I’m using a REST API based integration and rely on the http-01 for the validation on the /.well-known/acme-challenge/ endpoint.
I noticed that the staging server is currently making 4 validation calls (from 4 different IPs), while the production one just 1 call.
Is there a way to find out how many validation calls will there be made before the validation can be considered completed and successful? I couldn’t find such information in the integration guide so far.
There is not - we explicitly do not want clients making assumptions about the state of validation based on the requests received. Your client should begin polling the authorization to monitor its status once you have POSTed a challenge. The authorization status is the definitive source for when validation is considered complete and successful.
There is not. We have some optimization work to do that is blocked by higher priority work (ACMEv2, wildcard issuance, SCT embedding).
Monitoring the API announcements category of the forum is the best way to find out when this change will be activated in production. We'll post in there ahead of the change to give notice.