We Keep Coding

Run python GUI application as service on ubuntu 18.04

I've successfully manage to run my GUI python application as a service in a Raspberry pi. The used unit file:
[Unit]
Description=Example systemd service.
After=graphical.target
[Service]
Type=simple
Environment="Display=:0"
Environment=XAUTHORITY=/home/pi/.Xauthority
WorkingDirectory=/home/pi/tf/
ExecStart=/home/pi/tf/myApp.py
Restart=always
RestartSec=10s
KillMode=process
Timeout=infinity
[Install]
WantedBy=graphical.target
At the beginning of my python application i added the route python3 like this:
#! /address/where/is/python3
The problem is that i can't do the same in Ubuntu.
I think is because .Xauthority file does not exist.
In ubuntu i ran
echo $XAUTHORITY
and i got:
/run/user/1000/Xauthority
then i change these lines:
Environment=XAUTHORITY=/run/user/1000/Xauthority
WorkingDirectory=/home/sergio/tf/
ExecStart=/home/sergio/tf/myApp.py
with "journalctl -u myApp -f" displays the following error:
cannot connect to X server
Any idea what can it be?

I solve this problem by following the steps by htorque in this post https://askubuntu.com/questions/21923/how-do-i-create-the-xauthority-file
Follow this steps:
1-Open System > Preferences > Startup Applications
2-Click on Add :
3-Name: Xauthority
4-Command: /bin/bash -c 'ln -s -f "$XAUTHORITY"
~/.Xauthority' Comment: Creates a symbolic link from ~/.Xauthority to
$XAUTHORITY and add the entry by clicking on Add.
Now every time you log in, it should create the link to the current
authority file.
So now we have the file .Xauthority in ~/
Finally service file myApp.service was updated like this:
Environment="Display=:0"
Environment=XAUTHORITY=/home/"yourUsername"/.Xauthority

Kafka Producer and Consumer Scripts to Run automatically

I have a Django project and I am using pykafka. I have created two files named producer.py and consumer.py inside the project. I have to change directory into the folder where these are present and then separately run python producer.py and consumer.py from the terminal. Everything works great.
I deployed my project online and the web-app is running so I want to run the producer and consumer automatically in the background. How do i do that?
EDIT 1: On my production server I did nohup python name_of_python_script.py & to execute it in the background. This works for the time being but is it a good solution?

You can create a systemd service MyKafkaConsumer.service under /etc/systemd/system with the following content:
[Unit]
Description=A Kafka Consumer written in Python
After=network.target # include any other pre-requisites
[Service]
Type=simple
User=your_user
Group=your_user_group
WorkingDirectory=/path/to/your/consumer
ExecStart=python consumer.py
TimeoutStopSec=180
Restart=on-failure
RestartSec=5
[Install]
WantedBy=multi-user.target
In order to start the service (and configure it in order to run on boot) you should run
systemctl enable MyKafkaConsumer.service
systemctl start MyKafkaConsumer.service
To check its status:
systemctl status MyKafkaConsumer
And to see the logs:
journactl -u MyKafkaConsumer -f
(or if you want to see the last 100 lines)
journalctl -u MyKafkaConsumer -n 100
You'd need to create a similar service for your producer too.
There are a lot of options for systemd services. You can refer to this article if you need any further clarifications. It shouldn't be hard to find guides and additional material online though.

Start django app as service

I want to create service that will be start with ubuntu and will have ability to use django models etc..
This service will create thread util.WorkerThread and wait some data in main.py
if __name__ == '__main__':
bot.polling(none_stop=True)
How I can to do this. I just don't know what I need to looking for.
If you also can say how I can create ubuntu autostart service with script like that, please tell me )
P.S. all django project run via uwsgi in emperor mode.

The easiest way in my opinion is create a script and run on crontab.
First of all create a script to start your django app.
#!/bin/bash
cd /path/to your/virtual environment #path to your virtual environment
. bin/activate #Activate your virtual environment
cd /path/to your/project directory #After that go to your project directory
python manage.py runserver #run django server
Save the script and open crontab with the command:
crontab -e
Now edit the crontab file and write on the last line:
#reboot path/to/your/script.sh
This way is not the best but the easiest, if you are not comfortable with Linux startup service creation.
I hope this help you :)

Take a look at supervisord. It is much easier than daemonizing python script.
Config it something like this:
[program:watcher]
command = /usr/bin/python /path/to/main.py
stdout_logfile = /var/log/main-stdout.log
stdout_logfile_maxbytes = 10MB
stdout_logfile_backups = 5
stderr_logfile = /var/log/main-stderr.log
stderr_logfile_maxbytes = 10MB
stderr_logfile_backups = 5

