Add isos.acmcsuf.com

This will serve as our mirror for ISOs and other large images that we
want to keep immutable, such as Ubuntu ISOs.

Official mirrors are allowed to change these files over time which
violates Nix's immutability guarantees, so we'll mirror them ourselves.

servers/cs306/caddy/Caddyfile

@@ -66,3 +66,14 @@ netdata.acmcsuf.com {
 madness.acmcsuf.com {
 	reverse_proxy * localhost:8391
 }
+
+# Host ISOs locally for the club.
+# ISOs stored here must be immutable. New ISO releases must have a different
+# file path.
+isos.acmcsuf.com {
+	file_server {
+		root /var/www/isos
+		browse
+	}
+	header Cache-Control "public, max-age=31536000, immutable"
+}

servers/cs306/caddy/default.nix

@@ -22,4 +22,9 @@ in
 		configFile = preprocessedCaddyfile;
 		inherit environment;
 	};
+
+	systemd.tmpfiles.rules = [
+		"d /var/www      0755 caddy caddy -"
+		"d /var/www/isos 0755 root root -"
+	];
 }