Jenkins windows slave via openssh fails to start - jenkins

Question

I'm trying to connect a windows agent to jenkins with no luck. I'm using open ssh and no verification for now during setup. When I launch the agent, Jenkins can reach it and it puts the remote.jar in the requested folder, but it still has an issue starting the agent. I get no error description whatsoever
SSHLauncher{host='NLQA1', port=22, credentialsId='10314a78-c648-4891-aa78-c5510875e8e7', jvmOptions='', javaPath='c:/jenkins2/jdk/bin/java.exe', prefixStartSlaveCmd='', suffixStartSlaveCmd='', launchTimeoutSeconds=210, maxNumRetries=10, retryWaitTime=15, sshHostKeyVerificationStrategy=hudson.plugins.sshslaves.verifiers.NonVerifyingKeyVerificationStrategy, tcpNoDelay=true, trackCredentials=true}
[06/20/19 13:36:26] [SSH] Opening SSH connection to NLQA1:22.
[06/20/19 13:36:27] [SSH] WARNING: SSH Host Keys are not being verified. Man-in-the-middle attacks may be possible against this connection.
[06/20/19 13:36:28] [SSH] Authentication successful.
[06/20/19 13:36:28] [SSH] The remote user's environment is:
ALLUSERSPROFILE=C:\ProgramData
APPDATA=C:\Users\Admin\AppData\Roaming
CommonProgramFiles=C:\Program Files\Common Files
CommonProgramFiles(x86)=C:\Program Files (x86)\Common Files
CommonProgramW6432=C:\Program Files\Common Files
COMPUTERNAME=NLQA1
ComSpec=C:\WINDOWS\system32\cmd.exe
DriverData=C:\Windows\System32\Drivers\DriverData
GIT_SSH=C:\Program Files\TortoiseGit\bin\TortoisePLink.exe
HOMEDRIVE=C:
HOMEPATH=\Users\Admin
ICU_DATA=c:\Usd91\BIN
LOCALAPPDATA=C:\Users\Admin\AppData\Local
NUMBER_OF_PROCESSORS=2
OneDrive=C:\Users\Admin\OneDrive
OS=Windows_NT
Path=C:\app\client\Admin\product\12.1.0\client_1\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\WINDOWS\System32\OpenSSH\;C:\Program Files\Git\cmd;C:\Program Files\TortoiseGit\bin;C:\WINDOWS\system32\config\systemprofile\AppData\Local\Microsoft\WindowsApps;c:\Gnuwin32;C:\Users\Admin\AppData\Local\Microsoft\WindowsApps;C:\App;
PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC
PROCESSOR_ARCHITECTURE=AMD64
PROCESSOR_IDENTIFIER=Intel64 Family 6 Model 63 Stepping 2, GenuineIntel
PROCESSOR_LEVEL=6
PROCESSOR_REVISION=3f02
ProgramData=C:\ProgramData
ProgramFiles=C:\Program Files
ProgramFiles(x86)=C:\Program Files (x86)
ProgramW6432=C:\Program Files
PROMPT=Admin#Domain#NLQA1 $P$G
PSModulePath=C:\Program Files\WindowsPowerShell\Modules;C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules
PUBLIC=C:\Users\Public
SSH_CLIENT=172.x.x.x 63458 22
SSH_CONNECTION=172.x.x.x 63458 172.x.x.x 22
SystemDrive=C:
SystemRoot=C:\WINDOWS
TEMP=C:\TEMP
TMP=C:\TEMP
USERDOMAIN=Domain
USERNAME=Admin#Domain
USERPROFILE=C:\Users\Admin
windir=C:\WINDOWS
[06/20/19 13:36:28] [SSH] Starting sftp client.
[06/20/19 13:36:28] [SSH] Copying latest remoting.jar...
Source agent hash is D2D1A740134BD20D6F0855B356344342. Installed agent hash is D2D1A740134BD20D6F0855B356344342
Verified agent jar. No update is necessary.
Expanded the channel window size to 4MB
[06/20/19 13:36:29] [SSH] Starting agent process: cd "c:/jenkins2" && c:/jenkins2/jdk/bin/java.exe -jar remoting.jar -workDir c:/jenkins2
Slave JVM has terminated. Exit code=0
[06/20/19 13:36:29] Launch failed - cleaning up connection
[06/20/19 13:36:29] [SSH] Connection closed.
Agent is running adoptopenjdk 11 with eclipsej9, Slave JVM has terminated. Exit code=0 is all information I get back from Jenkins. I can run the agent if I rdp to the machine and do c:/jenkins2/jdk/bin/java.exe -jar remoting.jar -workDir c:/jenkins2 manually, so it is not that the jar can't be started at all. jnlp is working as well, but I'd like to use the ssh route. Do you have a clue what is wrong or what I have to do to get more information regarding the failed launch?

Answer 1

I found the answer at the ssh-slaves-plugin git repository. I'll quote it here so it will be here in the future.
Launch Windows slaves using Microsoft OpenSSH
The current version of the plugin does not run directly on PowerShell, you have to use prefix and suffix settings to trick the command and make it works, Windows 10 machines can run as SSH agents with the Microsoft OpenSSH server by using:
Prefix Start Agent Command
powershell -Command "cd C:\J\S ; C:\J\S\jdk\bin\java.exe -jar remoting.jar" ; exit 0 ; rem '
Suffix Start Agent Command
'
EDIT 16-08-2019
After installing windows updates on the machine I had to change the prefix to
powershell -Command "cd C:\J\S ; C:\J\S\jdk\bin\java.exe -jar remoting.jar" ; exit 0 ; # '
The change from rem to # make it working again. The error I was getting was :
The string is missing the terminator: '.
+ CategoryInfo : ParserError: (:) [], ParentContainsErrorRecordException
+ FullyQualifiedErrorId : TerminatorExpectedAtEndOfString
Looks like its the && operator. simple example
powershell -Command "cd c:/" ; exit 0 ; rem 'cd && echo "abc"'
Adding the prefix and the suffix fixed it for my. If someone knows why wrapping it in another powershell command makes it work feel free to elaborate.