mail/src/app.py

from flask import Flask, request, jsonify
from prometheus_flask_exporter import PrometheusMetrics
import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.mime.application import MIMEApplication
import os
import time
import html
import re
import logging


class FilterRemoveDate(logging.Filter):
	# '192.168.0.102 - - [30/Jun/2024 01:14:03] "%s" %s %s' -> '192.168.0.102 - "%s" %s %s'
	pattern: re.Pattern = re.compile(r' - \[.+?]')

	def filter(self, record: logging.LogRecord) -> bool:
		record.msg = self.pattern.sub('', record.msg)
		return True

class FilterReplaceWerkzeug(logging.Filter):
	# 'werkzeug:' -> 'app:flask:'
	pattern: re.Pattern = re.compile(r'werkzeug:')

	def filter(self, record: logging.LogRecord) -> bool:
		record.msg = self.pattern.sub('app:flask:', record.msg)
		return True

class FilterReplaceLowercaseI(logging.Filter):
	# 'I:' -> 'i:'
	pattern: re.Pattern = re.compile(r'I:')

	def filter(self, record: logging.LogRecord) -> bool:
		record.msg = self.pattern.sub('i:', record.msg)
		return True

# Setup logger
logging.basicConfig(
	level=logging.DEBUG,
	format='%(asctime)s.%(msecs)03dZ %(name)s:%(levelname).1s: %(message)s',
	datefmt='%Y-%m-%d %H:%M:%S'
)

logger = logging.getLogger('app')
logger_werkzeug = logging.getLogger('werkzeug')
logger_werkzeug.addFilter(FilterRemoveDate())
logger_werkzeug.addFilter(FilterReplaceWerkzeug())
logger_werkzeug.addFilter(FilterReplaceLowercaseI())

app = Flask(__name__, static_folder=None)

# Wrap the Flask app with PrometheusMetrics
metrics = PrometheusMetrics(app, defaults_prefix="mail")

email_sent_counter = metrics.counter(
	'mail_text_sent_total',
	'Total number of text messages sent',
	labels={'endpoint': lambda: request.endpoint}
)

pdf_sent_counter = metrics.counter(
	'mail_pdf_sent_total',
	'Total number of pdfs sent',
	labels={'endpoint': lambda: request.endpoint}
)


@app.route('/v1')
@metrics.do_not_track()
def info():
	today = time.strftime("%Y-%m-%d")
	url_map = app.url_map
	return f"<h1>mail v1.0.0 - {today}</h1><pre>" + html.escape(str(url_map), False) + "</pre>"


@app.route('/v1/send/message', methods=['POST'])
@email_sent_counter
def send_message():
	logger = logging.getLogger('app:send-message')
	data = request.json
	subject = data.get('subject')
	text_content = data.get('message')
	to_email = data.get('to_email')
	html_content = data.get('html')

	logger.info(f"Sending text email to {to_email}")
	logger.debug(f"Subject: {subject}")

	# SMTP Configuration
	smtp_server = os.environ.get('SMTP_RELAY_HOST')
	smtp_port = int(os.environ.get('SMTP_RELAY_PORT'))
	smtp_username = os.environ.get('SMTP_RELAY_USERNAME')
	smtp_password = os.environ.get('SMTP_RELAY_PASSWORD')

	try:
		# Create a message
		msg = MIMEMultipart('mixed')
		msg['From'] = smtp_username
		msg['To'] = to_email
		msg['Subject'] = subject

		# Create the multipart/alternative part
		msgAlternative = MIMEMultipart('alternative')
		msg.attach(msgAlternative)

		# Attach plain text message first (lower priority)
		msgAlternative.attach(MIMEText(text_content, 'plain', 'utf-8'))

		# Attach HTML version if provided (higher priority)
		if html_content:
			logger.debug("HTML content included in email")
			msgAlternative.attach(MIMEText(html_content, 'html', 'utf-8'))

		# Send email
		logger.debug(f"Connecting to SMTP server {smtp_server}:{smtp_port}")
		with smtplib.SMTP_SSL(smtp_server, smtp_port) as smtp:
			smtp.login(smtp_username, smtp_password)
			smtp.sendmail(smtp_username, to_email, msg.as_string())
			smtp.quit()

		logger.info("Email sent successfully")
		return jsonify({"message": "Email sent successfully"}), 200
	except Exception as e:
		logger.error(f"Error sending email: {str(e)}")
		return jsonify({"error": str(e)}), 500


