Detect image format webp support.

gistfile1.txt

worker_processes 1;

events {
  worker_connections 1024;
}

http {
  include mime.types;
  default_type  application/octet-stream;

  #
  # < regular Nginx configuration here >
  #

  # For a hands-on explanation of using Accept negotiation, see:
  # http://www.igvita.com/2013/05/01/deploying-webp-via-accept-content-negotiation/

  # if proxying to another backend and using nginx as cache
  proxy_cache_path  /tmp/cache levels=1:2 keys_zone=my-cache:8m max_size=1000m inactive=600m;
  proxy_temp_path /tmp/cache/tmp;

  server {
    listen       8081;
    server_name  localhost;

    # check Accept header for webp, check if .webp is on disk
    if ($http_accept ~* "webp")    { set $webp_accept "true"; }
    if (-f $request_filename.webp) { set $webp_local "true";  }

    location / {
      # if WebP variant is available, serve Vary
      if ($webp_local = "true") {
        add_header Vary Accept;
      }

      # if WebP is supported by client, serve it
      if ($webp_accept = "true") {
        rewrite (.*) $1.webp break;
      }
    }

    # if proxying to another backend and using nginx as cache
    proxy_cache_key $scheme$proxy_host$request_uri$webp_local$webp_accept;

    location /proxy {
      # Pass WebP support header to backend
      proxy_set_header  WebP  $webp;
      proxy_pass http://127.0.0.1:8080;
      proxy_cache my-cache;
    }
  }
}