I have a command that I would like to create a service from. For example: "java -jar agent.jar" (the command is blocking - when closing the cmd it will stop the agent). I would like to make the command run as a service in the background so I can log out from my user and it will still work.
On Linux, I know for a fact that I can use nohup mycommand. The problem is on Windows OS. Also, replace java with javaw will solve the blocking issue but when I sign out it will still kill the agent.
How do I do that?
I'll appreciate your help!
Tomer.
Use Windows services feature.
Read this answer.
And this solution.
Related
I have a script.sh that set some environment variable and start a java server.
#!/bin/bash
export JAVA_HOME="/opt/java"
export ....
nohup $JAVA_HOME/bin/java "$MEMORY_JAVA_OPS" -classpath "$MY_CLASSPATH" $MAIN_CLASS &
I would like to transform this script (now is launched by /etc/rc.d/rc.local) in a service.
I tried many examples found online and over StackOverflow.
I created myservice.service file using many templates found online... No one work!
one example is:
[Unit]
Description=MyService Java Process Restart Upstart Script
After=auditd.service systemd-user-sessions.service time-sync.target
[Service]
User=root
TimeoutStartSec=0
Type=simple
KillMode=process
#export JAVA_HOME=/opt/java/jdk-9
#export PATH=$PATH:$JAVA_HOME/bin
WorkingDirectory=/tmp/myworkdir
ExecStart=/path/to/myscript.sh
[Install]
WantedBy=multi-user.target
With some configurations, the service starts but the status command says that it is dead (while it is actually running). With others it does not start. With none it stops with the command stop ....
I tried Type=Simple, forking, oneshot... always some problem.
I would simply that after boot or when user launch systemctl start myservice, service start, and if after some time crash will be started again. And if I will run systemclt stop myservice it stops and not need to kill the process.
Firstly it need to be said, that concept "service" greatly differs in Linux/Unix and Windows environment. From your question seems to me you are looking for Unix solution.
In unix you typically register some statup and stop script/command. The startup script just runs your java application via java -jar app.jar. This application does business logic & also opens listening on some SHUTDOWN port.
The stop script/command just invokes another (or the same with different cmd parameters) java application which does nothing else just sending STOP command to original application's SHUTDOWN port.
You can look in more detail for example on tomcat startup/stop scripts - they are doing exactly this.
For windows is better to use some wrappers like WinRun4J or whatever else. Of course you can have one multiplatform maven archetype for "universal multiplatform" service like we do.
EDITED:
If you are still unsure how to configure it on Linux, read https://linuxconfig.org/how-to-create-systemd-service-unit-in-linux
ExecStart will be the startup java -jar app.jar and ExecStop will be the stopping command java -jar app-stopper.jar
This question already has answers here:
How to Daemonize a Java Program?
(11 answers)
Closed 7 years ago.
I have built a little daemon in Java and I would like to run it as a service under Unix (e.g. Debian 5). I have read that there is a possibility of using a Java wrapper, but isn't there any other option which is easier to implement? Can't I just use a Unix command such as xxx java -jar program.jar?
Well, if you want to run your java program even when you exit out of your shell, the following is the most simple way:
$nohup java -jar program.jar &
You need to create an appropriate script in /etc/init.d and link it to /etc/rcX.d directories. The script should support at least start, stop, and status parameters. During start it should run java command with appropriate arguments, probably via nohup java <arguments> &. Then you should save PID of your newly-started process to file /var/run/yourservice.pid. stop command should read this PID file and kill this service.
The details vary from distribution to distribution, most distributions provide some macros to make whole job easier. It's best to look at examples of other services in /etc/init.d for your distribution.
Additionally:
If your service isn't accessed from other computers from the network, but it opens some port, make it unavailable with firewall.
If your service processes some 'delicate' data, it's good to add another user and invoke an appropriate sudo command in your /etc/init.d file.
