BSL doesn't let you use software "in production" at all. So you wouldn't be able to offer search on your website with Elasticsearch at all, whether you could be construed to be reselling it or not, and whether your whole stack is opensource or not.
Also the SPDX identifier for it is BUSL since BSL was already taken by the Boost Software License.
Not true that it doesn’t allow production usage, it just doesn’t do it by default.
The intention is that it’s up to the one using the BUSL to specify to which degree production usage is allowed:
“The Licensor may make an Additional Use Grant, above, permitting limited production use.”
Eg. Sentry allows all non-SaaS production deployments of their BUSL licensed code, which is pretty much the same goal as here, but with BUSL the code will be actually open source eventually whereas here it will stay in this extended AGPL-like license forever?
Also the SPDX identifier for it is BUSL since BSL was already taken by the Boost Software License.