Enabling and testing SPDY support on Nginx

nginx_ssl_spdy

Enabling SPDY is pretty straightforward, all we need to do is to add the spdy parameter in the listen directives :

listen 443 ssl spdy;
listen [::]:443 ipv6only=on ssl spdy;

Header compression level is customizable using the spdy_headers_comp directive, for example :

spdy_headers_comp 1;

Check the SPDY module documentation for more details.

We can now test if SPDY is correctly enabled by displaying SPDY related embedded variables using the ngx_echo module :

location /spdy
{
    echo $spdy;
    echo $spdy_request_priority;
}

Accessing the /spdy URL endpoint using a SPDY enabled browser should display the protocol version (SPDY/2 at the time of writing) along with the request priority.

When accessing the URL using Firefox, the following values are displayed :

2
1

When accessing the URL using Chrome, the following values are displayed :

2
0

According to the protocol drafts, stream priority in SPDY/2 ranges from 0 (lowest priority) to 3 (highest priority), whereas in SPDY/3 it ranges from 0 (highest priority) to 7 (lowest priority).