Feat: Add Langtrace integration (#5341)

* Feat: Add Langtrace integration

* add langtrace service name

* fix timestamps for traces

* add tests

* Discard Callback + use existing otel logger

* cleanup

* remove print statments

* remove callback

* add docs

* docs

* add logging docs

* format logging

* remove emoji and add litellm proxy example

* format logging

* format `logging.md`

* add langtrace docs to logging.md

* sync conflict

docs/my-website/docs/observability/langtrace_integration.md

@@ -0,0 +1,63 @@
+import Image from '@theme/IdealImage';
+
+# Langtrace AI
+
+Monitor, evaluate & improve your LLM apps
+
+## Pre-Requisites
+
+Make an account on [Langtrace AI](https://langtrace.ai/login)
+
+## Quick Start
+
+Use just 2 lines of code, to instantly log your responses **across all providers** with langtrace
+
+```python
+litellm.callbacks = ["langtrace"]
+langtrace.init()
+```
+
+```python
+import litellm
+import os
+from langtrace_python_sdk import langtrace
+
+# Langtrace API Keys
+os.environ["LANGTRACE_API_KEY"] = "<your-api-key>"
+
+# LLM API Keys
+os.environ['OPENAI_API_KEY']="<openai-api-key>"
+
+# set langtrace as a callback, litellm will send the data to langtrace
+litellm.callbacks = ["langtrace"]
+
+#  init langtrace
+langtrace.init()
+
+# openai call
+response = completion(
+    model="gpt-4o",
+    messages=[
+        {"content": "respond only in Yoda speak.", "role": "system"},
+        {"content": "Hello, how are you?", "role": "user"},
+    ],
+)
+print(response)
+```
+
+### Using with LiteLLM Proxy
+
+```yaml
+model_list:
+  - model_name: gpt-4
+    litellm_params:
+      model: openai/fake
+      api_key: fake-key
+      api_base: https://exampleopenaiendpoint-production.up.railway.app/
+
+litellm_settings:
+  callbacks: ["langtrace"]
+
+environment_variables:
+  LANGTRACE_API_KEY: "141a****"
+```

docs/my-website/docs/proxy/logging.md

@@ -1307,6 +1307,47 @@ curl --location 'http://0.0.0.0:4000/chat/completions' \
 Expect to see your log on Langfuse
 <Image img={require('../../img/langsmith_new.png')} />
 
+
+## Logging LLM IO to Langtrace
+
+1. Set `success_callback: ["langtrace"]` on litellm config.yaml
+
+```yaml
+model_list:
+  - model_name: gpt-4
+    litellm_params:
+      model: openai/fake
+      api_key: fake-key
+      api_base: https://exampleopenaiendpoint-production.up.railway.app/
+
+litellm_settings:
+  callbacks: ["langtrace"]
+
+environment_variables:
+    LANGTRACE_API_KEY: "141a****"
+```
+
+2. Start Proxy
+
+```
+litellm --config /path/to/config.yaml
+```
+
+3. Test it! 
+
+```bash
+curl --location 'http://0.0.0.0:4000/chat/completions' \
+--header 'Content-Type: application/json' \
+--data ' {
+      "model": "fake-openai-endpoint",
+      "messages": [
+        {
+          "role": "user",
+          "content": "Hello, Claude gm!"
+        }
+      ],
+    }
+'
 ## Logging LLM IO to Galileo
 
 [BETA]