using lambda role in sns/publish-topic! about cljs-lambda

[moea]

I think the point you're raising about whether default-iam-credentials! ought to be able to auto-retrieve the correct region from the instance metadata is a good one - though I'm not sure that's what's operative here.

If this function is running on the Lambda infrastructure, environment variables are used to convey the appropriate function role - a map containing these can be retrieved via eulalie.creds/env - which just returns the map, not a channel, so something like:

(sns/publish-topic!
  (eulalie.creds/env)
  "arn:aws:sns:us-west-2:785400771354:parsehook-qa"
  (.stringify js/JSON event))

Ought to work. It sounds like you may want to do something else to communicate the region (and then assoc it onto the map returned by (env)), and I'm not sure the Lambda infrastructure facilitates this. Let me know if you think there's a way to make that bit easier.

N.B. Returning an error via async-lambda-fn's channel is how errors are reported, though they may be swallowed (or obscured, at best) with nested async calls - <? and go-catching (or just using <? + (go (try ...))) from https://github.com/nervous-systems/glossop may help with that - it's a transitive dep of your project already. There are examples of using it throughout eulalie and fink-nottle.

[keeth]

Got it working, thanks! Here's the working snippet:

(def ^:export publish-to-sns
  (async-lambda-fn
   (fn [event context]
     (go-catching
       (<! (sns/publish-topic!
             (assoc (eulalie.creds/env) :region "us-west-2")
             "arn:aws:sns:us-west-2:785400771354:parsehook-qa"
             (.stringify js/JSON (clj->js event))))))))