Serving WEBP with nginx conditionally.

nginx-webp-sample.conf

user www-data;

http {

  ##
  # Basic Settings
  ##

  sendfile on;
  tcp_nopush on;
  tcp_nodelay on;

  # IMPORTANT!!! Make sure that mime.types below lists WebP like that:
  # image/webp webp;
  include /etc/nginx/mime.types;
  default_type application/octet-stream;

  gzip on;
  gzip_disable "msie6";

  ##
  # Conditional variables
  ##
  
  map $http_accept $webp_suffix {
    default   "";
    "~*webp"  ".webp";
  }

  ##
  # Minimal server
  ##
  
  server {
    listen 80 default_server;
    listen [::]:80 default_server ipv6only=on;

    root /usr/share/nginx/html;
    index index.html;

    # Make site accessible from http://localhost/ or whatever you like
    server_name localhost;

    location ~* ^/images/.+\.(png|jpg)$ {
      root /home/www-data;
      add_header Vary Accept;
      try_files $uri$webp_suffix $uri =404;
    }
  }
}

This sample config is copied from grunt-tight-sprite's Recipe: serve WebP with nginx conditionally.

The corresponding blog post.

Thanks for both the gist and the blog post. They were really helpful.

One note: as far as I can tell, this can be simplified a bit. I did the following:

1. Removed the map directive entirely
2. Re-wrote try_files like this: try_files "${uri}.webp" $uri =404;

So now we're just doing a simple string interpolation instead of a map lookup.

This is convenient, because all of the relevant configs can now be placed within the server block. (Previously, I got errors when I deviated from what you did here and tried to put the map directive in the server block.) This might make it possible to touch fewer nginx config files than would otherwise be necessary.

It's possible that I'm overlooking something here, but as best as I can tell, this all works OK.