Is there a ready-made software for managing the settings (configuration) of self-written services at runtime?

Question

System administration

I am looking for software for centralized management of configurations (settings) of services of my own design.
I would like to receive from such software:

• nice web interface,
  
• roles/privileges/users,
  
• API for managed software,
  
• API for managing configurations (for example, to develop a nice web interface),
  
• service status monitoring is not required in this software
  

These requirements stem from the desire to manage certain aspects of the operation of services without stopping them.
For example, there is such a scenario:
There is a service for generating reports. Currently, the service generates an H report every 12 hours. But I wanted to change the frequency of report generation: instead of 12 hours, set 3 hours. I can't stop the service because it is serving other clients at the moment. And such a desire to change the frequency (or something else) I have at the request of the left heel of the customer.
I see this solution with the help of the desired software:

1. when finalizing the current version of the reporting service, I implement a mechanism for remotely receiving settings in it or open the ability to accept requests to change settings,
   
2. reporting service starts
   
3. the reporting service at startup accesses the desired software, receives the settings, and starts to perform its function according to these settings,
   
4. the user enters the web interface of the desired software, logs in,
   
5. the user changes the setting that determines the frequency of generating the report H,
   
6. the desired software makes a request to the reporting service and passes it the setting "report H every 3 hours",
   
7. the report service makes a report H every 3 hours,
   
8. i'm happy =)
   

I can not find a ready (!) solution. Help me please.
PS there is a suspicion that I am approaching the search from the wrong side, maybe I need to look for "monitoring", since the management of services is "attached". Don't know.

Answer 1

Self-written services will require a self-written management system.

Answer 2

If Windows-only, then MMC. Just that the interface is not web.
If you are looking for a cross-platform solution, then you can offer an LDAP directory. It meets all the requirements, there are a bunch of ready-made management tools.

Answer 3

If I understand you correctly, then try consul from hashicorp. There is a web interface, there is key-value storage, events and much more.