Fix caching headers on Docker image

config/nginx.conf

@@ -2,9 +2,24 @@ server {
     listen       8080;
     server_name  localhost;
 
+    root   /app;
+
     location / {
-        root   /app;
+        # disable cache entriely by default (apart from Etag which is accurate enough)
+        add_header Cache-Control 'private no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0';
+        if_modified_since off;
+        expires off;
+        # also turn off last-modified since they are just the timestamps of the file in the docker image
+        # and may or may not bear any resemblance to when the resource changed
+        add_header Last-Modified "";
+
         try_files $uri /$uri /index.html;
     }
+
+    # assets can be cached because they have hashed filenames
+    location /assets {
+        expires 1w;
+        add_header Cache-Control "public, no-transform";
+    }
 }