Create a file for service your-service

touch /etc/systemd/system/your-service.service 

Let’s assume you want to run docker container there. Put following text in the file:

[Unit]                                                                                                                                                                                                                                        
Description=YourService                                                                                                                                                                                                                           
After=docker.service                                                                                                                                                                                                                          
Requires=docker.service                                                                                                                                                                                                                       
                                                                                                                                                                                                                                              
[Service]                                                                                                                                                                                                                                     
TimeoutStartSec=0                                                                                                                                                                                                                             
Restart=always                                                                                                                                                                                                                                
ExecStartPre=-/usr/bin/docker stop %n                                                                                                                                                                                                         
ExecStartPre=-/usr/bin/docker rm %n                                                                                                                                                                                                           
ExecStart=/usr/bin/docker run -d -p 8080:8080/tcp --name %n your_docker_image
                                                                                                                                                                                                                                              
[Install]                                                                                                                                                                                                                                     
WantedBy=multi-user.target

Here we first stop and delete the docker container. If it doesn’t exist we continue (there is a “-” in before the command).

Run

systemctl enable your-service 

Commands

# prints the status
systemctl status your-service.service  

# prepares the service, required before "start", 
# also reloads the config if you changed the definition file  
systemctl enable levels_tracker.service 

# start service
systemctl start levels_tracker.service 

# stop service
systemctl stop levels_tracker.service 

Recipes

Specify working directory

[Service]
WorkingDirectory=/home/pi

Running python script from virtual environment

Just specify python interpreter from the environment:

ExecStart=<absolute path to your environment>/bin/python file_to_run.py

Environment variables

You can set environment variables that are used for your process

[Service]
Environment=VARIABLE=value

Now you can use it in the ExecStart command for example:

ExecStart=<absolute path to your environment>/bin/python file_to_run.py ${VARIABLE}

How to stdout of python-based service in syslog

Python buffers stdout. Therefore even if you have enable redirection of stdout to the syslog:

StandardOutput=syslog

You may see nothing in the logs. You should set environment variable for python PYTHONUNBUFFERED to see the results immediately:

#in your service file add to [Service] section:
Environment="PYTHONUNBUFFERED=1"

source: [here]

Probably better approach when you are allowed to install modules: https://medium.com/@trstringer/logging-to-systemd-in-python-45150662440a

See also:

[1]

[2] How To Use Systemctl to Manage Systemd Services and Units

[3] How to set up proper start/stop services