GZip compression with official nginx docker image

by Thomas VIAL

For a better experience, I wanted to improve the performance of this blog. I combined/minified css/js files, but I saw that these assets were not compressed.

# Call without gzip
➜  ~  curl http://tvi.al/assets/js/tvi.al.min.js\?v\=8419b36904 --silent --write-out "%{size_download}\n" --output /dev/null
119887

# Call with gzip
➜  ~  curl http://tvi.al/assets/js/tvi.al.min.js\?v\=8419b36904 --silent -H "Accept-Encoding: gzip,deflate" --write-out "%{size_download}\n" --output /dev/null
119887

The size remains the same.

It was strange because I worked with my configurations files before I move to docker.

I thought that the official nginx image was compiled without gzip module. But it is:

$ docker run nginx nginx -V
nginx version: nginx/1.9.0
built by gcc 4.9.2 (Debian 4.9.2-10)
built with OpenSSL 1.0.1k 8 Jan 2015
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --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-threads --with-stream --with-stream_ssl_module --with-mail --with-mail_ssl_module --with-file-aio --with-http_spdy_module --with-cc-opt='-g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2' --with-ld-opt='-Wl,-z,relro -Wl,--as-needed' --with-ipv6

As you can see, --with-http_gzip_static_module is here.

So where is the problem?

Well I found that adding gzip_http_version 1.0; to nginx.conf solves the problem (default value is 1.1).

# Call without gzip
➜  ~  curl http://tvi.al/assets/js/tvi.al.min.js\?v\=8419b36904 --silent --write-out "%{size_download}\n" --output /dev/null
119887

# Call with gzip
➜  ~  curl http://tvi.al/assets/js/tvi.al.min.js\?v\=8419b36904 --silent -H "Accept-Encoding: gzip,deflate" --write-out "%{size_download}\n" --output /dev/null
34441

As you can see, the asset is now gziped and lighter.