Updated dockerfile and Added error handling & logging

Dockerfile

@@ -13,6 +13,10 @@ RUN pip install --upgrade pip
 COPY ./requirements.txt .
 RUN pip install -r requirements.txt
 
+# add user
+RUN adduser --disabled-password --gecos '' service
+USER service
+
 # copy project
 COPY . .
-ENTRYPOINT ["/usr/src/app/entrypoint.sh", "--user"]
+ENTRYPOINT ["/usr/src/app/entrypoint.sh"]

main.py

@@ -7,10 +7,15 @@ import os
 import json
 import smtplib
 import sys
+import time
 from email.header import Header
 from email.mime.text import MIMEText
 
 import cherrypy
+import logging
+
+logging.basicConfig(filename='app.log', filemode='w',
+                    format='%(name)s - %(levelname)s - %(message)s')
 
 
 class SMTPWebhookApp:
@@ -19,51 +24,87 @@ class SMTPWebhookApp:
     """
 
     def _send_mail(self):
-        try:
-            cl = cherrypy.request.headers['Content-Length']
-            rawbody = cherrypy.request.body.read(int(cl))
-            req_body = json.loads(rawbody)
-            subject = req_body['subject']
-            body = req_body['body']
-            client = smtplib.SMTP(host=SERVER_HOST, port=SERVER_PORT)
-            msg = MIMEText(body, 'plain', 'utf-8')
-            msg['Subject'] = Header(subject, 'utf-8')
-            msg['From'] = FROM_MAIL
-            msg['To'] = TO_MAIL
 
+        if not cherrypy.request.headers.get('Content-Length'):
+            logging.error("To: {}, error: Invalid content length.".format(
+                        TO_MAIL))
+            return {"status": 400, "message": "Invalid content length."}
+
+        cl = cherrypy.request.headers['Content-Length']
+        rawbody = cherrypy.request.body.read(int(cl))
+        req_body = json.loads(rawbody)
+
+        if not req_body.get('subject') or req_body.get('subject') == '':
+            logging.error("To: {}, error: body field is required.".format(
+                        TO_MAIL))
+            return {"status": 400, "message": "subject field is required."}
+
+        if not req_body.get('body') or req_body.get('body') == '':
+            logging.error("To: {}, error: body field is required.".format(
+                        TO_MAIL))
+            return {"status": 400, "message": "body field is required."}
+
+        subject = req_body['subject']
+        body = req_body['body']
+
+        try:
+            client = smtplib.SMTP(host=SMTP_SERVER_HOST, port=SMTP_SERVER_PORT)
+        except Exception as e:
+            time.sleep(0.2)
+            logging.error("To: {}, error: {}".format(TO_MAIL, e))
+            return {"status": 400, "message": "SMTP client error: {}.".format(
+                    e)}
+
+        msg = MIMEText(body, 'plain', 'utf-8')
+        msg['Subject'] = Header(subject, 'utf-8')
+        msg['From'] = FROM_MAIL
+        msg['To'] = TO_MAIL
+        try:
             client.ehlo()
             client.starttls()
             client.ehlo()
             client.login(msg["From"], FROM_MAIL_PASSWORD)
             client.sendmail(msg['From'], msg['To'], msg.as_string())
+            response = {"status": 200, "message": "mail sent successfully"}
+            logging.info("To: {}, mail sent successfully".format(TO_MAIL))
+        except smtplib.SMTPException as e:
+            time.sleep(0.2)
+            logging.error("To: {}, error: {}".format(TO_MAIL, e))
+            response = {"status": 500, "message": "some error: {}".format(e)}
+        finally:
             client.quit()
-            return "mail sent successfully"
-        except Exception as e:
-            return "some error: {}".format(e)
+            return response
 
     @cherrypy.expose
     def send_mail(self):
         """
         api endpoint for send mail
         """
-        return self._send_mail()
+        data = self._send_mail()
+        cherrypy.response.status = data["status"]
+        cherrypy.response.headers["Content-Type"] = "application/json"
+        return json.dumps(data["status"]).encode()
 
 
 ROOT = SMTPWebhookApp()
 
+SMTP_SERVER_PORT = 587
+CHERRYPY_SERVER_HOST = "0.0.0.0"
+CHERRYPY_SERVER_PORT = 8081
+
 if __name__ == "__main__":
     try:
-        SERVER_HOST = os.environ["server_host"]
-        SERVER_PORT = os.environ["server_port"]
-        TO_MAIL = os.environ["to_mail"]
-        FROM_MAIL = os.environ["from_mail"]
-        FROM_MAIL_PASSWORD = os.environ["from_mail_password"]
+        SMTP_SERVER_HOST = os.environ["SMTP_SERVER_HOST"]
+        TO_MAIL = os.environ["TO_MAIL"]
+        FROM_MAIL = os.environ["FROM_MAIL"]
+        FROM_MAIL_PASSWORD = os.environ["FROM_MAIL_PASSWORD"]
     except KeyError:
-        raise KeyError("Please check missing environment variables: to_mail, "
-                       "from_mail, from_mail_password")
+        raise KeyError("Please check missing environment variables: "
+                       "SMTP_SERVER_HOST, TO_MAIL, FROM_MAIL, "
+                       "FROM_MAIL_PASSWORD")
 
-    cherrypy.server.socket_host = "0.0.0.0"
-    cherrypy.server.socket_port = 8081
+    cherrypy.server.socket_host = CHERRYPY_SERVER_HOST
+    cherrypy.server.socket_port = CHERRYPY_SERVER_PORT
     ENGINE = cherrypy.engine
 
     cherrypy.tree.mount(ROOT, config={})