It’s been a while since I needed to configure Netflow and I’ve never actually done it on any of Cisco’s recent software. After the usual wading through their horrible documentation and incorrect examples I finally have something that will work:

flow record TRAFFIC-RECORD
 description traffic record
 match ipv4 source address
 match ipv4 destination address
 collect counter bytes long
 collect counter packets long
 collect timestamp absolute first
 collect timestamp absolute last
flow monitor TRAFFIC
 description traffic monitor
 record TRAFFIC-RECORD
 ip flow monitor TRAFFIC input
 ip flow monitor TRAFFIC output