You can start it as:
java -jar program.jar
Unix daemons are normally started by init or started by a script in /etc/init.d or /etc/rc.d, and started at specific runlevels - normally by soft links in /etc/rcX.d. (where X is the intended "runlevel" which is normally 3.
I think debian are moving to using "upstart", a init-replacement. It uses config files in /etc/init to define jobs, and they are quite easy to write. Check that out.
Daemons traditionally closes stdin, sdtout and stderr, and does a "double fork" when starting, in order to detach from the session and also to signal that they are ready to handle whatever they should handle. This is not really necessary, as long as the daemon is not started from the terminal.
If you want a simple shell wrapper to start you program; you just need to write a small shell script:
#!/bin/sh
/full/path/to/java -jar /full/path/to/program.jar
... and make it executable (chmod 755 )
This article contains a few useful tricks for running a Java application as a daemon:
http://barelyenough.org/blog/2005/03/java-daemon/
Alternatively, you can have a look at the Apache Commons Daemon project, although this requires native code (Unix and Win32 supported):
http://commons.apache.org/daemon/
You can use a cron job to schedule your program. You can also check out this article for details on how to run scripts on startup. You can write a script that runs your java program and run it on startup as mentioned in the article.
Have you had experience with running a jar file using a command line, wrapped in a Windows service?
I'm trying to find a way to run a jar file without being logged into the machine, and since it allows command shell, I was wondering if it's a good idea.
Thanks!
Original Post:
I'm trying to run Associated Press's Web Feeds Manager, which is basically a jar file that can be run when logged in by double clicking it.
I'd like to run the same file but without being logged in to the machine. In their manual (http://wfm.ap.org/admin/content/help/Running_Agent_on_a_Remote_Server.htm) they write how to do that, using a commandline parameter.
Basically I'd like the jar to run as a Windows service, regardless of who's logged in, but Googling it showed it was problematic.
Have you had experience with remotely running jar files? What are the pitfalls?
Thanks!
On a google search, I came across this article -
Running Jar Applications as a Windows Service
It mentions about open source Java Service Wrapper project from Tanukisoftware.org for accomplishing this task.
Note: I've not used this personally.
If you are not interested in having the service started/stopped at boot/shutdown, but you just want the program to be started manually and keep running after logout, here is what you do:
$ nohup java -jar foobar.jar > foobar.log 2>&1 &
which means: start my foobar.jar (java -jar) and keep it running after I logout (nohup) redirect stdout to foobar.log (>) and also the stderr (2>&1), and make it running in background (& at the end).
Instead, if you are interested in installing a "service" in your linux box, there are many options, depending on what distribution you are using.
The most common are upstart (for ubuntu) and System V init scripts (Redhat or others). Also cron can be used to start/stop services at startup/shutdown.
You can find an example of installing a java app (hudson) on an init system here, or doing the same thing with upstart. Or, as I said, cron could be an option.
On Windows, there is Java Service Wrapper. And not much more.
For windows Java Service Wrapper is a better choice
My favourite is the upstart on linux, but it is Ubuntu only.
On Windows I see many alternatives according to this forum.
So I have the following problem: I have a web service running inside a Tomcat7 server on Linux. The web service however has to execute some commands (mostly file operations such as copy and mount). Copy I've replaced with java.nio, but I don't think that there is a replacement for mount.
So I'm trying to execute shell commands out of my Tomcat Java process. Unfortunately it doesn't execute my commands. I've implemented the execution of shell commands in Java before. So my code should be correct:
Process pr = Runtime.getRuntime().exec("mount -o loop -t iso9660 <myimage> <mymountpoint>");
pr.waitFor();
<myimage> and <mymountpoint> are absolute paths, so no issues there either.
I've debugged my commands and they are working when executed on the console.
I've tried sending other commands. Simple commands such as id and pwd are working!
I've tried using /bin/bash -c "<command>", which didn't work.
I've tried executing a shell script, which executes the command, which didn't work.
I've tried escaping the spaces in my command, which didn't work.
