Langchain Deploy Integration

---
name: langchain-deploy-integration
description: |
  Deploy LangChain integrations to production environments.
  Use when deploying to cloud platforms, configuring containers,
  or setting up production infrastructure for LangChain apps.
  Trigger with phrases like "deploy langchain", "langchain production deploy",
  "langchain cloud run", "langchain docker", "langchain kubernetes".
allowed-tools: Read, Write, Edit, Bash(docker:*), Bash(gcloud:*)
version: 1.0.0
license: MIT
author: Jeremy Longshore <jeremy@intentsolutions.io>
---

# LangChain Deploy Integration

## Overview
Deploy LangChain applications to production using containers and cloud platforms with best practices for scaling and reliability.

## Prerequisites
- LangChain application ready for production
- Docker installed
- Cloud provider account (GCP, AWS, or Azure)
- API keys stored in secrets manager

## Instructions

### Step 1: Create Dockerfile
```dockerfile
# Dockerfile
FROM python:3.11-slim as builder

WORKDIR /app

# Install build dependencies
RUN apt-get update && apt-get install -y --no-install-recommends \
    build-essential \
    && rm -rf /var/lib/apt/lists/*

# Install Python dependencies
COPY requirements.txt .
RUN pip install --no-cache-dir --user -r requirements.txt

# Production stage
FROM python:3.11-slim

WORKDIR /app

# Copy installed packages from builder
COPY --from=builder /root/.local /root/.local
ENV PATH=/root/.local/bin:$PATH

# Copy application code
COPY src/ ./src/
COPY main.py .

# Create non-root user
RUN useradd --create-home appuser
USER appuser

# Health check
HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
    CMD python -c "import requests; requests.get('http://localhost:8080/health')"

EXPOSE 8080

CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8080"]
```

### Step 2: Create FastAPI Application
```python
# main.py
from fastapi import FastAPI, HTTPException
from pydantic import BaseModel
from contextlib import asynccontextmanager
import os

from langchain_openai import ChatOpenAI
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.output_parsers import StrOutputParser

# Initialize LLM on startup
llm = None
chain = None

@asynccontextmanager
async def lifespan(app: FastAPI):
    global llm, chain
    # Startup
    llm = ChatOpenAI(
        model=os.environ.get("MODEL_NAME", "gpt-4o-mini"),
        max_retries=3
    )
    prompt = ChatPromptTemplate.from_template("{input}")
    chain = prompt | llm | StrOutputParser()
    yield
    # Shutdown
    pass

app = FastAPI(lifespan=lifespan)

class ChatRequest(BaseModel):
    input: str
    max_tokens: int = 1000

class ChatResponse(BaseModel):
    response: str

@app.get("/health")
async def health():
    return {"status": "healthy", "model": os.environ.get("MODEL_NAME")}

@app.post("/chat", response_model=ChatResponse)
async def chat(request: ChatRequest):
    try:
        response = await chain.ainvoke({"input": request.input})
        return ChatResponse(response=response)
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))
```

### Step 3: Deploy to Google Cloud Run
```bash
# Build and push container
gcloud builds submit --tag gcr.io/PROJECT_ID/langchain-api

# Deploy to Cloud Run
gcloud run deploy langchain-api \
    --image gcr.io/PROJECT_ID/langchain-api \
    --platform managed \
    --region us-central1 \
    --allow-unauthenticated \
    --set-secrets=OPENAI_API_KEY=openai-api-key:latest \
    --memory 1Gi \
    --cpu 2 \
    --min-instances 1 \
    --max-instances 10 \
    --concurrency 80
```

### Step 4: Kubernetes Deployment
```yaml
# k8s/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: langchain-api
spec:
  replicas: 3
  selector:
    matchLabels:
      app: langchain-api
  template:
    metadata:
      labels:
        app: langchain-api
    spec:
      containers:
      - name: langchain-api
        image: gcr.io/PROJECT_ID/langchain-api:latest
        ports:
        - containerPort: 8080
        env:
        - name: OPENAI_API_KEY
          valueFrom:
            secretKeyRef:
              name: langchain-secrets
              key: openai-api-key
        - name: MODEL_NAME
          value: "gpt-4o-mini"
        resources:
          requests:
            memory: "512Mi"
            cpu: "500m"
          limits:
            memory: "1Gi"
            cpu: "1000m"
        readinessProbe:
          httpGet:
            path: /health
            port: 8080
          initialDelaySeconds: 5
          periodSeconds: 10
        livenessProbe:
          httpGet:
            path: /health
            port: 8080
          initialDelaySeconds: 15
          periodSeconds: 20
---
apiVersion: v1
kind: Service
metadata:
  name: langchain-api
spec:
  selector:
    app: langchain-api
  ports:
  - port: 80
    targetPort: 8080
  type: LoadBalancer
```

### Step 5: Configure Autoscaling
```yaml
# k8s/hpa.yaml
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: langchain-api-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: langchain-api
  minReplicas: 2
  maxReplicas: 20
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 70
  - type: Resource
    resource:
      name: memory
      target:
        type: Utilization
        averageUtilization: 80
```

## Output
- Production-ready Dockerfile with multi-stage build
- FastAPI application with health checks
- Cloud Run deployment configuration
- Kubernetes manifests with autoscaling

## Examples

### Local Testing
```bash
# Build locally
docker build -t langchain-api .

# Run with env file
docker run -p 8080:8080 --env-file .env langchain-api

# Test endpoint
curl -X POST http://localhost:8080/chat \
    -H "Content-Type: application/json" \
    -d '{"input": "Hello!"}'
```

### AWS Deployment (ECS)
```bash
# Create ECR repository
aws ecr create-repository --repository-name langchain-api

# Push image
docker tag langchain-api:latest ACCOUNT.dkr.ecr.REGION.amazonaws.com/langchain-api:latest
docker push ACCOUNT.dkr.ecr.REGION.amazonaws.com/langchain-api:latest

# Deploy with Copilot
copilot deploy
```

## Error Handling
| Error | Cause | Solution |
|-------|-------|----------|
| Container Crash | Missing env vars | Check secrets injection |
| Cold Start Timeout | LLM init slow | Use min-instances > 0 |
| Memory OOM | Large context | Increase memory limits |
| Connection Refused | Port mismatch | Verify EXPOSE and --port match |

## Resources
- [Cloud Run Documentation](https://cloud.google.com/run/docs)
- [Kubernetes Best Practices](https://kubernetes.io/docs/concepts/configuration/overview/)
- [Docker Multi-stage Builds](https://docs.docker.com/build/building/multi-stage/)

## Next Steps
Configure `langchain-observability` for production monitoring.