Proposal

Extend the GenericRandomErrorPlugin to enhance the handling of the retry-after response header. Currently, the initial value for retry-after is set globally for all responses in the plugin's configuration. This feature proposes supporting a syntax of @dynamic=initialvalue within the response header, enabling the initial retry-after value to be set on a per-response basis.

Motivation

• Allows greater flexibility and realism when simulating errors with varying backoff requirements.
• Developers can configure different endpoints to return different initial retry-after values, improving test coverage for clients handling these scenarios.

Acceptance Criteria

• The plugin should parse the @dynamic=initialvalue syntax from the retry-after response header configuration.
• If present, the initial retry-after value for that response should override the global default for that invocation.
• Documentation should be updated with usage examples.

Example

{
  "$schema": "https://raw.githubusercontent.com/dotnet/dev-proxy/main/schemas/v0.29.0/genericrandomerrorplugin.errorsfile.schema.json",
  "errors": [
    {
      "request": {
        "url": "https://models.github.ai/inference/chat/completions",
        "method": "POST"
      },
      "responses": [
        {          
          "statusCode": 429,
          "headers": [
            {
              "name": "Content-Type",
              "value": "application/json; charset=utf-8"
            },
            {
              "name": "Retry-After",
              "value": "@dynamic=17"
            }
          ],
          "body": {
            "error": {
              "code": "RateLimitReached",
              "message": "Rate limit of 15 per 60s exceeded for UserByModelByMinute. Please wait 17 seconds before retrying.",
              "details": "Rate limit of 15 per 60s exceeded for UserByModelByMinute. Please wait 17 seconds before retrying."
            }
          }
        }
      ]
    }
  ]
}

In this example, the initial retry-after value will be set to 17 for this response, regardless of the global plugin setting.