added tags to langchain

Author: mubashir1osmani

docs/my-website/docs/langchain/langchain.md

@@ -162,3 +162,321 @@ Get more details [here](../observability/lunary_integration.md)
 
 ## Use LangChain ChatLiteLLM + Langfuse
 Checkout this section [here](../observability/langfuse_integration#use-langchain-chatlitellm--langfuse) for more details on how to integrate Langfuse with ChatLiteLLM.
+
+## Using Tags with LangChain and LiteLLM
+
+Tags are a powerful feature in LiteLLM that allow you to categorize, filter, and track your LLM requests. When using LangChain with LiteLLM, you can pass tags through the `extra_body` parameter in the metadata.
+
+### Basic Tag Usage
+
+<Tabs>
+<TabItem value="openai" label="OpenAI">
+
+```python
+import os
+from langchain_openai import ChatOpenAI
+from langchain_core.messages import HumanMessage, SystemMessage
+
+os.environ['OPENAI_API_KEY'] = "sk-your-key-here"
+
+chat = ChatOpenAI(
+    model="gpt-4o",
+    temperature=0.7,
+    extra_body={
+        "metadata": {
+            "tags": ["production", "customer-support", "high-priority"]
+        }
+    }
+)
+
+messages = [
+    SystemMessage(content="You are a helpful customer support assistant."),
+    HumanMessage(content="How do I reset my password?")
+]
+
+response = chat.invoke(messages)
+print(response)
+```
+
+</TabItem>
+
+<TabItem value="anthropic" label="Anthropic">
+
+```python
+import os
+from langchain_openai import ChatOpenAI
+from langchain_core.messages import HumanMessage, SystemMessage
+
+os.environ['ANTHROPIC_API_KEY'] = "sk-ant-your-key-here"
+
+chat = ChatOpenAI(
+    model="claude-3-sonnet-20240229",
+    temperature=0.7,
+    extra_body={
+        "metadata": {
+            "tags": ["research", "analysis", "claude-model"]
+        }
+    }
+)
+
+messages = [
+    SystemMessage(content="You are a research analyst."),
+    HumanMessage(content="Analyze this market trend...")
+]
+
+response = chat.invoke(messages)
+print(response)
+```
+
+</TabItem>
+
+<TabItem value="litellm-proxy" label="LiteLLM Proxy">
+
+```python
+import os
+from langchain_openai import ChatOpenAI
+from langchain_core.messages import HumanMessage, SystemMessage
+
+# No API key needed when using proxy
+chat = ChatOpenAI(
+    openai_api_base="http://localhost:4000",  # Your proxy URL
+    model="gpt-4o",
+    temperature=0.7,
+    extra_body={
+        "metadata": {
+            "tags": ["proxy", "team-alpha", "feature-flagged"],
+            "generation_name": "customer-onboarding",
+            "trace_user_id": "user-12345"
+        }
+    }
+)
+
+messages = [
+    SystemMessage(content="You are an onboarding assistant."),
+    HumanMessage(content="Welcome our new customer!")
+]
+
+response = chat.invoke(messages)
+print(response)
+```
+
+</TabItem>
+</Tabs>
+
+### Advanced Tag Patterns
+
+#### Dynamic Tags Based on Context
+
+```python
+import os
+from langchain_openai import ChatOpenAI
+from langchain_core.messages import HumanMessage, SystemMessage
+
+def create_chat_with_tags(user_type: str, feature: str):
+    """Create a chat instance with dynamic tags based on context"""
+    
+    # Build tags dynamically
+    tags = ["langchain-integration"]
+    
+    if user_type == "premium":
+        tags.extend(["premium-user", "high-priority"])
+    elif user_type == "enterprise":
+        tags.extend(["enterprise", "custom-sla"])
+    else:
+        tags.append("standard-user")
+    
+    # Add feature-specific tags
+    if feature == "code-review":
+        tags.extend(["development", "code-analysis"])
+    elif feature == "content-gen":
+        tags.extend(["marketing", "content-creation"])
+    
+    return ChatOpenAI(
+        openai_api_base="http://localhost:4000",
+        model="gpt-4o",
+        temperature=0.7,
+        extra_body={
+            "metadata": {
+                "tags": tags,
+                "user_type": user_type,
+                "feature": feature,
+                "trace_user_id": f"user-{user_type}-{feature}"
+            }
+        }
+    )
+
+# Usage examples
+premium_chat = create_chat_with_tags("premium", "code-review")
+enterprise_chat = create_chat_with_tags("enterprise", "content-gen")
+
+messages = [HumanMessage(content="Help me with this task")]
+response = premium_chat.invoke(messages)
+```
+
+#### Tags for Cost Tracking and Analytics
+
+```python
+import os
+from langchain_openai import ChatOpenAI
+from langchain_core.messages import HumanMessage, SystemMessage
+
+# Tags for cost tracking
+cost_tracking_chat = ChatOpenAI(
