[RFC 0052] Stage 2: Update additional GenAI fields

[susan-shu-c]

1. What does this PR do?

• Stage 0: [RFC] Stage 0: Add additional GenAI fields #2519
• Stage 1: [RFC 0052] Stage 1: Update GenAI fields #2525

2. Which ECS fields are affected/introduced?

Field	Type	Description /Usage
gen_ai.system_instructions	flattened	The system message or instructions provided to the GenAI model separately from the chat history.
gen_ai.input.messages	nested	The chat history provided to the model as an input.
gen_ai.output.messages	nested	Messages returned by the model where each message represents a specific model response (choice, candidate).
gen_ai.tool.definitions	nested	The list of source system tool definitions available to the GenAI agent or model.
gen_ai.tool.call.arguments	flattened	Parameters passed to the tool call.
gen_ai.tool.call.result	flattened	The result returned by the tool call (if any and if execution was successful).

Changes based on OTel:

• Using attributes for chat history on gen_ai spans and events open-telemetry/semantic-conventions#2179
• Add tool definition and other tool-related attributes in invoke-agent, inference, and execute-tool spans open-telemetry/semantic-conventions#2702

3. Why is this change necessary?

4. Have you added/updated documentation?

YES / NO / N/A

5. Have you built ECS and committed any newly generated files?

YES / NO

6. Have you run the ECS validation tests locally?

YES / NO

7. Anything else for the reviewers?

Looking for feedback

[Edit: see comment]

For the fields where it would be more useful to keep the associations and have more cases for searching, I changed the field type to nested, and for those that don't need the associations and probably don't need nested searching, I changed them to flattened.

For most of the fields, they are lists of .json objects, or .json objects. For fields whose content could be very long (input.messages, output.messages), I have proposed that they are the flattened type due to costs.

via docs for nested type:

When ingesting key-value pairs with a large, arbitrary set of keys, you might consider modeling each key-value pair as its own nested document with key and value fields. Instead, consider using the flattened data type, which maps an entire object as a single field and allows for simple searches over its contents. Nested documents and queries are typically expensive, so using the flattened data type for this use case is a better option.

Though as I am not a subject matter expert on the field types and efficiency, looking for additional feedback or comments.

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Commit Message

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Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)

[github-actions]

Documentation changes preview: https://docs-v3-preview.elastic.dev/elastic/ecs/pull/2532/reference/

[github-actions]

🔍 Preview links for changed docs

• docs/reference/ecs-gen_ai.md
• docs/reference/ecs-otel-alignment-details.md
• docs/reference/ecs-otel-alignment-overview.md

[trisch-me]

as stage 2 is a final stage, please update all examples and generate all fields

[susan-shu-c]

@flash1293 thanks a lot for explaining the tradeoffs. For the fields where it would be more useful to keep the associations and have more cases for searching, I changed the field type to nested, and for those that don't need the associations and probably don't need nested searching, I changed them to flattened. Really appreciate the help.

[flash1293]

Thanks @susan-shu-c - side note, do we have cases of existing nested and flattened ECS fields already?

[susan-shu-c]

Hi @flash1293 there are a few:

Flattened:
elf.exports
log.syslog.structured_data

Nested:
elf.sections
threat.enrichments

[susan-shu-c]

Thanks for the comments all. I've updated the following:

1. Cleaned up the rfcs/text/0052-gen_ai-additional-fields.md file to be on par with rfcs/text/0052/gen_ai.yaml, cleaned up unused comments.
2. Updated schemas/gen_ai.yml which Michael said the published schema will be taken from

However, when I try to run make clean generate experimental I am getting some unexpected behavior, where many .md files in docs is being deleted, trying to resolve with @mjwolf

Also getting a failure in tests

  File "/code/ecs/scripts/generators/otel.py", line 156, in __set_stability
    otel['stability'] = self.attributes[get_otel_attribute_name(field_details, otel)]['stability']
                        ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: 'gen_ai.output.messages'
make: *** [generator] Error 1

OTel reference: https://opentelemetry.io/docs/specs/semconv/registry/attributes/gen-ai/#gen-ai-output-messages

[Mikaayenson]

Migrating a slack thought to the issue for posterity. Here are a couple things we should consider before pushing this forward.

1. The default setting for limiting nested fields on indices ( index.mapping.nested_fields.limit ) is 50 . If customers try to create a new index with a higher limit, they will receive the following error: Settings [index.mapping.nested_fields.limit,index.mapping.nested_objects.limit] are not available when running in serverless mode. It's a serverless limitation that can't be overridden without Elastic support involved. ECH its much higher. I think like 10k and can be manually overridden.
2. IINM nested fields are not visible in Kibana visualizations. If there are any that we would imagine want to be visualized, it would be impacted, so we may want to consider changing them to flattened.

[trisch-me]

@susan-shu-c you error about not finding gen_ai.tool.call.arguments is because of this field not being released yet. Last known release (which I have merged to ecs today) doesn’t contain this field, i.e. we can’t say it’s an otel: match
As a workaround - we could skip otel definition for ecs fields for those fields that are not released yet but we should make sure it will not be forgotten, i.e. just comment them out for example

As an idea we can just always work against main in otel. There are no things deleted anymore, everything is deprecated.

[susan-shu-c]

hi, for now, I have marked the tool.call[...] fields as OTel related - in v1.37.0 it'd still be under gen_ai.operation.name (roughly speaking) - link