elasticsearchThe Rust client is largely generated from the REST API specs of Elasticsearch. As such, the API functions available align with the version of the specs from which they're generated. Elasticsearch strives to adhere to Semantic Versioning, which is reflected in the specs and thus this client.
What this means in practice is that a 7.x Rust client is compatible with Elasticsearch 7.x. Where the client minor version is greater than Elasticsearch minor version, it may contain API functions for APIs that are not available in the version of Elasticsearch, but all other API functions will be compatible. Where the client minor version is less than Elasticsearch minor version, all API functions will be compatible.
The project is still very much a work in progress and in an alpha state; input and contributions welcome!