(feat) add /key/health endpoint to test key based logging (#6073)

* add /key/health endpoint

* add /key/health endpoint

* fix return from /key/health

* update doc string

* fix doc string for /key/health

* add test for /key/health

* fix linting

* docs /key/health

tests/otel_tests/test_key_logging_callbacks.py

@@ -0,0 +1,69 @@
+"""
+Tests for Key based logging callbacks
+
+"""
+
+import httpx
+import pytest
+
+
+@pytest.mark.asyncio()
+async def test_key_logging_callbacks():
+    """
+    Create virtual key with a logging callback set on the key
+    Call /key/health for the key -> it should be unhealthy
+    """
+    # Generate a key with logging callback
+    generate_url = "http://0.0.0.0:4000/key/generate"
+    generate_headers = {
+        "Authorization": "Bearer sk-1234",
+        "Content-Type": "application/json",
+    }
+    generate_payload = {
+        "metadata": {
+            "logging": [
+                {
+                    "callback_name": "gcs_bucket",
+                    "callback_type": "success_and_failure",
+                    "callback_vars": {
+                        "gcs_bucket_name": "key-logging-project1",
+                        "gcs_path_service_account": "bad-service-account",
+                    },
+                }
+            ]
+        }
+    }
+
+    async with httpx.AsyncClient() as client:
+        generate_response = await client.post(
+            generate_url, headers=generate_headers, json=generate_payload
+        )
+
+    assert generate_response.status_code == 200
+    generate_data = generate_response.json()
+    assert "key" in generate_data
+
+    _key = generate_data["key"]
+
+    # Check key health
+    health_url = "http://localhost:4000/key/health"
+    health_headers = {
+        "Authorization": f"Bearer {_key}",
+        "Content-Type": "application/json",
+    }
+
+    async with httpx.AsyncClient() as client:
+        health_response = await client.post(health_url, headers=health_headers, json={})
+
+    assert health_response.status_code == 200
+    health_data = health_response.json()
+    print("key_health_data", health_data)
+    # Check the response format and content
+    assert "key" in health_data
+    assert "logging_callbacks" in health_data
+    assert health_data["logging_callbacks"]["callbacks"] == ["gcs_bucket"]
+    assert health_data["logging_callbacks"]["status"] == "unhealthy"
+    assert (
+        "Failed to load vertex credentials"
+        in health_data["logging_callbacks"]["details"]
+    )