dundee/gist:4681935

## gistfile1.txt
acl local {
	"localhost";
}

backend default {
	.host = "127.0.0.1";
	.port = "80";
	.first_byte_timeout = 3s;
}

backend fake {
        .host = "127.0.0.1";
        .port = "81";
        .probe = {
                .timeout = 0.1s;
        }
}

sub vcl_recv {
	# Handle timeout from backend
	if ( req.http.magicmarker && req.http.magicmarker == "fake" ) {
		unset req.http.magicmarker;
		set req.backend = fake;
	} else {
		set req.backend = default;
	}

	# Refresh cache on X-REFRESH header
	if (req.http.X-REFRESH && client.ip ~ local) {
		set req.hash_always_miss = true;
	}

	# Serve stale data if needed
	if (!req.backend.healthy) {
		set req.grace = 5h;
	} else {
		set req.grace = 1h;
	}
}

sub vcl_fetch {
	# Process ESI
	set beresp.do_esi = true;

	# Do not overload backend if returns error
	if (beresp.status >= 500) {
		set beresp.saintmode = 10m; # try again after 10m
		return(restart);
	}

	# Cache entry for 5 more hours than TTL
	set beresp.grace = 5h;

	return (deliver);
}

sub vcl_error {
	# Handle timeout from backend
	if (obj.status == 503 && req.restarts < 5) {
		if (req.restarts == 0){
			set req.http.magicmarker = "fake";
		}
		return(restart);
	}

	set obj.http.Content-Type = "text/html; charset=utf-8";
	set obj.http.Retry-After = "5";
	synthetic {"
		<!DOCTYPE html>
		<html>
			<head>
				<title>"} + obj.status + " " + obj.response + {"</title>
			</head>
			<body>
				<h1>Error "} + obj.status + " " + obj.response + {"</h1>
				<p>"} + obj.response + {"</p>
			</body>
		</html>
	"};
	return (deliver);
}
	acl local {
	"localhost";
	}

	backend default {
	.host = "127.0.0.1";
	.port = "80";
	.first_byte_timeout = 3s;
	}

	backend fake {
	.host = "127.0.0.1";
	.port = "81";
	.probe = {
	.timeout = 0.1s;
	}
	}

	sub vcl_recv {
	# Handle timeout from backend
	if ( req.http.magicmarker && req.http.magicmarker == "fake" ) {
	unset req.http.magicmarker;
	set req.backend = fake;
	} else {
	set req.backend = default;
	}

	# Refresh cache on X-REFRESH header
	if (req.http.X-REFRESH && client.ip ~ local) {
	set req.hash_always_miss = true;
	}

	# Serve stale data if needed
	if (!req.backend.healthy) {
	set req.grace = 5h;
	} else {
	set req.grace = 1h;
	}
	}

	sub vcl_fetch {
	# Process ESI
	set beresp.do_esi = true;

	# Do not overload backend if returns error
	if (beresp.status >= 500) {
	set beresp.saintmode = 10m; # try again after 10m
	return(restart);
	}

	# Cache entry for 5 more hours than TTL
	set beresp.grace = 5h;

	return (deliver);
	}

	sub vcl_error {
	# Handle timeout from backend
	if (obj.status == 503 && req.restarts < 5) {
	if (req.restarts == 0){
	set req.http.magicmarker = "fake";
	}
	return(restart);
	}

	set obj.http.Content-Type = "text/html; charset=utf-8";
	set obj.http.Retry-After = "5";
	synthetic {"
	<!DOCTYPE html>
	<html>
	<head>
	<title>"} + obj.status + " " + obj.response + {"</title>
	</head>
	<body>
	<h1>Error "} + obj.status + " " + obj.response + {"</h1>
	<p>"} + obj.response + {"</p>
	</body>
	</html>
	"};
	return (deliver);
	}