ExpressionEngine Varnish 4.0

vcl 4.0;

backend default {
    .host = "127.0.0.1";  # The domain or IP address of your ExpressionEngine Site
    .port = "8080";       # The port of your EE site. In production, Varnish should be on port 80, so consider changing your Apache server to port 8080
    .probe = {
        .url = "/";
        .timeout = 1000ms;
        .interval = 1s;
        .window = 10;
        .threshold = 8;
    }
}

sub vcl_recv {

    # Forward client's IP to backend
    unset req.http.X-Forwarded-For;
    set req.http.X-Forwarded-For = client.ip;

    # Set the URI of your system directory
    # In this example, we assume your admin interface is in "system", so just ensure it's right for your setup.
    if (req.url ~ "^/system/" ||
        req.url ~ "ACT=" ||
        req.method == "POST" ||
        (req.url ~ "member_box" && req.http.Cookie ~ "exp_sessionid"))
    {
        return (pass);
    }

    unset req.http.Cookie;

    # This is different, read this: https://www.varnish-software.com/blog/grace-varnish-4-stale-while-revalidate-semantics-varnish
    # set req.grace = 1h;

    return(hash);
}

sub vcl_backend_response {

    # Enable ESI includes
    set beresp.do_esi = true;

    # Our cache TTL
    set beresp.ttl = 1m;

    # set beresp.grace = 1h;

    return(deliver);
}