@app.route('/v1/send/pdf', methods=['POST'])
@pdf_sent_counter
def send_pdf():
	logger = logging.getLogger('app:send-pdf')
	data = request.form
	subject = data.get('subject')
	text_content = data.get('message')
	html_content = data.get('html')
	to_email = data.get('to_email')
	pdf_blob = request.files.get('pdf_blob')

	logger.info(f"Sending PDF email to {to_email}")
	logger.debug(f"Subject: {subject}")

	# SMTP Configuration
	smtp_server = os.environ.get('SMTP_RELAY_HOST')
	smtp_port = int(os.environ.get('SMTP_RELAY_PORT'))
	smtp_username = os.environ.get('SMTP_RELAY_USERNAME')
	smtp_password = os.environ.get('SMTP_RELAY_PASSWORD')

	try:
		# Create a message with mixed content (attachments + text)
		msg = MIMEMultipart('mixed')
		msg['From'] = smtp_username
		msg['To'] = to_email
		msg['Subject'] = subject

		# Create the multipart/alternative part for text and HTML
		msgAlternative = MIMEMultipart('alternative')
		msg.attach(msgAlternative)

		# Attach plain text message first (lower priority)
		msgAlternative.attach(MIMEText(text_content, 'plain', 'utf-8'))

		# Attach HTML version if provided (higher priority)
		if html_content:
			logger.debug("HTML content included in email")
			msgAlternative.attach(MIMEText(html_content, 'html', 'utf-8'))

		# Attach PDF if provided
		if pdf_blob:
			logger.debug("Attaching PDF to email")
			pdf_attachment = MIMEApplication(pdf_blob.read(), _subtype="pdf")
			pdf_attachment.add_header('Content-Disposition', 'attachment', filename='document.pdf')
			msg.attach(pdf_attachment)
		else:
			logger.warning("No PDF attachment provided")

		# Send email
		logger.debug(f"Connecting to SMTP server {smtp_server}:{smtp_port}")
		with smtplib.SMTP(smtp_server, smtp_port) as smtp:
			logger.debug("SMTP connection established")
			try:
				smtp.starttls()
				logger.debug("STARTTLS successful")
			except Exception as e:
				logger.error(f"STARTTLS failed: {str(e)}")

			smtp.login(smtp_username, smtp_password)
			smtp.sendmail(smtp_username, to_email, msg.as_string())
			logger.debug("Email sent via SMTP")

		logger.info("PDF email sent successfully")
		return jsonify({"message": "Email sent successfully"}), 200
	except Exception as e:
		logger.error(f"Error sending PDF email: {str(e)}")
		return jsonify({"error": str(e)}), 500


@app.route('/health', methods=['GET'])
def health_check():
	logger = logging.getLogger('app:health-check')
	health_status = {'status': 'ok'}

	# Check SMTP configuration
	smtp_server = os.environ.get('SMTP_RELAY_HOST')
	smtp_port = os.environ.get('SMTP_RELAY_PORT')
	smtp_username = os.environ.get('SMTP_RELAY_USERNAME')

	if not all([smtp_server, smtp_port, smtp_username]):
		logger.error("SMTP configuration incomplete")
		health_status['smtp_config'] = False
		health_status['status'] = 'error'
	else:
		health_status['smtp_config'] = True

	# Try to connect to SMTP server
	try:
		smtp_port_int = int(smtp_port)
		use_ssl = smtp_port_int == 465

		if use_ssl:
			with smtplib.SMTP_SSL(smtp_server, smtp_port_int, timeout=5) as smtp:
				smtp.ehlo()
				health_status['smtp_responding'] = True
		else:
			with smtplib.SMTP(smtp_server, smtp_port_int, timeout=5) as smtp:
				smtp.ehlo()
				health_status['smtp_responding'] = True

	except Exception as e:
		logger.error(f"SMTP connection test failed: {str(e)}")
		health_status['smtp_responding'] = False
		health_status['status'] = 'error'

	logger.debug(f"Health check performed: {health_status}")
	return jsonify(health_status)


if __name__ == '__main__':
	app.run(host='0.0.0.0', port=2222, debug=False)