from flask import Flask, request, jsonify
import logging
app = Flask(__name__)
# Configure logging to print to stdout (visible in docker logs)
logging.basicConfig(
level=logging.INFO,
format='%(asctime)s - %(levelname)s - %(message)s'
)
logger = logging.getLogger(__name__)
@app.route('/')
def index():
"""Main route that logs headers and returns HTML."""
x_forwarded_for = request.headers.get('X-Forwarded-For', 'Not set')
x_real_ip = request.headers.get('X-Real-IP', 'Not set')
# Log to console
logger.info(f"--- Request to / ---")
logger.info(f"X-Forwarded-For: {x_forwarded_for}")
logger.info(f"X-Real-IP: {x_real_ip}")
return f"""
Header Test
Headers Received
X-Forwarded-For: {x_forwarded_for}
X-Real-IP: {x_real_ip}
/testheaders - JSON output
/allheaders - All headers
Check docker logs for detailed output.
"""
@app.route('/testheaders')
def testheaders():
"""
Dedicated route for testing header propagation.
Returns all headers as JSON for easy programmatic verification.
"""
# Capture all headers
all_headers = dict(request.headers)
# Specifically extract the ones we care about
x_forwarded_for = request.headers.get('X-Forwarded-For', 'MISSING')
x_real_ip = request.headers.get('X-Real-IP', 'MISSING')
# Log the specific values
logger.info(f"--- Request to /testheaders ---")
logger.info(f"X-Forwarded-For: {x_forwarded_for}")
logger.info(f"X-Real-IP: {x_real_ip}")
# Return JSON response
return jsonify({
"status": "success",
"headers_received": {
"X-Forwarded-For": x_forwarded_for,
"X-Real-IP": x_real_ip,
"Host": request.headers.get('Host'),
"User-Agent": request.headers.get('User-Agent')
},
"all_headers": all_headers
}), 200
@app.route('/allheaders')
def allheaders():
"""
Route that displays ALL headers received.
Useful for debugging what Nginx is actually forwarding.
"""
# Get all headers as a dictionary
all_headers = dict(request.headers)
# Log each header for debugging
logger.info("--- Request to /allheaders ---")
for key, value in all_headers.items():
logger.info(f"{key}: {value}")
# Create HTML table for readability
header_rows = ''.join([
f'{key} {value} All Headers
All Headers Received
Total Headers: {len(all_headers)}
Header Name Value
Check docker logs for timestamped output.
"""
if __name__ == '__main__':
app.run(host='0.0.0.0', port=8080)
Add Dockerfile:
FROM python:3.11-slim
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
ENV TZ=Europe/Malta
COPY app.py .
EXPOSE 8080
CMD ["python", "app.py"]
Build the image and run:
docker build -t header-test-app .
docker run -d --name app-container -p 8080:8080 --network