Connecting to OSS Models

LangDB AI Gateway supports connecting to open-source models through providers like Ollama and vLLM. This allows you to use locally hosted models while maintaining the same OpenAI-compatible API interface.

Configuration

To use Ollama or vLLM, you need to provide a list of models with their endpoints. By default, ai-gateway loads models from ~/.langdb/models.yaml. You can define your models there in the following format:

- model: gpt-oss
  model_provider: ollama
  inference_provider:
    provider: ollama
    model_name: gpt-oss
    endpoint: https://my-ollama-server.localhost
  price:
    per_input_token: 0.0
    per_output_token: 0.0
  input_formats:
  - text
  output_formats:
  - text
  limits:
    max_context_size: 128000
  capabilities: ['tools']
  type: completions
  description: OpenAI's open-weight models designed for powerful reasoning, agentic tasks, and versatile developer use cases.

Configuration Fields

Field	Description	Required
model	The model identifier used in API requests	Yes
model_provider	The provider type (e.g., ollama, vllm)	Yes
inference_provider	Provider-specific configuration	Yes
price	Token pricing (set to 0.0 for local models)	Yes
input_formats	Supported input formats	Yes
output_formats	Supported output formats	Yes
limits	Model limitations (context size, etc.)	Yes
capabilities	Model capabilities array (e.g., ['tools'] for function calling)	Yes
type	Model type (e.g., completions)	Yes
description	Human-readable model description	Yes

Example Usage

Once configured, you can use your OSS models through the standard OpenAI-compatible API:

curl http://localhost:8080/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-oss",
    "messages": [{"role": "user", "content": "What is the capital of France?"}]
  }'

Supported Providers

Ollama

• Provider: ollama
• Endpoint: URL to your Ollama server
• Model Name: The model name as configured in Ollama

vLLM

• Provider: vllm
• Endpoint: URL to your vLLM server
• Model Name: The model name as configured in vLLM

Best Practices

1. Local Development: Use localhost or 127.0.0.1 for local Ollama/vLLM instances
2. Production: Use proper domain names or IP addresses for remote instances
3. Security: Ensure your OSS model endpoints are properly secured
4. Performance: Consider the network latency between ai-gateway and your model servers
5. Monitoring: Use the observability features to monitor OSS model performance