Duplicity is arguing BackendException: ssh connection to my server:22 failed: not a valid OPENSSH private key file - ssh

Question

Thanks to maybeg, I've managed to backup my data from home to an external server. (An amazon one)
As i don't want to backup company datas to Amazon, i tried with an internal backup server.
I then used this command. (I have my own key)
docker run -d --name volumerize
-v /MyFolder/Keys/:/MyFolder/Keys/
-v jenkins_volume:/source:ro
-v backup_volume:/backup
-e 'VOLUMERIZE_SOURCE=/source'
-e "VOLUMERIZE_TARGET=scp://myuser#mybackupserver/home/myuser/"
-e 'VOLUMERIZE_DUPLICITY_OPTIONS=--ssh-options "-i /MyFolder/Keys/myuserkey"'
-e 'PASSPHRASE="mypassphrase"' blacklabelops/volumerize
When using duplicity backup command, inside or outside the container, i have the following error
/usr/lib/python2.7/site-packages/paramiko/ecdsakey.py:200: DeprecationWarning: signer and verifier have been deprecated. Please use sign and verify instead.
signature, ec.ECDSA(self.ecdsa_curve.hash_object())
BackendException: ssh connection to myuser#mybackupserver:22 failed: not a valid OPENSSH private key file
Strangely, inside or outside the volumerize container, the following is running properly.
ssh -i /MyFolder/Keys/myuserkey myuser#mybackupserver
key_load_public: invalid format
Enter passphrase for key '/MyFolder/Keys/myuser':
[myuser#mybackupserver ~]$
Editing backup file for example is giving me the following :
#!/bin/bash
set -o errexit
source /etc/volumerize/stopContainers
duplicity $# --allow-source-mismatch --archive-dir=/volumerize-cache --ssh-options "-i /MyFolder/Keys/myuserkey" /source scp://myuser#mybackupserver/home/myuser/
source /etc/volumerize/startContainers
I've tried to check env variables inside the container, please find below what i have : (Note that passphrase has been added as env variable as found here)
HOSTNAME=b68f0e1a2d45
TERM=xterm
BLACKLABELOPS_HOME=/var/blacklabelops
GOOGLE_DRIVE_CREDENTIAL_FILE=/credentials/googledrive.cred
VOLUMERIZE_HOME=/etc/volumerize
VOLUMERIZE_SOURCE=/source
DOCKERIZE_VERSION=v0.5.0
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/etc/volumerize
VOLUMERIZE_TARGET=scp://myuser#mybackupserver/home/myuser/
PWD=/etc/volumerize
VOLUMERIZE_DUPLICITY_OPTIONS=--ssh-options "-i /MyFolder/Keys/myuserkey"
VOLUMERIZE_CACHE=/volumerize-cache
GPG_TTY=/dev/console
SHLVL=1
HOME=/root
no_proxy=*.local, 169.254/16
GOOGLE_DRIVE_SETTINGS=/credentials/cred.file
PASSPHRASE="mypassphrase"
_=/usr/bin/env
Can someone point me in the right direction ?
Regards,
pierre
Edit1 :
I tried to compare both private key file (Amazon and Company) using
openssl rsa -in yourkey.pem -check and both says
RSA key ok
writing RSA key
-----BEGIN RSA PRIVATE KEY-----
....
-----END RSA PRIVATE KEY-----
Edit2 :
1 . Had a look without any success at duplicity-backendexception
For information, Paramiko version is 2.2.1
Connection is successful using the following python script.
import paramiko
import StringIO
f = open('/MyFolder/Keys/myuserkey','r')
s = f.read()
keyfile = StringIO.StringIO(s)
mykey = paramiko.RSAKey.from_private_key(keyfile,password='mypassphrase')
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect('mybackupserver',username='mouser',pkey=mykey)
stdin, stdout, stderr = ssh.exec_command('uptime')
stdout.readlines()
[u' 12:35:27 up 3 days, 1:42, 0 users, load average: 1.59, 3.10, 3.00\n']

Answer 1

try the pexpect+scp:// backend (more on available ssh backends can be found in the duplicity manpage http://duplicity.nongnu.org/duplicity.1.html ).
it uses the command line ssh binaries. maybe the error is different or more detailed there?
the error on
ssh -i /MyFolder/Keys/myuserkey myuser#mybackupserver
key_load_public: invalid format
does not seem normal. try to provide the public key in the proper format or not at all.
..ede/duply.net