We are going to learn where are all the Drupal logs in our system. What types of messages exist and how to log the different types of messages. 

We are also going to create a custom module, with the help of which we are going to log messages as a new node is created. For that, we are going to be using the hook_entity_insert function in our .module file.

Here is the video on how to inject a service into another service:
https://youtu.be/M7fZT0tfxV4

Drupal.org on the Logging API + example how to inject the logging service into another service:
https://www.drupal.org/docs/8/api/logging-api/overview

Here is a video on how to inject a service into a custom form:
https://youtu.be/89DQM1t78rs?t=318

The full code of the module you may find here:
https://github.com/drupal-up/drupalup_logexample