Varnish 3 - VCL

default.vcl

# The initial was for Varnish 2.1, this has been updated for Varnish 3.
# The upgrade changes were based on the docs here:
# https://www.varnish-cache.org/docs/3.0/installation/upgrade.html
# https://www.varnish-cache.org/docs/2.1/tutorial/vcl.html
# https://www.varnish-cache.org/trac/wiki/VCLExamples

# Summary
# 1. Varnish will poll the backend at /health_check to make sure it is
#    healthy. If the backend goes down, varnish will server stale content
#    from the cache for up to 1 hour.
# 2. Varnish will pass X-Forwarded-For headers through to the backend
# 3. Varnish will remove cookies from urls that match static content file
#    extensions (jpg, gif, ...)
# 4. Varnish will normalize the Accept-Encoding header
# 5. Varnish will respect the Cache-Control header, even when a Set-Cookie
#    header accompanies it from the backend. For example,
#    `Cache-Control: no-cache` will not get stored in Varnish and
#    `Cache-Control: max-age=600` will.
# 6. Varnish will add a X-Varnish-Cache header to aid in debugging

backend default {
  .host = "127.0.0.1";
  .port = "8080";
  .connect_timeout = 600s;
  .first_byte_timeout = 600s;
  .between_bytes_timeout = 600s;
}

# NOTE: vcl_recv is called at the beginning of a request, after the complete
# request has been received and parsed. Its purpose is to decide whether or not
# to serve the request, how to do it, and, if applicable, which backend to use.
sub vcl_recv {

   set req.grace = 1h;

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

  # Don't cache POST, PUT, or DELETE requests
  if (req.request == "POST" || req.request == "PUT" || req.request == "DELETE") {
    return(pass);
  }

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

  # 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);
  }

  # Skip the Varnish cache for logged users.
  if (req.url ~ "dashboard|settings") {
    return (pass);
  }

  # Strip cookies from static content
  if (req.request == "GET" && req.url ~ "\.(png|gif|jpg|swf|css|js)$") {
    unset req.http.cookie;
  }

  # We will try to retrieve every request from the cache. There will be no
  # intelligence on the varnish side to determine whether to look or not look
  # at the cache.
  
  return(lookup);
}

sub vcl_pipe {
  # Note that only the first request to the backend will have
  # X-Forwarded-For set.  If you use X-Forwarded-For and want to
  # have it set for all requests, make sure to have:
  # set bereq.http.connection = "close";
  # here.  It is not set by default as it might break some broken web
  # applications, like IIS with NTLM authentication.

  set bereq.http.connection = "close";
  return(pipe);
}

# NOTE: vcl_fetch is called after a document has been successfully retrieved
# from the backend. Normal tasks her are to alter the response headers, trigger
# ESI processing, try alternate backend servers in case the request failed.

sub vcl_fetch {
  if (beresp.status == 200) {
    set beresp.ttl = 1h;
    return (deliver);
  }

  if (beresp.ttl <= 0s ||
      beresp.http.set-cookie ||
      beresp.http.Vary == "*") {
        set beresp.ttl = 120s;
        return (hit_for_pass);
  }

  if (beresp.status != 200) {
    set beresp.ttl = 30s;
  }

  # If header specifies "no-cache", don't cache.
  if (
    beresp.http.Pragma        ~ "no-cache" ||
    beresp.http.Cache-Control ~ "no-cache" ||
    beresp.http.Cache-Control ~ "private"
  ) {
    return(hit_for_pass);
  }

  # Do not deliver into cache otherwise.
  return(deliver);
}

sub vcl_error {
  if (obj.status >= 500 && obj.status <= 505) {
    set obj.grace = 1h;
    return(restart);
  }

  return (deliver);
}

sub vcl_deliver {
  # The below provides custom headers to indicate whether the response came from
  # varnish cache or directly from the app.
  if (obj.hits > 0) {
    set resp.http.X-Varnish-Cache = "HIT";
    set resp.http.X-Cache-Hits = obj.hits;
  } else {
    set resp.http.X-Varnish-Cache = "MISS";
  }
}

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

sub vcl_miss {
    if (req.request == "PURGE") {
        purge;
        error 200 "Not in cache";
    }
}