feat(whitby): Enable SourceGraph server

Change-Id: Ia8a20d54a4ac77d64f5e3fd2255ffad78dce0fb0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1067
Tested-by: BuildkiteCI
Reviewed-by: lukegb <lukegb@tvl.fyi>

ops/nixos/www/cs.tvl.fyi.nix

@@ -0,0 +1,30 @@
+{ config, ... }:
+
+{
+  imports = [
+    ./base.nix
+  ];
+
+  config = {
+    services.nginx.virtualHosts."cs.tvl.fyi" = {
+      serverName = "cs.tvl.fyi";
+      enableACME = true;
+      forceSSL = true;
+
+      extraConfig = ''
+        location = / {
+          return 301 https://cs.tvl.fyi/depot;
+        }
+
+        location / {
+          proxy_set_header X-Sg-Auth "Anonymous";
+          proxy_pass http://localhost:${toString config.services.depot.sourcegraph.port};
+        }
+
+        location /users/Anonymous/settings {
+          return 301 https://cs.tvl.fyi;
+        }
+      '';
+    };
+  };
+}