The Elasticsearch REST APIs are exposed over HTTP.
A number of Elasticsearch GET APIs—most notably the search API—support a request body.
While the GET action makes sense in the context of retrieving information,
GET requests with a body are not supported by all HTTP libraries.
All Elasticsearch GET APIs that require a body can also be submitted as POST requests.
Alternatively, you can pass the request body as the
source query string parameter
when using GET.
REST API version compatibilityedit
Major version upgrades often include a number of breaking changes that impact how you interact with Elasticsearch. While we recommend that you monitor the deprecation logs and update applications before upgrading Elasticsearch, having to coordinate the necessary changes can be an impediment to upgrading.
You can enable an existing application to function without modification after an upgrade by including API compatibility headers, which tell Elasticsearch you are still using the previous version of the REST API. Using these headers allows the structure of requests and responses to remain the same; it does not guarantee the same behavior.
You set version compatibility on a per-request basis in the
compatible-with to the same major version as
the version you’re running has no impact,
but ensures that the request will still work after Elasticsearch is upgraded.
To tell Elasticsearch 8.0 you are using the 7.x request and response format,
Content-Type: application/vnd.elasticsearch+json; compatible-with=7 Accept: application/vnd.elasticsearch+json; compatible-with=7