Varnish config file

default.vcl

backend default {
  .host = "127.0.0.1";
  .port = "80";
  .connect_timeout = 600s;
  .first_byte_timeout = 600s;
  .between_bytes_timeout = 600s;
}

acl purge {
  "localhost";
  "127.0.0.1";
}

sub vcl_recv {
  if (req.request == "GET" && req.url ~ "^/varnishcheck$") {
    error 200 "Varnish is Ready";
  }

  # Add a unique header containing the client address.
  set req.http.X-Forwarded-For = client.ip;

  if (req.request != "GET" &&
    req.request != "HEAD" &&
    req.request != "PUT" &&
    req.request != "POST" &&
    req.request != "TRACE" &&
    req.request != "OPTIONS" &&
    req.request != "PURGE" &&
    req.request != "DELETE") {
      # Non-RFC2616 or CONNECT which is weird.
      return (pipe);
  }

  # We only deal with GET, PURGE and HEAD by default.
  if (req.request != "GET" && req.request != "HEAD" && req.request != "PURGE") {
    return (pass);
  }

  # --- PURGE ---
  if (req.request == "PURGE") {
    # Check if the ip coresponds with the acl purge
    if (!client.ip ~ purge) {
      # Return error code 405 (Forbidden) when not
      error 405 "Not allowed.";
    }
    return (lookup);
  }

  # --- PASSTHROUGH ---

  # Always cache things with these extensions.
  if (req.url ~ "\.(js|css|jpg|jpeg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|swf)$") {
    unset req.http.cookie;
    return (lookup);
  }

  # Do not cache if HTTP authorized.
  if (req.http.Authorization) {
    return (pass);
  }

  # Skip the Varnish cache for install, update, and cron.
  if (req.url ~ "install\.php|update\.php|cron\.php") {
    return (pass);
  }

  # Skip the Varnish cache for Springboard standalone cron.
  if (req.url ~ "queue_processor_cron|fundraiser_cron") {
    return (pass);
  }

  # Pass server-status.
  if (req.url ~ ".*/server-status$") {
    return (pass);
  }

  # Support for Pressflow Cookie-Cache Bypass.
  if (req.http.cookie ~ "NO_CACHE") {
    return (pass);
  }

  # Force lookup if the request is a no-cache request from the client.
  if (req.http.Cache-Control ~ "no-cache") {
    return (pass);
  }

  # Don't check cache if Drupal SESSION is set.
  if (req.http.cookie ~ "SESS") {
    return (pass);
  }

  # We  "hide" the non-session cookies.
  if (req.http.cookie) {
    set req.http.X-Varnish-Cookie = req.http.cookie;
    unset req.http.cookie;
  }

  # --- MISC ---

  # Normalize the Accept-Encoding header
  # as per: http://varnish-cache.org/wiki/FAQ/Compression
  if (req.http.Accept-Encoding) {
    if (req.url ~ "\.(jpg|png|gif|gz|tgz|bz2|tbz|mp3|ogg)$") {
      # No point in compressing these.
      unset req.http.Accept-Encoding;
    }
    else if (req.http.Accept-Encoding ~ "gzip") {
      set req.http.Accept-Encoding = "gzip";
    }
    else if (req.http.Accept-Encoding ~ "deflate") {
      # Next, try deflate if it is supported.
      set req.http.Accept-Encoding = "deflate";
    }
    else {
      # Unknown or deflate algorithm.
      unset req.http.Accept-Encoding;
    }
  }

  # Let's have a little grace.
  set req.grace = 5m;

  return (lookup);
}

sub vcl_hash {
  if (req.http.cookie) {
    hash_data(req.http.cookie);
  }
}

# Strip any cookies before an image/js/css is inserted into cache.
sub vcl_fetch {
  set beresp.grace = 5m;

  # These status codes should always pass through and never cache.
  if (beresp.status == 503 || beresp.status == 500) {
    set beresp.http.X-Cacheable = "NO: obj.status";
    set beresp.http.X-Cacheable-status = beresp.status;
    return (hit_for_pass);
  }

  if (req.url ~ "\.(js|css|jpg|jpeg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|swf)(\?[a-z0-9]+)?$") {
    unset beresp.http.set-cookie;
  }
  else if (beresp.http.Cache-Control) {
    unset beresp.http.Expires;
  }

  if (beresp.status == 301) {
    set beresp.ttl = 1h;
    return(deliver);
  }

  # All tests passed, therefore item is cacheable
  set beresp.http.X-Cacheable = "YES";
}

# Set a header to track a cache HIT/MISS.
sub vcl_deliver {
  if (obj.hits > 0) {
    set resp.http.X-Varnish-Cache = "HIT";
    set resp.http.X-Varnish-Hits = obj.hits;
  }
  else {
    set resp.http.X-Varnish-Cache = "MISS";
  }
  # Set a header to track the webhead.
  set resp.http.X-Varnish-ID = server.identity;
}

sub vcl_hit {
  if (req.request == "PURGE") {
    purge;
    error 200 "Purged.";
  }
}

sub vcl_miss {
  if (req.http.X-Varnish-Cookie) {
    set bereq.http.cookie = req.http.X-Varnish-Cookie;
    unset bereq.http.X-Varnish-Cookie;
  }
  if (req.request == "PURGE") {
    purge;
    error 200 "Purged.";
  }
}

sub vcl_error {
  # Let's deliver a friendlier error page.
  set obj.http.Content-Type = "text/html; charset=utf-8";
  synthetic {"
  <?xml version="1.0" encoding="utf-8"?>
  <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
  <html>
    <head>
      <title>"} + obj.status + " " + obj.response + {"</title>
    </head>
    <body>
    <div id="page">
      <h1>Page Could Not Be Loaded</h1>
      <p>We're very sorry, but the page could not be loaded properly. This should be fixed very soon, and we apologize for any inconvenience.</p>
      <hr />
      <h4>Debug Info:</h4>
        <pre>Status: "} + obj.status + {"
Response: "} + obj.response + {"
XID: "} + req.xid + {"</pre>
      </div>
    </body>
   </html>
  "};
  return (deliver);
}

Needs to incorporate info from this: http://drupal.org/node/1054886

Thusly incorporated.