So I've digged even deeper and now I'm suspecting some Tomcat security policy (Sandbox?), which prevents me from executing the command. Since security is no issue for me (it's an internal system, completely isolated from the outside world), I've tried a hack, which became quite popular just recently:
System.setSecurityManager(null);
This didn't work either. I'm using Java7 and Tomcat7 on RHEL6. Tomcat7 is just extracted! I don't have any files in /etc/.. or any other folder than /opt/tomcat/, where I've extracted the zip from the Tomcat home page. I've searched the /opt/tomcat/conf folder for security settings, but all I could find was the file catalina.policy, where it didn't seem like I could set some security level for shell commands.
Any ideas?
A few things:
System.setSecurityManager(null);
you have just killed the security of your application.
Yes, Tomcat is running as root. If I execute id I'm root as well.
Fix this immediately!
Now on to the question. You shouldnt have Tomcat executing anything, you need to defer this to a separate process whether that be a shell script or another Java program. This should also remove what (I hope) was a dependency on root running Tomcat. It should be possible to perform this command as a non-privileged user that cannot log into the system normally. You would do this by configuring /etc/fstab and supplying that same user the permissions to do this. From a pure security POV the process that mounts should not be owned by the tomcat user. Nor should the tomcat user ever be root. So to recap:
1) Stop running Tomcat as root
2) Create a separate process outside of the context of Tomcat to run this mount
3) Create a tomcat user, this user should not be able to log into the system nor should it be a privileged user (admin,super user, etc)
4) Create a process user, this user should be configured exactly as the tomcat user
5) Edit /etc/fstab giving the process user the necessary permissions to mount correctly.
It's generally a bad idea to use the single-string form of Runtime.exec. A better option is to use ProcessBuilder, and split up the arguments yourself rather than relying on Java to split them for you (which it does very naïvely).
ProcessBuilder pb = new ProcessBuilder("/bin/mount", "-o", "loop", /*...*/);
pb.redirectErrorStream(true); // equivalent of 2>&1
Process p = pb.start();
You say you're on RHEL so do you have selinux active? Check your logs and see if this is what's blocking you (I think it's audit.log you're looking for, it's been a few years since I've used selinux). If this does turn out to be the problem then you should probably ask on superuser or serverfault rather than SO...
I'm not sure if that's the problem you are having, but I've seen issues when Runtime.exec() is used without reading the associated output buffers. You can find a detailed explanation and potential solutions here. Reading the output and error streams can also help you figure out what's going on at the OS level when you run the command.
I've recently had to do something like this from a Swing app.
You'll probably be able to pull it off with ProcessBuilder, as in Ian's answer, but I found that once things start to get complex, it's easier to write a shell script that does what you want, enabling you to pass as few parameters as possible. Then use ProcessBuilder to invoke the shell script.
If you're invoking anything that has more than really minimal output, you'll also have to read the output and error streams to keep the process from blocking when the output buffers fill, as it seems you are already doing.
I use sudo -S before command and for the tomcat7 user: tomcat7 ALL=(ALL) NOPASSWD:ALL
I just found out that javaws -wait doesn't do what is supposed to do on Windows. It will return before the aplication finishes.
This bug is more than 5 years old and closed as won't fix
6281477, so we need a workaround.
I looking for a clean solution that will:
run unattended (no user intervention):
currently if JNLP file is not accessible, Java will display an error window.
if application fails for any reason we need a return code different from 0
It would be preferable to have a cross platform solution for this Java or Python but it would be acceptable even a Windows batch solution.
If you don't need your application to be booted from the web (which, from your question, I assume is the case), use javaw instead.
I believe it will give what you want.
I know this question is pretty old, but here is an alternative to javaws -wait: javaws will start a javaw process with com.sun.javaws.Main as main class.
The jcmd can come to the rescue:
while jcmd com.sun.javaws.Main PerfCounter.print > /dev/null 2> /dev/null ; do
echo "still running !"
sleep 2
done
One down side of this is to determine the actual java cmd: if multiple webstart application are ran, then the command will exit only if all application are down.