It seems like there's a gap in the Analytics Admin 1.4 around rules. First, I don't see an endpoint to get standard processing rules. I've checked all of the endpoints listed on GitHub:
1) "processing rules" are not available through API 1.4. at least I haven't seen them either
2) I would guess the the eVar is "eVar123", because the key "rule_id" is rather the id for the element in this rule than the real ruleID (which is 345)
ursboller very true, but it can't hurt to try 🙂 I would of course love to get the admin endpoints in the 2.0 API, it's a pain to switch back and forth between the launch and analytics 1.4 APIs.
Regarding #2, 123 was just a placeholder for the real id, since I didn't know if those were meaningful. The ID did not contain the eVar number. So I created a ticket for that as well:
Processing Rules API is not available in 1.4 or 2.0 at this time, including read -only API methods. Processing Rule changes are currently restricted to the user interface. There is no announced timeline for when this functionality will be available by API.