custom error pages for nginx ingress controller

Question

I was trying to get nice error pages, when my kubernetes service is not working (replicas: 0). So I found the following resources:

• https://github.com/kubernetes/ingress-nginx/tree/master/docs/examples/customization/custom-errors
• https://github.com/kubernetes/ingress-nginx/tree/master/images/custom-error-pages
• https://tech.holidayextras.com/custom-error-handling-with-the-kubernetes-nginx-ingress-controller-f7861b08ffd7

The custom-error-pages Go sources need to be compiled, which I tried to avoid. So I searched for a prebuilt Docker image and I found one on quay.io:

• quay.io/kubernetes-ingress-controller/custom-error-pages-amd64

But, quay.io complained about some security risks in the image, so I searched for another solution. My idea was to get a similar solution with a standard nginx web server.

Needed features:

• Serve a nice custom error page with css
• Serve a json reply when called with Accept: application/json
• Return the error code given for nginx ingress controller in the header X-Code
• The served error page should depend on the error code (4xx vs. 5xx)

After some research, I came up with the following solution:

server {

  listen 0.0.0.0:8080;
  server_name default;
  root /app;

  location /healthz {
    return 200 "ok";
  }

  location /status {
    stub_status on;
    access_log off;
    allow 127.0.0.1;
    deny all;
  }

  set $uri_and_code "${http_x_original_uri}${http_x_code}";

  set $type "html";

  if ($http_x_format = 'application/json') {
    set $type "json";
  }

  error_page 403 404 /4xx.${type};
  error_page 500 502 503 504 /5xx.${type};

  location /4xx { internal; }
  location /5xx { internal; }

  location / {
    if ($http_x_original_uri = '') { return 404; }
    if ($uri_and_code = '/403') { return 403; }
    if ($uri_and_code = '/404') { return 404; }
    if ($uri_and_code = '/502') { return 502; }
    if ($uri_and_code = '/503') { return 503; }
    if ($uri_and_code = '/504') { return 504; }

    try_files $http_x_original_uri $uri $uri/ =404;
  }

  location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ {
    expires max;
    log_not_found off;
  }

  location ~* ^.+.(ogg|ogv|svg|svgz|eot|otf|woff|mp4|ttf|rss|atom|jpg|jpeg|gif|png|ico|zip|tgz|gz|rar|bz2|doc|xls|exe|ppt|tar|mid|midi|wav|bmp|rtf)$ {
    access_log off;
    log_not_found off;
    expires max;
  }

}

I'm not fully satisfied, because it relies on if statements in location / (ifisevil). Is there a better solution?

Cheers,

floek