴────────────────────┘
```
### Process Management (systemd)
```ini
[Unit]
Description=StarPunk CMS
After=network.target
[Service]
Type=notify
User=starpunk
WorkingDirectory=/opt/starpunk
Environment="PATH=/opt/starpunk/venv/bin"
ExecStart=/opt/starpunk/venv/bin/gunicorn -w 4 -b 127.0.0.1:8000 app:app
Restart=always
RestartSec=10
[Install]
WantedBy=multi-user.target
```
### Backup Strategy
#### Automated Daily Backup
```bash
#!/bin/bash
# backup.sh - Run daily via cron
DATE=$(date +%Y%m%d)
BACKUP_DIR="/backup/starpunk"
# Backup data directory (notes + database)
rsync -av /opt/starpunk/data/ "$BACKUP_DIR/$DATE/"
# Keep last 30 days
find "$BACKUP_DIR" -maxdepth 1 -type d -mtime +30 -exec rm -rf {} \;
```
#### Manual Backup
```bash
# Simple copy
cp -r /opt/starpunk/data /backup/starpunk-$(date +%Y%m%d)
# Or with compression
tar -czf starpunk-backup-$(date +%Y%m%d).tar.gz /opt/starpunk/data
```
### Restore Process
1. Stop application: `sudo systemctl stop starpunk`
2. Restore data directory: `rsync -av /backup/starpunk/20241118/ /opt/starpunk/data/`
3. Fix permissions: `chown -R starpunk:starpunk /opt/starpunk/data`
4. Start application: `sudo systemctl start starpunk`
5. Verify: Visit site, check recent notes
## Testing Strategy
### Test Pyramid
```
┌─────────────┐
/ \
/ Manual Tests \ Validation, Real Services
/───────────────── \
/ \
/ Integration Tests \ API Flows, Database + Files
/─────────────────────── \
/ \
/ Unit Tests \ Functions, Logic, Parsing
/───────────────────────────────\
```
### Unit Tests (pytest)
**Coverage**: Business logic, utilities, models
**Examples**:
- Slug generation and uniqueness
- Markdown rendering with various inputs
- Content hash calculation
- File path validation
- Token generation and verification
- Date formatting for RSS
- Micropub payload parsing
### Integration Tests
**Coverage**: Component interactions, full flows
**Examples**:
- Create note: file write + database insert
- Read note: database query + file read
- IndieLogin flow with mocked API
- Micropub creation with token validation
- RSS feed generation with multiple notes
- Session authentication on protected routes
### End-to-End Tests
**Coverage**: Full user workflows
**Examples**:
- Admin login via IndieLogin (mocked)
- Create note via web interface
- Publish note via Micropub client (mocked)
- View note on public site
- Verify RSS feed includes note
### Validation Tests
**Coverage**: Standards compliance
**Tools**:
- W3C HTML Validator (validate templates)
- W3C Feed Validator (validate RSS output)
- IndieWebify.me (verify microformats)
- Micropub.rocks (test Micropub compliance)
### Manual Tests
**Coverage**: Real-world usage
**Examples**:
- Authenticate with real indielogin.com
- Publish from actual Micropub client (Quill, Indigenous)
- Subscribe to feed in actual RSS reader
- Browser compatibility (Chrome, Firefox, Safari, mobile)
- Accessibility with screen reader
## Monitoring and Observability
### Logging Strategy
#### Application Logs
```python
# Structured logging
import logging
logger = logging.getLogger(__name__)
# Info: Normal operations
logger.info("Note created", extra={
"slug": slug,
"published": published,
"user": session.me
})
# Warning: Recoverable issues
logger.warning("State token expired", extra={
"state": state,
"age": age_seconds
})
# Error: Failed operations
logger.error("File write failed", extra={
"path": file_path,
"error": str(e)
})
```
#### Log Levels
- **DEBUG**: Development only (verbose)
- **INFO**: Normal operations (note creation, auth success)
