feat: init llm-proxy

README.md

@@ -0,0 +1,74 @@
+# LLM Proxy Server
+
+A simple OpenAI-compatible proxy server that forwards requests to any LLM endpoint with logging and cost tracking. The logs are stored in a PostgreSQL database. It's not possible to ignore the logging at the moment.
+
+## Configuration
+
+| Environment Variable | Description | Default Value |
+|----------------------|-------------|-----------------|
+| `PORT` | Server port | `3007` |
+| `UPSTREAM_URL` | Your LLM endpoint URL | `""` |
+| `DATABASE_URL` | PostgreSQL connection string for logging | `""` |
+| `DATABASE_TABLE` | Name of the table to store the logs | `"llm_proxy"` |
+
+### Cost Calculation
+
+The cost is calculated based on the model and the usage.
+
+You'll need to add the cost configuration for your models in the `cost.ts` file. The default cost configuration in the project (with sample values from `z.ai` models) is:
+
+```typescript
+export const MODEL_COSTS: Record<string, CostConfig> = {
+  "glm-4.5-air": { input: 0.2, cached: 0.03, output: 1.1 }, // cost per million prompt tokens (USD)
+  "glm-4.6": { input: 0.6, cached: 0.11, output: 2.2 }, // cost per million cached tokens (USD)
+  "default": { input: 0, cached: 0, output: 0 }, // default cost configuration
+};
+```
+
+You can add more models to the `MODEL_COSTS` object.
+
+## PostgreSQL Table Schema
+
+```sql
+CREATE TABLE IF NOT EXISTS <DATABASE_TABLE> (
+  timestamp TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
+  request_method VARCHAR(10) NOT NULL,
+  request_path VARCHAR(255) NOT NULL,
+  model VARCHAR(20) NOT NULL,
+  completion_tokens INTEGER,
+  prompt_tokens INTEGER,
+  total_tokens INTEGER,
+  cached_tokens INTEGER,
+  total_cost NUMERIC,
+  response_time INTEGER,
+  request_body JSONB,
+  response_body JSONB,
+  response_status INTEGER,
+  provider_url VARCHAR(500)
+);
+
+CREATE INDEX IF NOT EXISTS idx_<DATABASE_TABLE>_timestamp ON <DATABASE_TABLE> (timestamp);
+```
+
+## Usage
+
+The proxy works with any OpenAI-compatible endpoint. Just point your client to the proxy:
+
+```bash
+curl -X POST http://localhost:3007/chat/completions \
+  -H "Content-Type: application/json" \
+  -H "Authorization: Bearer your-api-key" \
+  -d '{
+    "model": "your-model",
+    "messages": [{"role": "user", "content": "Hello!"}]
+  }'
+```
+
+## Features
+
+- ✅ OpenAI-compatible API
+- ✅ Streaming support
+- ✅ PostgreSQL logging
+- ✅ Cost tracking
+- ✅ CORS enabled
+- ✅ Simple configuration - just set your endpoint URL