EXHIBIT 2

JOINT FILING AGREEMENT

The undersigned hereby agree to the joint filing of the Amendment No. 6 to Schedule 13D to which this Agreement is attached.

Dated:  June 1, 2017

	DISCOVERY EQUITY PARTNERS, L.P.
	By	Michael R. Murphy*
		Michael R. Murphy
		Manager
	DISCOVERY GROUP I, LLC
	By	Michael R. Murphy*
		Michael R. Murphy
		Manager
	*By:	/s/ Mark Buckley
		Mark Buckley
		Attorney-in-Fact for Michael R. Murphy