id summary reporter owner description type status priority milestone component version resolution keywords cc uname nginx_version
2660 SSI is included twice when empty response is loaded from proxy cache 0x4a616e@… "Nginx includes a stub for an SSI twice when an empty response response from the upstream is loaded from proxy cache and there is at least one other SSI.
Consider the following example:
{{{
test
I am a fallback
}}}
* The response of `/non_empty/` will be 200 OK with non-empty response body
* The response of `/empty/` will be 200 OK with empty response body (`Content-Length: 0`)
* The response of `/empty/` is cached in a local `proxy_cache`
Then, the first response will be
{{{
test
i am not empty
I am a fallback
}}}
and the second response (using the proxy_cache) will be
{{{
test
i am not empty
I am a fallback
I am a fallback
}}}
* Adding `wait=""yes""` to the include directives solves the issue.
* Removing the proxy_cache solves the issue.
The nginx debug log is attached. You can see that the stub is included two times.
{{{
2024/06/19 09:16:00 [debug] 7#7: *5 ssi stub output: ""/empty/?""
2024/06/19 09:16:00 [debug] 7#7: *5 ssi stub output: ""/empty/?""
}}}
The issue seems to be introduced with 1.23.4 and is still present in 1.27.0. Version 1.23.3 does not have this issue.
The following project shows a complete example of the issue https://github.com/0x4a616e/nginx_ssi_issue/" defect new major nginx-core 1.24.x ssi proxy_cache Linux 20c2e793c008 6.6.31-linuxkit #1 SMP PREEMPT_DYNAMIC Wed Jun 5 07:37:32 UTC 2024 x86_64 Linux "nginx version: nginx/1.24.0
built by gcc 12.2.1 20220924 (Alpine 12.2.1_git20220924-r4)
built with OpenSSL 3.0.7 1 Nov 2022 (running with OpenSSL 3.0.12 24 Oct 2023)
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --with-perl_modules_path=/usr/lib/perl5/vendor_perl --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-cc-opt='-Os -fomit-frame-pointer -g' --with-ld-opt=-Wl,--as-needed,-O1,--sort-common"