Difference between Controller Services in UI

[#1]

When creating controller services, it was noticed that there are 2 mentions of it in the UI.

One is within the root canvas wherein you can click on the cog icon and can reach controller settings from there.

The other way is to click on the list icon, on the right of the 'log out' text, and controller settings can be accessed from there.

The question is, whats the difference between the two? Creating it in A does not show up in B and vice versa.

Are there specific use cases for this differentiation?

What is the best way to implement controller services if we want to make it available to all process groups only to read and connect to those sources but not modify them.

[#2 · Accepted solution]

This is described in the user guide here:

https://nifi.apache.org/docs/nifi-docs/html/user-guide.html#Controller_Services

Controller services for processors must be defined from the context palette on the left.