fix(ui): ensure that UI nginx routes to index.html as fallback (#824)

As we're using virtual page routing in our UI, URLs which are unknown to
nginx should redirect to the index.html so that they can be resolved by
the React router.

Dockerfile.ui

@@ -9,4 +9,6 @@ RUN npm run build
 
 FROM nginx:1.25.2
 
+COPY --from=site-build ["/app/ui-build/nginx.conf", "/etc/nginx/conf.d/default.conf"]
+
 COPY --from=site-build ["/app/ui-build/build", "/usr/share/nginx/html"]

ui/nginx.conf

@@ -0,0 +1,22 @@
+server {
+    listen       80;
+    listen  [::]:80;
+    server_name  localhost;
+
+    #access_log  /var/log/nginx/host.access.log  main;
+
+    location / {
+        root   /usr/share/nginx/html;
+        index  index.html index.htm;
+        try_files $uri $uri/ /index.html;
+    }
+
+    #error_page  404              /404.html;
+
+    # redirect server error pages to the static page /50x.html
+    #
+    error_page   500 502 503 504  /50x.html;
+    location = /50x.html {
+        root   /usr/share/nginx/html;
+    }
+}