Include other response headers in SXG?

[twifkak]

nginx-sxg-module/ngx_http_sxg_filter_module.c

Lines 326 to 327 in 9d11d8a

	copy_response_header_to_sxg_header(req->pool, &req->headers_out.headers,
	&response.header) &&

and

nginx-sxg-module/ngx_http_sxg_filter_module.c

Lines 823 to 824 in 9d11d8a

	if (!copy_response_header_to_sxg_header(req->pool, &req->headers_out.headers,
	&ctx->response.header)) {

only include the "extra headers" from the ngx_http_headers_out_t. Can we add support for all the other headers, too?

[twifkak]

Also, expires is omitted in

nginx-sxg-module/ngx_http_sxg_filter_module.c

Lines 294 to 297 in 9d11d8a

	if (strncasecmp(kExpires, (char*)v[i].key.data, strlen(kExpires)) == 0) {
	/* SXG inner header does not require `expires` key */
	continue;
	}

Why is that?

[orisano]

Already, not only include the "extra headers".
headers_out has set by src/http/ngx_http_upstream.c.
https://github.com/nginx/nginx/blob/fa2f2e35082ba01a8aed026b34fc5246637f104e/src/http/ngx_http_upstream.c#L2713-L2853
these fields are for fast access.

[kumagi]

I cannot remember the reason why omitted expires header.
We should consider well about which inner header should be included or not.

[twifkak]

@orisano Ah, thanks for the correction.

@kumagi webpackager and amppackager may serve as inspiration. For instance, ampproject/amppackager#193 and ampproject/amppackager#260 contain some considerations of upstream headers. However, this module is different because the source of the response may not be an upstream HTTP server. If it's from a file or FastCGI, the gateway rules may not apply. I think the right place for such modifications is nginx proxy_pass; is it possible this is already happening?

[kumagi]

@twifkak OK, removing connection header would be reasonable for inner header, but I have no good idea about the others.