The third benefit of the Sentinel feat says (PHB, p. 169-170; emphasis mine):
- When a creature within 5 feet of you makes an attack against a target other than you (and that target doesn't have this feat), you can use your reaction to make a melee weapon attack against the attacking creature.
Thus, do shove and grapple attempts meet the requirement of a creature "making an attack"?
If so, does the shove or grapple attempt need to be successful in order to meet that condition from the quoted benefit of the Sentinel feat?
I suspect that the answer to the first part of my question is yes, given the answer to this similar question about the third benefit of the Mobile feat (PHB, p. 168), but I'm less sure about the second part of my question.
(I know that the reaction attack from Sentinel would only occur after the triggering attack by the enemy is resolved – though I know it could occur after the first attack by the enemy that meets this condition, so you don't have to wait for all of the enemy's attacks to finish, just one.)