> ## 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 Block

> Configuring the egress path and query parameters.

The `upstream` block handles rewriting the outgoing HTTP Path and Query Parameters before ONR dispatches the request to the upstream target.

## Path Mutation

You can completely replace the original request path using `set_path`.

```nginx theme={null}
upstream {
  set_path "/v1/chat/completions";
}
```

This ensures that regardless of whether a user calls `/v1/chat/completions` or `/v1/messages`, the upstream provider always sees the path defined by `set_path`.

## Query Parameter Operations

You can inject, override, or delete specific URL query parameters before dispatch.

### Setting/Modifying Queries

```nginx theme={null}
upstream {
  set_query "api-version" "2024-10-01";
  set_query stream "true";
  
  # Using built-in variables (NO QUOTES for variables):
  set_query key $channel.key;
}
```

*Note: Using `$channel.key` without quotes evaluates the variable dynamically. Specifying `"$channel.key"` inside quotes treats it as a literal string.*

### Deleting Queries

```nginx theme={null}
upstream {
  del_query "foo";
  del_query bar;
}
```

> **Execution Order**: When handling query parameters, ONR always executes all `del_query` directives *first*, followed by the `set_query` directives.