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Launching Windows Jenkins Agents without JNLP

Built a new Windows Server 2016 to act as a target for jenkins orchestrated builds. We are not supposed to use oracle java anymore, so I got coretta openJDK. OpenJDK does not support javaws any more. The executable does not ship with it. I have seen some scripted workarounds, but they do not work and are poorly written to boot.
What are we supposed to use to launch slave agents on Windows machines?

There are several ways to implement this but since this is a windows server you can follow steps on https://github.com/kohsuke/winsw/blob/master/doc/installation.md#winsw-installation-guide to install jenkins slave as service without javaws.

I believe #Mike was referring to: Install Slave as a Windows service (cmd version), which does not need JNLP/javaws.
OR, under Jenkins 2 (we are using 2.121.1 plus WMI Windows Agents (aka windows-slaves:1.4), there is now an option to "Let Jenkins control this Windows slave as a Windows service", essentially in the same fashion as a Linux node.
You must have an Admin account (and password). We had to follow the guidance to edit registry when "Windows agents fail to start via DCOM" (Guidance is for Server 2012) to remotely manage the service. So far, seems to be working OK, YMMV. So far, seems to be working OK, no "subtle probelms"; YMMV.
For entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Wow6432Node\CLSID{72C24DD5-D70A-438B-8A42-98424B88AFB8}
HKEY_CLASSES_ROOT\CLSID{76A64158-CB41-11D1-8B02-00600806D9B6}
(There are several matches for the keys; just change the two locations indicated)
Launch 'regedit' (as Administrator)
Find (Ctrl+F) the following registry key: "{72C24DD5-D70A-438B-8A42-98424B88AFB8}" in
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Wow6432Node\CLSID\
Right click and select 'Permissions'
Change owner to administrators group (Advanced...).
Change permissions for administrators group. Grant Full Control.
Change owner back to TrustedInstaller (user is "NT Service\TrustedInstaller" on local machine)
Repeat the steps 1-6 for HKEY_CLASSES_ROOT\CLSID{76A64158-CB41-11D1-8B02-00600806D9B6}
Restart Remote Registry Service (Administrative Tools / Services)

For me the easiest and best working solution to launch Windows Jenkins Agents without JNLP was to run in the command prompt java -jar agent.jar ... command. The command parameters should be grabbed from the url of the agent:
http://your_jenkins_url/computer/your_agent_name_or_ip/
I downloaded the agent.jar on my PC, moved it to a desired directory, launched the Command Prompt from the dir where the agent.jar was moved and executed the proposed command with the appropriate parameters.
In my case:
java -jar agent.jar -jnlpUrl http://your_jenkins_url/computer/your_agent_name_or_ip/slave-agent.jnlp -secret 76986574e97c2b635c7076740dc93326eaaf5a3ad30573144915489a1ccfee44 -workDir "D:\jenkins"
This was one of the proposed approaches in the docs here - https://www.jenkins.io/doc/administration/requirements/upgrade-java-guidelines/
Java Web Start Java Web Start has been removed in Java 11. When a
Jenkins controller is running on Java 11, the Java Web Start button
will no longer appear in the Web UI. Agents for a Java 11 Jenkins
server can’t be launched from a *.jnlp file downloaded to a web
browser.
There are no plans to replace this functionality. Connect agents to
Jenkins on Java 11 with plugins like SSH Build Agents Plugin, with
operating system command line calls to java -jar agent.jar, or by
using containers.

How to connect to remote WildFly using JMC?

I have a Linux server where I'm running WildFly 10. I work on a Windows machine and I want to profile the remote application server. I've checked that port 9990 is enabled for access via http by accessing http://<ip>:9990/console and via JMX access from the JConsole client that comes in WildFly. For the latter, I downloaded WildFly to my machine, went to %WILDFLY_PATH%\bin\jconsole.bat, accesed through service:jmx:http-remoting-jmx://<ip>:9990 and used my credentials, it works properly. Now I want to access vía JMC, but I cannot achieve it. I tried the following:
Copied jboss-client.jar libraries from %WILDFLY_PATH%\bin\client to %JDK_HOME%\lib\missioncontrol\dropins and start JMC.
Executed JMC from cmd and added -cp:a <location of jboss-client.jar> param, like this:
jmc.exe -cp:a "C:\Program Files\Java\jdk1.8.0_72\lib\missioncontrol\dropins\jboss-client.jar"
None of these worked.
I tried access with VisualVM and worked using the last approach but replaced jmc.exe by jvisualvm.exe and I connected to the external VM with no issues. I wonder if there's any way to achieve this using JMC.

