Can I write a key-value pair to a datagroup from an iRule?

adam_webb, Three options off the top of my head...though 1. comes with a  "just because you can doesn't mean you should" warning label. 2. is probably the best path.

1. Call the iControl REST API from a sideband connection
2. Use ISTATS::set to push the key/value to an iCall script. The key would be set as part of the iStats key (it's a little complex to grok) and the value would just be the value. Example in this article I wrote on invalidating WA cache.
3. Push an entry to a local log file (like local0. that goes to /var/log/ltm) and create an alert in user_alert.conf that an iCall trigger can capture and act on. Example on an APM threshold crossing.