feat: implement datastream support on elasticsearch-logger plugin

[jr-instantsystem]

Description

The current plugin allows to push messages to raw indices in ElasticSearch, using the "POST _bulk" endpoint, with the "_index" action.
It not compatible with DataSteams according to https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-bulk, where action have to be "_create" to push on DataStream.

The PR add a second plugin param for a datastream name. The user must choose between "index name" or "datastream name" to define the method used to push to ElasticSearch.

Tested on 3.12

Which issue(s) this PR fixes:

N/A

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)

[Baoyuantop]

Suggested change

	else if conf.field.datastream then
	elseif conf.field.datastream then

[jr-instantsystem]

thx

[Baoyuantop]

This check is unnecessary. The schema's oneOf constraint ensures that at least one of the index and datastream is set.

[jr-instantsystem]

code removed

[Baoyuantop]

We also need to add tests for this feature.

[Copilot]

Pull request overview

This PR updates the elasticsearch-logger plugin to support writing logs to either a classic Elasticsearch index or a DataStream target, and aligns the plugin documentation with the new configuration options.

Changes:

• Extend the plugin schema to allow configuring either field.index or field.datastream (mutually exclusive).
• Update bulk action generation to emit index vs create actions depending on the configured target.
• Document the new field.datastream attribute and update notes around required field configuration.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
docs/en/latest/plugins/elasticsearch-logger.md	Documents field.index / field.datastream options and updates notes about required configuration.
apisix/plugins/elasticsearch-logger.lua	Adds schema support and runtime logic to generate bulk entries for index vs datastream targets.

Comments suppressed due to low confidence (1)

apisix/plugins/elasticsearch-logger.lua:231

• When field.datastream is used, body is built with a create action and has no body.index, but the ES 5/6 compatibility block unconditionally writes body.index._type. This will throw a runtime error; set _type on the actual action present (e.g., body.index vs body.create) or restructure to avoid accessing body.index when using datastream.

    -- for older version type is required
    if conf._version == "6" or conf._version == "5" then
        body.index._type = "_doc"
    end

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[jr-instantsystem]

done