Since jmc doesn't accept the -cp flag, you have to run like this:
jmc.exe -vmargs -Xbootclasspath/a:<location of jboss-client.jar>
Some more clues might be here: https://community.oracle.com/thread/2592885?tstart=0

Jconsole Remote Executable Jar File

All,
I have a remote server that I recently enabled VNC for using vnc4server and Chicken for mac as the client.
The purpose for doing so was to enable running Java's Jconsole to monitor an executable jar file that is running my server logic.
However, after logging into my server using VNC, I keep getting an error when I try to use Jconsole on vnc.
It states connection failed do you want to try again. Now I am logged in as the same user that started the process.
Is there something I am missing when using jconsole in VNC? Also can I monitor my executable jar file remotely using Jconsole on my local machine?
These are the options I am including to run the jar file: java -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=9005 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.remote.ssl=false -Djava.rmi.server.hostname=ipaddress -jar path
Thanks
These JVM options fixed things. Fix found here: You need to pass to the VM: -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.local.only=false
https://forums.oracle.com/thread/1177644

This does not seem like an VNC issue- either the ports are not open, they are being blocked b a firewall, or there is some kind of permission/authentication issue with the app itself related to monitoring it.
In order to eliminate VNC as the cause (and use localhost in a local connection on jconsole), do "ssh -X REMOTHOST -n jconsole" and see. This will also eliminate the overhead of running the full X server and VNC.
Also on linux you can find out what process holds a port open by doing:
netstat -ap | grep PORT_NUMBER on the remote host you want to run on.
Colin

Starting Jetty via launch script does not work

I have a problem with starting Jetty via the startup command /etc/init.d/jetty. When I execute the command the following output is generated:
/etc/init.d/jetty start
Starting Jetty servlet engine.:
Jetty Rotate logs
Jetty servlet engine started, reachable on http://jagadguru:80/.: jetty.
It does start successfully when I type java -jar start.jar in my Jetty directory.
Can anyone help me with this?

This is likely a file permission issue. Even if you are running the start script with sudo, the script defines a jetty user (default is jetty). I had an issue similar to this where my permissions on /tmp prevented jetty from creating a file there. I adjusted the permissions on /tmp and all is well! The jetty user also needs permissions on the jetty folder of course.
Also, for checking if Jetty is finding java correctly, run sudo service jetty check

It's probably an issue due to wrong permissions on some work or log folder. I assume the start script tries to change the user and therefore doesn't has the same permissions as the one you use when running Jetty via "java -jar".
Another possibility is that you don't have JAVA_HOME set and the start script doesn't find your java bin.
Please attach some kind of log file as it is really hard to say more without more detailed information.

As answered here, the default configuration for Jetty in /etc/default/jetty only allows connections from localhost, you need to set JETTY_HOST to 0.0.0.0 to allow Jetty to accept connections from any host.
Add the following line to /etc/default/jetty:
JETTY_HOST 0.0.0.0

How to do memory profiling on remote java web application

I know we can use tools like JProfiler etc.
Is there any tutorial on how to configure it to display the memory usage just by remote monitoring?
Any idea?

you have VisualGC, it's not very advanced but you can see the memory usage of your application (garbage,old, perm etc...)
http://java.sun.com/performance/jvmstat/visualgc.html
to resume :
you launch a daemon monitoring on the remote machine (http://java.sun.com/j2se/1.5.0/docs/tooldocs/share/jstatd.html, see the security parapraph)
JAVA_HOME/bin/jstatd -J-Djava.security.policy=jstatd.all.policy
with a file here called jstatd.all.policy containing :
grant codebase "file:${java.home}/../lib/tools.jar" {
permission java.security.AllPermission;
};
on the remote machine you got the pid of your application to debug with the jps tool :
http://java.sun.com/j2se/1.5.0/docs/tooldocs/share/jps.html#jps
finally on your local machine you launch the visualgc :
visualgc the_pid#remote_machine_address

I usually use YourKit which is an excellent application (license needed).
In your webservers startup/shutdown script (catalina.sh for tomcat) put in:
JAVA_OPTS="-Djava.awt.headless=true -agentlib:yjpagent -Xrunyjpagent:sessionname=Tomcat"
You'll need YourKit already downloaded and added to your library path (I do this in catalina.sh as well):
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:~/yourkit/yjp-6.0.16/bin/linux-x86-32
You can then launch the YourKit client on your local desktop and remotely connect.

You can change to VM params of your Java application to allow remote profiling
something like -agentlib:jprofilerti=port=25000
General explanation of JProfiler.
Examples:
NetBeans
Intellij

Profile your application using Jprofiler. Below are the steps to configure your Tomcat with Jprofiler.
In Linux machine open .bash_profile file from /root directory.
Enter jprofiller location (using below command export) in
.bash_profile file
export LD_LIBRARY_PATH=/dsvol/jprofiler6/bin/linux-x86
Go Tomcat installation directory. Open catalena.sh file from bin folder.
Enter the below details in catelana.sh file (only red color information and black color you can find by default in catalena.sh file).
export JPROFILER_HOME
JAVA_OPTS="-Xms768m -Xmx1024m -XX:PermSize=256m -XX:MaxPermSize=256m -Dfile.encoding=UTF8 -agentpath:/opt/Performance/jprofiler7/bin/linux-x86/libjprofilerti.so=port=8849 $CATALINA_OPTS"
Start the server from bin folder by executing the starup.sh command

I've heard good things of VisualVM and here is an article on how to it up remotely:
Java VisualVM to profile a remote server
EDIT:
I wrote a blog post on how to setup remote profiling through an SSH tunnel here:
http://kamilmroczek.com/2012/11/16/168787859/