> ## Documentation Index
> Fetch the complete documentation index at: https://onr.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Upstream Config Block

> Setting the base destination.

The `upstream_config` block defines the root target coordinate of the LLM provider.

## Syntax

```nginx theme={null}
upstream_config {
  base_url = "https://api.example.com";
}
```

### Directives

* `base_url`: (Required) Must be a fixed string literal defining the root domain.

> **Dynamic Override**: If the channel/provider key passing through ONR at runtime defines a `base_url` override, it will take precedence over this default value. Otherwise, this default is used.