Error 500 when trying to send file from remote server (python code) to an SFTP server - python-3.x

Question

I have a Flask API in a Docker container where I do the following :
from flask import Flask, request
import os
import json
import paramiko
import subprocess
app = Flask(__name__)
#app.route("/")
def hello():
return "Service up in K8S!"
#app.route("/get", methods=['GET'])
def get_ano():
print("Test liveness")
return "Pod is alive !"
#app.route("/run", methods=['POST'])
def run_dump_generation():
rules_str = request.headers.get('database')
print(rules_str)
postgres_bin = r"/usr/bin/"
dump_file = "database_dump.sql"
os.environ['PGPASSWORD'] = 'XXXXX'
print('Before dump generation')
with open(dump_file, "w") as f:
result = subprocess.call([
os.path.join(postgres_bin, "pg_dump"),
"-Fp",
"-d",
"XX",
"-U",
"XX",
"-h",
"XX",
"-p",
"XX"
],
stdout=f
)
print('After dump generation')
transport = paramiko.Transport(("X", X))
transport.connect(username="X", password="X")
sftp = transport.open_sftp_client()
remote_file = '/data/database_dump.sql'
sftp.put('database_dump.sql', remote_file)
print("SFTP object", sftp)
if __name__ == "__main__":
app.run(host='0.0.0.0', debug=True)
When I run the app in Kubernetes with Post request I have the error : "POST /run HTTP/1.1" 500
Here are the requirements.txt:
Flask==2.0.1
paramiko==3.0.0
The error comes from transport = paramiko.Transport(("X", X)). The same code works locally. I don't understand why I have this error when I am on Kubernetes. But in the logs no print are displaying, I guess it is because I have error 500. I guess it is not possible with this code to send file from this container to the SFTP server (has OpenSSH).
What can I do ?
---- UPDATE ----
I think I have found the problem. In a Flask pod (VM) I try to send file from this pod to SFTP server. So I have to modify the following code to "allow" this type of send. This an SFTP server with OpenSSH.
Here is the code where to modify :
transport = paramiko.Transport(("X", X))
transport.connect(username="X", password="X")
sftp = transport.open_sftp_client()
remote_file = '/data/database_dump.sql'
sftp.put('database_dump.sql', remote_file)
print("SFTP object", sftp)
SFTP server (with OpenSSH) is alpine and Flask code is in Alpine container too.
UPDATE BELOW, I tried the following :
ssh=paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
session = ssh.connect(hostname="X", port=X, username='X', password="X")
print(ssh)
But I have the following error :
File "c:/Users/X/dump_generator_api/t.py", line 32, in <module>
session = ssh.connect(hostname="X", port=X, username='X', password="X")
File "C:\Users\X\AppData\Local\Programs\Python\Python38-32\lib\site-packages\paramiko\client.py", line 449, in connect
self._auth(
File "C:\Users\X\AppData\Local\Programs\Python\Python38-32\lib\site-packages\paramiko\client.py", line 780, in _auth
raise saved_exception
File "C:\Users\X\AppData\Local\Programs\Python\Python38-32\lib\site-packages\paramiko\client.py", line 767, in _auth
self._transport.auth_password(username, password)
File "C:\Users\X\AppData\Local\Programs\Python\Python38-32\lib\site-packages\paramiko\transport.py", line 1567, in auth_password
return self.auth_handler.wait_for_response(my_event)
File "C:\Users\X\AppData\Local\Programs\Python\Python38-32\lib\site-packages\paramiko\auth_handler.py", line 259, in wait_for_response
raise e
paramiko.ssh_exception.AuthenticationException: Authentication failed.