It is now clearer which nodes are Primary and which are Secondary on MongoDB Instance dashboards.

In PMM2, when you show nodes In PMM we are not able to know if a node is primary or secondary. 

When you do a compare and you have several nodes , it helps to be able to know what node is accepting the writes ( primary ) and what nodes are secondaries , in order to compare metrics. 

It is also good to know if a primary step down and becomes a secondary. We should be able to see the duration of monitoring , and a red line comes up when the primary stepped down. 

Proposed Solution:

Let's add to "MongoDB Instance summary" and to  "MongoDB instance Compare"  panels with the current status  of the instance (Secondary or  Primary)   and historical graph of this changes  (or we can have only graph if it  will be clear )