chore(telemetry): store internal event context in middleware

Note: This is a relatively high priority item for #491 (comment 2006453847).

What does this merge request do and why?

This MR does a groundwork for feat(tracking): add internal events framework t... (!902 - merged) and Track a product usage event with the new standa... (#491 - closed) by storing the internal event context in middleware.

These stored contexts are later by fetched by InternalEventTracker to send a complete event to snowplow (See this MR for overall implementation). The current event context can be fetched in the following way:

from ai_gateway.internal_events import current_event_context, EventContext

context: EventContext = current_event_context.get()

How to set up and validate locally

Test request:

curl -X 'POST' \
  'http://0.0.0.0:5052/v1/chat/agent' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -H 'X-Gitlab-Realm: saas' \
  -H 'X-Gitlab-Instance-Id: 123' \
  -H 'X-Gitlab-Host-Name: example.gitlab.com' \
  -H 'X-Gitlab-Version: 17.0' \
  -H 'X-Gitlab-Global-User-Id: 123abc' \
  -d '{
  "prompt_components": [
    {
      "type": "string",
      "metadata": {
        "source": "string",
        "version": "string"
      },
      "payload": {
        "content": "\n\nHuman: Hi, How are you?\n\nAssistant:",
        "provider": "anthropic",
        "model": "claude-2.1",
        "params": {
          "stop_sequences": [
            "\n\nHuman",
            "Observation:"
          ],
          "temperature": 0.2,
          "max_tokens_to_sample": 2048
        },
        "model_endpoint": "string",
        "model_api_key": "string"
      }
    }
  ],
  "stream": false
}'

Confirm that the context attributes are set properly:

context: environment='development' source='curl/7.81.0' realm='saas' instance_id='123' host_name='example.gitlab.com' instance_version='17.0' global_user_id='123abc'

patch

diff --git a/ai_gateway/api/v1/chat/agent.py b/ai_gateway/api/v1/chat/agent.py
index 3145c5e7..9c2d92c4 100644
--- a/ai_gateway/api/v1/chat/agent.py
+++ b/ai_gateway/api/v1/chat/agent.py
@@ -28,6 +28,7 @@ from ai_gateway.models import (
 )
 from ai_gateway.models.base_text import TextGenModelChunk, TextGenModelOutput
 from ai_gateway.tracking import log_exception
+from ai_gateway.internal_events import current_event_context, EventContext
 
 __all__ = [
     "router",
@@ -74,6 +75,9 @@ async def chat(
     ),
     litellm_factory: Factory = Depends(get_chat_litellm_factory_provider),
 ):
+    context: EventContext = current_event_context.get()
+    print(f"context: {context}")
+
     prompt_component = chat_request.prompt_components[0]
     payload = prompt_component.payload

Numbered steps to set up and validate the change are strongly suggested.

Merge request checklist

• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.