Jenkins Slave Permission Denied while copying slave.jar

Question

I get a permissions denied but don't know why. From my jenkins master I was able to run the following command using ssh-rsa-key

scp /var/cache/jenkins/war/WEB-INF/slave.jar jenkins@<my_slave_host>:/var/jenkins/

Note: I did manually create /var/jenkins/ on the my slave host when i saw it didn't exist and made it owned by the jenkins user. My master jenkins is configured to use the jenkins@mySlaveHost using .ssh keys.

Any ideas why I'm getting a permissions denied? What is it trying to do?

Here's the log from master jenkins after clicking [Lauch slave agent] button:

[02/27/15 15:18:01] [SSH] Opening SSH connection to <my_slave_host>:22.
[02/27/15 15:18:02] [SSH] Authentication successful.
[02/27/15 15:18:03] [SSH] The remote users environment is:
BASH=/bin/bash
BASHOPTS=cmdhist:complete_fullquote:extquote:force_fignore:hostcomplete:interactive_comments:progcomp:promptvars:sourcepath
BASH_ALIASES=()
BASH_ARGC=()
BASH_ARGV=()
BASH_CMDS=()
BASH_EXECUTION_STRING=set
BASH_LINENO=()
BASH_SOURCE=()
BASH_VERSINFO=([0]="4" [1]="3" [2]="11" [3]="1" [4]="release" [5]="x86_64-pc-linux-gnu")
BASH_VERSION='4.3.11(1)-release'
CATALINA_HOME=/opt/tomcat/current
DIRSTACK=()
EUID=107
GROUPS=()
HOME=/var/lib/jenkins
HOSTNAME=*********** REMOVED***********
HOSTTYPE=x86_64
IFS=$' \t\n'
JAVA_HOME=/usr/lib/jvm/java-7-oracle
LANG=en_US.UTF-8
LOGNAME=jenkins
MACHTYPE=x86_64-pc-linux-gnu
MAIL=/var/mail/jenkins
OPTERR=1
OPTIND=1
OSTYPE=linux-gnu
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
PIPESTATUS=([0]="0")
PPID=10592
PS4='+ '
PWD=/var/lib/jenkins
SHELL=/bin/bash
SHELLOPTS=braceexpand:hashall:interactive-comments
SHLVL=1
SSH_CLIENT='10.57.13.32 34436 22'
SSH_CONNECTION='10.57.13.32 34436 10.57.6.42 22'
TERM=dumb
UID=107
USER=jenkins
XDG_RUNTIME_DIR=/run/user/107
XDG_SESSION_ID=42
_=']'
[02/27/15 15:18:03] [SSH] Checking java version of java
[02/27/15 15:18:04] [SSH] java -version returned 1.7.0_76.
[02/27/15 15:18:04] [SSH] Starting sftp client.
[02/27/15 15:18:04] [SSH] Copying latest slave.jar...
hudson.util.IOException2: Could not copy slave.jar into '/var/jenkins' on slave
    at hudson.plugins.sshslaves.SSHLauncher.copySlaveJar(SSHLauncher.java:1019)
    at hudson.plugins.sshslaves.SSHLauncher.access$300(SSHLauncher.java:133)
    at hudson.plugins.sshslaves.SSHLauncher$2.call(SSHLauncher.java:709)
    at hudson.plugins.sshslaves.SSHLauncher$2.call(SSHLauncher.java:696)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: hudson.util.IOException2: Could not copy slave.jar to '/var/jenkins/slave.jar' on slave
    at hudson.plugins.sshslaves.SSHLauncher.copySlaveJar(SSHLauncher.java:1016)
    ... 7 more
Caused by: com.trilead.ssh2.SFTPException: Permission denied (SSH_FX_PERMISSION_DENIED: The user does not have sufficient permissions to perform the operation.)
    at com.trilead.ssh2.SFTPv3Client.openFile(SFTPv3Client.java:1201)
    at com.trilead.ssh2.SFTPv3Client.createFile(SFTPv3Client.java:1074)
    at com.trilead.ssh2.SFTPv3Client.createFile(SFTPv3Client.java:1055)
    at hudson.plugins.sshslaves.SFTPClient.writeToFile(SFTPClient.java:93)
    at hudson.plugins.sshslaves.SSHLauncher.copySlaveJar(SSHLauncher.java:1008)
    ... 7 more
[02/27/15 15:18:04] Launch failed - cleaning up connection
[02/27/15 15:18:04] [SSH] Connection closed.

Edit: Here's /var/jenkins on the slave:

$ ls -al
total 436
drwxr-xr-x  2 jenkins jenkins     22 Feb 27 15:17 .
drwxr-xr-x 14 root    root      4096 Feb 27 15:12 ..
-rw-r--r--  1 jenkins jenkins 439584 Feb 27 15:17 slave.jar

As for SFTP, I do not think it is enabled, can you point me to any docs that says SFTP is a pre-requisite for a slave? All the pages I've seen do not mention SFTP.

Answer 1

It looks like the problem is tied to your Remote root directory setting. That needs to be the location of the slave.jar, as Jenkins will try to execute it from there.

As for the permissions, the Remote Root Directory (whatever you set it to) needs to be configured to allow Jenkins to access it.

Therefore, if you change your Remote root directory setting to be /var/jenkins/ in your case, it should launch the Jenkins slave successfully.