- **WARNING**: Unusual but handled (expired tokens, invalid input)
- **ERROR**: Failed operations (file I/O errors, database errors)
- **CRITICAL**: System failures (database unreachable)
#### Log Destinations
- **Development**: Console (stdout)
- **Production**: File rotation (logrotate) + optional syslog
### Metrics (Optional for V2)
**Simple Metrics** (if desired):
- Note count (query database)
- Request count (nginx logs)
- Error rate (grep application logs)
- Response times (nginx logs)
**Advanced Metrics** (V2):
- Prometheus exporter
- Grafana dashboard
- Alert on error rate spike
### Health Checks
```python
@app.route('/health')
def health_check():
"""Simple health check for monitoring"""
try:
# Check database
db.execute("SELECT 1").fetchone()
# Check file system
os.path.exists(DATA_PATH)
return {"status": "ok"}, 200
except Exception as e:
return {"status": "error", "detail": str(e)}, 500
```
## Migration and Evolution
### V1 to V2 Migration
#### Database Schema Changes
```sql
-- Add new column with default
ALTER TABLE notes ADD COLUMN tags TEXT DEFAULT '';
-- Create new table
CREATE TABLE tags (
id INTEGER PRIMARY KEY,
name TEXT UNIQUE NOT NULL
);
-- Migration script updates existing notes
```
#### File Format Evolution
**V1**: Pure markdown
**V2** (if needed): Add optional frontmatter
```markdown
---
tags: indieweb, cms
---
Note content here
```
**Backward Compatibility**: Parser checks for frontmatter, falls back to pure markdown.
#### API Versioning
```
# V1 (current)
GET /api/notes
# V2 (future)
GET /api/v2/notes # New features
GET /api/notes # Still works, returns V1 response
```
### Data Export/Import
#### Export Formats
1. **Markdown Bundle**: Zip of all notes (already portable)
2. **JSON Export**: Notes + metadata
```json
{
"version": "1.0",
"exported_at": "2024-11-18T12:00:00Z",
"notes": [
{
"slug": "my-note",
"content": "Note content...",
"created_at": "2024-11-01T12:00:00Z",
"published": true
}
]
}
```
3. **RSS Archive**: Existing feed.xml
#### Import (V2)
- From JSON export
- From WordPress XML
- From markdown directory
- From other IndieWeb CMSs
## Success Metrics
The architecture is successful if it enables:
1. **Fast Development**: < 1 week to implement V1
2. **Easy Deployment**: < 5 minutes to get running
3. **Low Maintenance**: Runs for months without intervention
4. **High Performance**: All responses < 300ms
5. **Data Ownership**: User has direct access to all content
6. **Standards Compliance**: Passes all validators
7. **Extensibility**: Can add V2 features without rewrite
## References
### Internal Documentation
- [Technology Stack](/home/phil/Projects/starpunk/docs/architecture/technology-stack.md)
- [ADR-001: Python Web Framework](/home/phil/Projects/starpunk/docs/decisions/ADR-001-python-web-framework.md)
- [ADR-002: Flask Extensions](/home/phil/Projects/starpunk/docs/decisions/ADR-002-flask-extensions.md)
- [ADR-003: Frontend Technology](/home/phil/Projects/starpunk/docs/decisions/ADR-003-frontend-technology.md)
- [ADR-004: File-Based Storage](/home/phil/Projects/starpunk/docs/decisions/ADR-004-file-based-note-storage.md)
- [ADR-005: IndieLogin Authentication](/home/phil/Projects/starpunk/docs/decisions/ADR-005-indielogin-authentication.md)
### External Standards
- [IndieWeb](https://indieweb.org/)
- [IndieAuth Spec](https://indieauth.spec.indieweb.org/)
- [Micropub Spec](https://micropub.spec.indieweb.org/)
- [Microformats2](http://microformats.org/wiki/h-entry)
- [RSS 2.0](https://www.rssboard.org/rss-specification)
- [Flask Documentation](https://flask.palletsprojects.com/)