Example varnish and hitch config (#2655)

Varnish is a http caching server, hitch is a tls terminating proxy.

contrib/varnish/vanish.vcl

@@ -0,0 +1,38 @@
+vcl 4.0;
+
+backend default {
+	.host = "localhost";
+	.port = "8080";
+}
+
+sub vcl_recv {
+	# Implementing websocket support (https://www.varnish-cache.org/docs/4.0/users-guide/vcl-example-websockets.html)
+	if (req.http.Upgrade ~ "(?i)websocket") {
+		return (pipe);
+	}
+}
+
+sub vcl_pipe {
+	if (req.http.upgrade) {
+		set bereq.http.upgrade = req.http.upgrade;
+		set bereq.http.connection = req.http.connection;
+	}
+}
+
+sub vcl_backend_response {
+	# Set 1s ttl if origin response HTTP status code is anything other than 200
+	if (beresp.status != 200) {
+		set beresp.ttl = 1s;
+		set beresp.uncacheable = true;
+		return (deliver);
+	}
+	if (bereq.url ~ "m3u8") {
+		# assuming chunks are 2 seconds long
+		set beresp.ttl = 1s;
+		set beresp.grace = 0s;
+	}
+	if (bereq.url ~ "ts") {
+		set beresp.ttl = 10m;
+		set beresp.grace = 5m;
+	}
+}