This file is a sample VCL for Varnish 4.0. It will be used a back-end Plone. And support purge.

sample.v4.vcl

#
# This is an example VCL file for Varnish.
#
# It does not do anything by default, delegating control to the
# builtin VCL. The builtin VCL is called when there is no explicit
# return statement.
#
# See the VCL chapters in the Users Guide at https://www.varnish-cache.org/docs/
# and http://varnish-cache.org/trac/wiki/VCLExamples for more examples.

# Marker to tell the VCL compiler that this VCL has been adapted to the
# new 4.0 format.
vcl 4.0;

import std;
import directors;

# Default backend definition. Set this to point to your content server.
backend ap1 {
  .host = "127.0.0.1";
  .port = "8080";
  .first_byte_timeout = 200s;
  .probe = {
         .url = "/";
         .interval = 5s;
         .timeout = 1 s;
         .window = 5;
         .threshold = 3;
         .initial = 1;
  }
}
backend ap2 {
  .host = "127.0.0.1";
  .port = "8081";
  .first_byte_timeout = 200s;
  .probe = {
         .url = "/";
         .interval = 5s;
         .timeout = 1 s;
         .window = 5;
         .threshold = 3;
         .initial = 1;
  }
}
acl purge_ip {
    "localhost";
    "127.0.0.1";
    // ""
}

sub vcl_init{
    new ws = directors.random();
    ws.add_backend(ap1, 1.0);
    ws.add_backend(ap2, 1.0);
}


sub vcl_recv {
    # Happens before we check if we have this in cache already.
    #
    # Typically you clean up the request here, removing cookies you don't need,
    # rewriting the request, etc.

#     std.log("vcl recv: "+req.request);

    if (req.restarts == 0) {
      if (req.http.x-forwarded-for) {
          set req.http.X-Forwarded-For =
          req.http.X-Forwarded-For + ", " + client.ip;
      } else {
          set req.http.X-Forwarded-For = client.ip;
      }
    }
    set req.backend_hint = ws.backend();
    if (req.method != "GET" &&
      req.method != "HEAD" &&
      req.method != "PUT" &&
      req.method != "POST" &&
      req.method != "TRACE" &&
      req.method != "OPTIONS" &&
      req.method != "PURGE" &&
      req.method != "DELETE") {
        /* Non-RFC2616 or CONNECT which is weird. */
        return (pipe);
    }
    if (req.method == "PURGE") {
         if (!client.ip ~ purge_ip) {
             #return(synth(405, "Not Found"));
             return(synth(403, "Not allowed"));
         }
         return (purge);
    }
    if (req.method != "GET" && req.method != "HEAD") {
        /* We only deal with GET and HEAD by default */
        return (pipe);
    }
    if (req.url ~ "\.(jpe?g|png|gif|pdf|gz|tgz|bz2|tbz|tar|zip|tiff|tif)$" || req.url ~ "/(image|(image_(?:[^/]|(?!view.*).+)))$") {
        return (hash);
    }
    if (req.url ~ "\.(svg|swf|ico|mp3|mp4|m4a|ogg|mov|avi|wmv|flv)$") {
        return (hash);
    }
    if (req.url ~ "\.(xls|vsd|doc|ppt|pps|vsd|doc|ppt|pps|xls|pdf|sxw|rar|odc|odb|odf|odg|odi|odp|ods|odt|sxc|sxd|sxi|sxw|dmg|torrent|deb|msi|iso|rpm)$") {
        return (hash);
    }
    if (req.url ~ "\.(css|js)$") {
        return (hash);
    }
    if (req.http.Authorization || req.http.Cookie ~ "(^|; )(__ac=|_ZopeId=)") {
        /* Not cacheable by default */
        return (pipe);
    }
    return (hash);
}


sub vcl_hash {
    hash_data(req.url);
    #if (req.http.host) {
    #    hash_data(req.http.host);
    #} else {
    #    hash_data(server.ip);
    #}
    return (lookup);
}

sub vcl_backend_response {
    # Happens after we have read the response headers from the backend.
    #
    # Here you clean the response headers, removing silly Set-Cookie headers
    # and other mistakes your backend does.
    if (beresp.ttl <= 0s ||
        beresp.http.Set-Cookie ||
        beresp.http.Vary == "*") {
        /*
         * Mark as "Hit-For-Pass" for the next 60 minutes - 24 hours
         */
        if (bereq.url ~ "\.(jpe?g|png|gif|pdf|gz|tgz|bz2|tbz|tar|zip|tiff|tif)$" || bereq.url ~ "/(image|(image_(?:[^/]|(?!view.*).+)))$") {
            set beresp.ttl = std.duration(beresp.http.age+"s",0s) + 6h;
        } elseif (bereq.url ~ "\.(svg|swf|ico|mp3|mp4|m4a|ogg|mov|avi|wmv|flv)$") {
            set beresp.ttl = std.duration(beresp.http.age+"s",0s) + 6h;
        } elseif (bereq.url ~ "\.(xls|vsd|doc|ppt|pps|vsd|doc|ppt|pps|xls|pdf|sxw|rar|odc|odb|odf|odg|odi|odp|ods|odt|sxc|sxd|sxi|sxw|dmg|torrent|deb|msi|iso|rpm)$") {
            set beresp.ttl = std.duration(beresp.http.age+"s",0s) + 6h;
        } elseif (bereq.url ~ "\.(css|js)$") {
            set beresp.ttl = std.duration(beresp.http.age+"s",0s) + 24h;
        } else {
            set beresp.ttl = std.duration(beresp.http.age+"s",0s) + 1h;
        }
    }
    return (deliver);
}

sub vcl_deliver {
    # Happens when we have all the pieces we need, and are about to send the
    # response to the client.
    #
    # You can do accounting or modifying the final object here.
}

sub vcl_synth {
    set resp.http.Content-Type = "text/html; charset=utf-8";
    set resp.http.Retry-After = "5";
    synthetic ("Error");
    return (deliver);
}

Hi,

After applying this vcl configuration in my varnish setup my website theme got disturbed in Firefox and IE. In google chrome it was working fine. Can you please let me know the issue?

Thanks,
Ajay