id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
1249	Blocking STALE requests using proxy_cache_background_update on Docker	rdngr@…		"When running nginx within a Docker container operating in bridged networking mode the proxy_cache_background_update feature does not always work as intended. Certain requests, particularly requests with large response bodies, will cause nginx to wait for the server to reply with a new version instead of immediately sending the cached resource.

All requests where background updates become blocking log the following:

{{{
2017/04/14 08:13:46 [debug] 7#7: *3 writev() not ready (11: Resource temporarily unavailable)
}}}

Switching the Docker container to host networking mode seems to completely resolve the issue.

The issue has been replicated on three different machines (two physical running Arch Linux and one virtual running CentOS 7), with three different Docker versions: 1.12.6, 17.03.0, and 17.04.0.

The behavior is identical on both Ubuntu and Alpine base Docker images.

Scripts and configuration for reproducing the issue are available at [https://github.com/rdngr/nginx-background-issue]"	defect	closed	minor		nginx-core	1.11.x	fixed			Linux 4a7e76772df1 4.10.8-1-ARCH #1 SMP PREEMPT Fri Mar 31 16:50:19 CEST 2017 x86_64 Linux	"nginx version: nginx/1.11.13
built by gcc 6.2.1 20160822 (Alpine 6.2.1)
built with OpenSSL 1.0.2k  26 Jan 2017
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 --user=nginx --group=nginx --with-http_ssl_module --with-http_realip_module --with-http_addition_module --with-http_sub_module --with-http_dav_module --with-http_flv_module --with-http_mp4_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_random_index_module --with-http_secure_link_module --with-http_stub_status_module --with-http_auth_request_module --with-http_xslt_module=dynamic --with-http_image_filter_module=dynamic --with-http_geoip_module=dynamic --with-http_perl_module=dynamic --with-threads --with-stream --with-stream_ssl_module --with-stream_ssl_preread_module --with-stream_realip_module --with-stream_geoip_module=dynamic --with-http_slice_module --with-mail --with-mail_ssl_module --with-compat --with-file-aio --with-http_v2_module --with-debug"