+    openai_api_base="http://localhost:4000",
+    model="gpt-4o",
+    temperature=0.7,
+    extra_body={
+        "metadata": {
+            "tags": [
+                "cost-center-marketing",
+                "budget-q4-2024",
+                "project-launch-campaign",
+                "high-cost-model"  # Flag for expensive models
+            ],
+            "department": "marketing",
+            "project_id": "campaign-2024-q4",
+            "cost_threshold": "high"
+        }
+    }
+)
+
+messages = [
+    SystemMessage(content="You are a marketing copywriter."),
+    HumanMessage(content="Create compelling ad copy for our new product launch.")
+]
+
+response = cost_tracking_chat.invoke(messages)
+```
+
+#### Tags for A/B Testing
+
+```python
+import os
+from langchain_openai import ChatOpenAI
+from langchain_core.messages import HumanMessage, SystemMessage
+import random
+
+def create_ab_test_chat(test_variant: str = None):
+    """Create chat instance for A/B testing with appropriate tags"""
+    
+    if test_variant is None:
+        test_variant = random.choice(["variant-a", "variant-b"])
+    
+    return ChatOpenAI(
+        openai_api_base="http://localhost:4000",
+        model="gpt-4o",
+        temperature=0.7 if test_variant == "variant-a" else 0.9,  # Different temp for variants
+        extra_body={
+            "metadata": {
+                "tags": [
+                    "ab-test-experiment-1",
+                    f"variant-{test_variant}",
+                    "temperature-test",
+                    "user-experience"
+                ],
+                "experiment_id": "ab-test-001",
+                "variant": test_variant,
+                "test_group": "temperature-optimization"
+            }
+        }
+    )
+
+# Run A/B test
+variant_a_chat = create_ab_test_chat("variant-a")
+variant_b_chat = create_ab_test_chat("variant-b")
+
+test_message = [HumanMessage(content="Explain quantum computing in simple terms")]
+
+response_a = variant_a_chat.invoke(test_message)
+response_b = variant_b_chat.invoke(test_message)
+```
+
+### Tag Best Practices
+
+#### 1. **Consistent Naming Convention**
+```python
+# ✅ Good: Consistent, descriptive tags
+tags = ["production", "api-v2", "customer-support", "urgent"]
+
+# ❌ Avoid: Inconsistent or unclear tags
+tags = ["prod", "v2", "support", "urgent123"]
+```
+
+#### 2. **Hierarchical Tags**
+```python
+# ✅ Good: Hierarchical structure
+tags = ["env:production", "team:backend", "service:api", "priority:high"]
+
+# This allows for easy filtering and grouping
+```
+
+#### 3. **Include Context Information**
+```python
+extra_body={
+    "metadata": {
+        "tags": ["production", "user-onboarding"],
+        "user_id": "user-12345",
+        "session_id": "session-abc123",
+        "feature_flag": "new-onboarding-flow",
+        "environment": "production"
+    }
+}
+```
+
+#### 4. **Tag Categories**
+Consider organizing tags into categories:
+- **Environment**: `production`, `staging`, `development`
+- **Team/Service**: `backend`, `frontend`, `api`, `worker`
+- **Feature**: `authentication`, `payment`, `notification`
+- **Priority**: `critical`, `high`, `medium`, `low`
+- **User Type**: `premium`, `enterprise`, `free`
+
+### Using Tags with LiteLLM Proxy
+
+When using tags with LiteLLM Proxy, you can:
+
+1. **Filter requests** based on tags
+2. **Track costs** by tags in spend reports
+3. **Apply routing rules** based on tags
+4. **Monitor usage** with tag-based analytics
+
+#### Example Proxy Configuration with Tags
+
+```yaml
+# config.yaml
+model_list:
+  - model_name: gpt-4o
+    litellm_params:
+      model: gpt-4o
+      api_key: your-key
+
+# Tag-based routing rules
+tag_routing:
+  - tags: ["premium", "high-priority"]
+    models: ["gpt-4o", "claude-3-opus"]
+  - tags: ["standard"]
+    models: ["gpt-3.5-turbo", "claude-3-haiku"]
+```
+
+### Monitoring and Analytics
+
+Tags enable powerful analytics capabilities:
+
+```python
+# Example: Get spend reports by tags
+import requests
+
+response = requests.get(
+    "http://localhost:4000/global/spend/report",
+    headers={"Authorization": "Bearer sk-your-key"},
+    params={
+        "start_date": "2024-01-01",
+        "end_date": "2024-12-31",
+        "group_by": "tags"
+    }
+)
+
+spend_by_tags = response.json()
+```
+
+This documentation covers the essential patterns for using tags effectively with LangChain and LiteLLM, enabling better organization, tracking, and analytics of your LLM requests.