Ok, that is answer - https://www.raspberrypi-spy.co.uk/2015/10/how-to-autorun-a-python-script-on-boot-using-systemd/
In new versions ubuntu services .conf in /etc/init fail with error Unable to connect to Upstart: Failed to connect to socket /com/ubuntu/upstart: Connection refused
But services works using systemd

Creating a startup service for python script to run as root in Arch Linux

I have a python script that I want to run on start up as root. I believe that I need to add it as a service file but I don't know if it has root permission. This is how i have my service file. The python file wont run unless in root.
[Unit]
Description= Description here
[Service]
Type=simple
ExecStart=/usr/bin/python /home/script.py
StandardOutput=null
[Install]
WantedBy=multi-user.target
Alias=script.service
Any help will be appreciated.

Got it to work. After I removed the root check from my python script everything worked fine, i also removed the Type=simple part from the service file. After those two things it worked fine.
the root check part i removed was.
from os import getenv
user = getenv("SUDO_USER")
if user is None:
print ("This program needs to run as root")
exit(0)
and the service file now looks like this
[Unit]
Description= Description here
[Service]
ExecStart=/usr/bin/python /home/script.py
StandardOutput=null
[Install]
WantedBy=multi-user.target
Alias=script.service
I still don't understand why I needed to take out the root check, program ran fine when I used sudo python script.py. For some reason when the script was ran with systemctl it would fail the root check.

Systemd runs multi-user services as root, so I don't see what help do you need.

Deploying CherryPy (daemon)

I've followed the basic CherryPy tutorial (http://www.cherrypy.org/wiki/CherryPyTutorial). One thing not discussed is deployment.
How can I launch a CherryPy app as a daemon and "forget about it"? What happens if the server reboots?
Is there a standard recipe? Maybe something that will create a service script (/etc/init.d/cherrypy...)
Thanks!

Daemonizer can be pretty simple to use:
# this works for cherrypy 3.1.2 on Ubuntu 10.04
from cherrypy.process.plugins import Daemonizer
# before mounting anything
Daemonizer(cherrypy.engine).subscribe()
cherrypy.tree.mount(MyDaemonApp, "/")
cherrypy.engine.start()
cherrypy.engine.block()
There is a decent HOWTO for SysV style here.
To summarize:
Create a file named for your application in /etc/init.d that calls /bin/sh
sudo vim /etc/init.d/MyDaemonApp
#!/bin/sh
echo "Invoking MyDaemonApp";
/path/to/MyDaemonApp
echo "Started MyDaemonApp. Tremble, Ye Mighty."
Make it executable
sudo chmod +x /etc/init.d/MyDaemonApp
Run update-rc.d to create our proper links in the proper runtime dir.
sudo update-rc.d MyDaemonApp defaults 80
sudo /etc/init.d/MyDaemonApp

There is a Daemonizer plugin for CherryPy included by default which is useful for getting it to start but by far the easiest way for simple cases is to use the cherryd script:
> cherryd -h
Usage: cherryd [options]
Options:
-h, --help show this help message and exit
-c CONFIG, --config=CONFIG
specify config file(s)
-d run the server as a daemon
-e ENVIRONMENT, --environment=ENVIRONMENT
apply the given config environment
-f start a fastcgi server instead of the default HTTP
server
-s start a scgi server instead of the default HTTP server
-i IMPORTS, --import=IMPORTS
specify modules to import
-p PIDFILE, --pidfile=PIDFILE
store the process id in the given file
As far as an init.d script goes I think there are examples that can be Googled.
And the cherryd is found in your:
virtualenv/lib/python2.7/site-packages/cherrypy/cherryd
or in: https://bitbucket.org/cherrypy/cherrypy/src/default/cherrypy/cherryd

I wrote a tutorial/project skeleton, cherrypy-webapp-skeleton, which goal was to fill the gaps for deploying a real-world CherryPy application on Debian* for a web-developer. It features extended cherryd for daemon privilege drop. There's also a number of important script and config files for init.d, nginx, monit, logrotate. The tutorial part describes how to put things together and eventually forget about it. The skeleton part proposes a way of possible arrangement of CherryPy webapp project assets.
* It was written for Squeeze but practically it should be same for Wheezy.

Info on Daemonizer options
When using Daemonizer, the docs don't state the options, e.g. how to redirect stdout or stderr. From the source of the Daemonizer class you can find the options. As a reference take this example from my project:
# run server as a daemon
d = Daemonizer(cherrypy.engine,
stdout='/home/pi/Gate/log/gate_access.log',
stderr='/home/pi/Gate/log/gate_error.log')
d.subscribe()