Modifying request HTTP headers based on the content of request body

[huang195]

I see the following comments in all the functions to manipulate request headers:

// ReplaceHttpRequestHeaders is used for replacing HTTP request headers
// with given headers. Only available during
// types.HttpContext.OnHttpRequestHeaders.
func ReplaceHttpRequestHeaders(headers [][2]string) error {
    return setMap(internal.MapTypeHttpRequestHeaders, headers)
}

that they are only available during OnHttpRequestHeaders(). However, I'd like to inspect of the body of the request in OnHttpRequestBody(), and then conditionally modify the request headers. Is this not possible today? Or is there a coding pattern that could help with my situation?

[leonm1]

Hi @huang195, right now, the Proxy-Wasm spec does not allow modifying headers during body callbacks because it only supports ActionPause and ActionContinue as return values from OnHttpRequestHeaders. ActionContinue will send the headers to the upstream (therefore they can't be modified), while ActionPause will not forward the headers but will prevent the body callbacks from being called.

The relevant issue in the Proxy-Wasm spec is proxy-wasm/spec#63, which is planned for fixing in v0.3.0.

[huang195]

Thanks @leonm1 for the heads up on the open issue. Is there any time estimate on when v0.3.0 will be released?