The list of LLM models that appear in Opik's dropdowns (Playground, LLM-as-Judge, Automation Rules, Optimization Studio) is served by the backend from a YAML registry. The registry is composed from up to three sources, merged in this order:

1. **Classpath defaults** — `llm-models-default.yaml` shipped inside the backend JAR. Always loaded. This is the source every deployment sees out of the box.
2. **Remote CDN YAML** — **opt-in**. When enabled, the backend fetches a YAML from a URL you configure and refreshes it on a schedule. Self-hosted deployments are not required to use this; it's primarily for operators who want to pick up new models between Opik releases without redeploying.
3. **Local override YAML** — optional. A YAML file you mount into the backend container; its entries override or extend the defaults and the remote content.

This page describes how to configure these sources for self-hosted deployments.

## Environment variables

All configuration is via env vars on the opik-backend container.

| Variable                                      | Default                   | Purpose                                                                   |
| --------------------------------------------- | ------------------------- | ------------------------------------------------------------------------- |
| `LLM_MODEL_REGISTRY_DEFAULT_RESOURCE`         | `llm-models-default.yaml` | Classpath resource name. Rarely changed.                                  |
| `LLM_MODEL_REGISTRY_REMOTE_ENABLED`           | `false`                   | Set `true` to enable the optional remote CDN fetch.                       |
| `LLM_MODEL_REGISTRY_REMOTE_URL`               | empty                     | URL (http/https) of the remote YAML. Required when `REMOTE_ENABLED=true`. |
| `LLM_MODEL_REGISTRY_REFRESH_INTERVAL_SECONDS` | `300`                     | How often to re-fetch the remote YAML.                                    |
| `LLM_MODEL_REGISTRY_LOCAL_OVERRIDE_PATH`      | empty                     | Absolute path to a local override YAML inside the container.              |

## YAML schema

```yaml
openai:
  - id: "gpt-4o"
    label: "GPT 4o"
    structuredOutput: true
    reasoning: false
anthropic:
  - id: "claude-opus-4-7"
    label: "Claude Opus 4.7"
    reasoning: false
vertex-ai:
  - id: "gemini-2.5-pro"
    qualifiedName: "vertex_ai/gemini-2.5-pro"
    label: "Gemini 2.5 Pro"
    structuredOutput: true
```

Fields:

- `id` (required) — the model identifier used at inference time.
- `qualifiedName` (optional) — disambiguates models that exist under multiple providers (e.g. Gemini via Vertex AI vs. the Gemini API directly). Used as the routing key when set.
- `label` (optional) — the human-readable name shown in dropdowns. Falls back to `id` when omitted.
- `structuredOutput` (optional, default `false`) — whether the model supports JSON schema / tool-calling structured output mode.
- `reasoning` (optional, default `false`) — whether the model is a reasoning model (enforces temperature = 1.0 and unlocks reasoning-effort parameters in the UI).

## Merge behavior

Models are keyed by `id` across every provider. `qualifiedName` is used for routing lookups (to disambiguate `gemini-2.5-pro` under the Gemini direct API vs. Vertex AI), but override deduplication always uses `id`. When a merge happens:

- **Add**: an `id` not present in lower layers is appended to that provider's list.
- **Override**: an `id` that matches a lower layer replaces the full definition. Partial overrides are not supported — supply all fields you want on the final model.
- **Remove**: not currently supported. Contact support if you need to hide a default model entirely.

## Configuration scenarios

### Default behaviour

Leave the defaults in place. The backend serves the classpath `llm-models-default.yaml` shipped with your Opik release — no outbound traffic, no extra configuration. Upgrade Opik to pick up new models.

### Enable the remote CDN fetch (optional)

If you want new models to reach your running deployment between Opik releases — e.g. if you run long-lived stacks on an extended upgrade cadence and want provider-side additions to land automatically — point the backend at a remote YAML:

```
LLM_MODEL_REGISTRY_REMOTE_ENABLED=true
LLM_MODEL_REGISTRY_REMOTE_URL=https://your-cdn.example.com/opik/llm-models-default.yaml
LLM_MODEL_REGISTRY_REFRESH_INTERVAL_SECONDS=3600
```

Comet SaaS uses `https://cdn.comet.ml/opik/llm-models-default.yaml`, regenerated daily by the Opik sync workflow — you can either mirror that content on your own CDN or point directly at it if your policies allow.

Remote fetch failures are logged but non-fatal: the backend keeps serving the last successful registry (or the classpath defaults if the first fetch fails), so enabling the remote tier never risks losing model routing.

### Add a private fine-tuned model (Docker Compose)

Create `/etc/opik/my-models-override.yaml` on the host:

```yaml
openai:
  - id: "ft:gpt-4o-2024-08-06:my-org::abc123"
    label: "Our Fine-Tuned GPT-4o"
    structuredOutput: true
```

Mount it into the backend container and set the path:

```yaml
# docker-compose.override.yaml
services:
  backend:
    volumes:
      - /etc/opik/my-models-override.yaml:/opt/opik/models-override.yaml:ro
    environment:
      LLM_MODEL_REGISTRY_LOCAL_OVERRIDE_PATH: /opt/opik/models-override.yaml
```

### Add a private fine-tuned model (Kubernetes / Helm)

Create a ConfigMap with your override YAML:

```bash
kubectl create configmap opik-llm-models-override \
  --from-file=models-override.yaml=/path/to/models-override.yaml
```

Mount it in the backend Deployment by extending your Helm values:

```yaml
# values.yaml overrides
component:
  backend:
    env:
      LLM_MODEL_REGISTRY_LOCAL_OVERRIDE_PATH: "/etc/opik/models-override.yaml"
    volumes:
      - name: llm-models-override
        configMap:
          name: opik-llm-models-override
    volumeMounts:
      - name: llm-models-override
        mountPath: /etc/opik/models-override.yaml
        subPath: models-override.yaml
        readOnly: true
```

## Verification

After restart, check that your model appears:

```bash
curl -s https://your-opik/api/v1/private/llm/models | jq '.openai[] | select(.id | contains("ft:"))'
```

The same list appears in the UI dropdowns within seconds of a browser refresh.

## Failure modes

| What fails                              | What happens                                   |
| --------------------------------------- | ---------------------------------------------- |
| Remote CDN fetch at startup             | Logged; registry uses classpath defaults only. |
| Remote CDN fetch on scheduled refresh   | Logged; previous in-memory registry retained.  |
| Override YAML malformed                 | Logged; registry uses classpath + remote only. |
| Override YAML path set but file missing | Silently ignored (defaults + remote used).     |

## Related pages

- [.NET](./net-index.md)
- [Administration](./administration-index.md)
- [AI Coding Assistants](./ai-coding-assistants-index.md)
- [Changelog](../changelog.md)
- [Configuration](./configuration-index.md)
- [Contributing](./contributing-index.md)
- [Development](./development-index.md)
- [Evaluation](./evaluation-index.md)
- [Getting Started](./getting-started-index.md)
- [Guardrails](./guardrails-index.md)

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