gistfile1.c

backend default {
.host = "backendhost";
.port = "80";
  .probe = {
    .url = "/probe.html";
    .timeout = 10 s;
    .interval = 30 s;
    .window = 10;
    .threshold = 8;
    .initial = 10;
  }
}
sub vcl_recv {
  set req.http.Host = "backendhost";
  if (req.backend.healthy) {
    set req.grace = 30s;
  } else {
    set req.grace = 1h;
  }

  if (req.request != "GET" &&
    req.request != "HEAD" &&
    req.request != "PUT" &&
    req.request != "POST" &&
    req.request != "TRACE" &&
    req.request != "OPTIONS" &&
    req.request != "DELETE") {
      /* Non-RFC2616 or CONNECT which is weird. */
      return (pipe);
  }
  if (req.request != "GET" && req.request != "HEAD") {
      /* We only deal with GET and HEAD by default */
      return (pass);
  }

  return(lookup);
}
sub vcl_fetch {
  if (beresp.ttl < 300s) {
   set beresp.ttl = 300s;
  }
}