# response-contains-header

Requires that response objects with specific HTTP status codes or ranges contain specified response headers.

| OAS | Compatibility |
|  --- | --- |
| 2.0 | ✅ |
| 3.0 | ✅ |
| 3.1 | ✅ |


## API design principles

In some cases, it is important to design an API so that it consistently returns specific properties in responses. A common example is to return pagination headers for collections. This rule helps achieve the desired consistency across all or some responses in an API.

## Configuration

| Option | Type | Description |
|  --- | --- | --- |
| severity | string | **REQUIRED.** Possible values: `off`, `warn`, `error`. |
| names | Map (HTTP response code or range, [string]) | **REQUIRED.** For a given HTTP response code or range, the corresponding list of expected HTTP response headers. |


An example configuration:


```yaml
rules:
  response-contains-header:
    severity: error
    names:
      2XX:
        - x-request-id
        - x-correlation-id
      '400':
        - Content-Length
        - x-correlation-id
```

## Examples

Given this configuration:


```yaml
rules:
  response-contains-header:
    severity: error
    names:
      2XX:
        - x-request-id
        - x-correlation-id
      '400':
        - Content-Length
        - x-correlation-id
```

Example of an **incorrect** response:


```yaml
paths:
  /customers/{id}:
    post:
      responses:
        '200':
          description: OK
          headers:
            x-request-id:
              description: The request ID returned in the response.
              schema:
                type: string
```

Example of a **correct** response:


```yaml
paths:
  /customers/{id}:
    post:
      responses:
        '200':
          description: OK
          headers:
            x-request-id:
              description: The request ID returned in the response.
              schema:
                type: string
            x-correlation-id:
              description: The correlation ID for log audit purposes.
              schema:
                type: string
```

## Related rules

- [response-contains-property](/docs/cli/rules/oas/response-contains-property)
- [response-mime-type](/docs/cli/rules/oas/response-mime-type)
- [configurable rules](/docs/cli/rules/configurable-rules)


## Resources

- [Rule source](https://github.com/Redocly/redocly-cli/blob/main/packages/core/src/rules/common/response-contains-header.ts)
- [Response docs](https://redocly.com/docs/openapi-visual-reference/response/)