Custom error pages for nginx ingress controller

10-nginx.conf

################################################################################
## Custom headers forwarded by the nginx ingress controller                   ##
##                                                                            ##
## X-Code               HTTP status code retuned by the request               ##
## X-Format             Value of the Accept header sent by the client         ##
## X-Original-URI       URI that caused the error                             ##
## X-Namespace          Namespace where the backend Service is located        ##
## X-Ingress-Name       Name of the Ingress where the backend is defined      ##
## X-Service-Name       Name of the Service backing the backend               ##
## X-Service-Port       Port number of the Service backing the backend        ##
## X-Request-ID         Unique ID that identifies the request -               ##
##                      same as for backend service                           ##
################################################################################

user              nginx;
worker_processes  auto;
pid               /var/run/nginx.pid;

events {
    worker_connections  1024;
}

http {
    include            /etc/nginx/mime.types;
    default_type       application/octet-stream;
    sendfile           on;
    keepalive_timeout  65;

    map $request_time $total_request_time {
      default $request_time;
      ""      0;
      "~(-,)" 0;
      "~([^,\s]+\s*)$" $1;
    }

    map $request_length $total_request_length {
      default $request_length;
      ""      0;
      "~(-,)" 0;
      "~([^,\s]+\s*)$" $1;
    }

    log_format main escape=json '{"@timestamp": "$time_iso8601","zs_component": "zaaksysteem-custom-errors", "zs_pod_name": "$hostname", "service_name": "$http_x_service_name", "service_port": "$http_x_service_port", "ingress_name": "$http_x_ingress_name", "ingress_request_id": "$http_x_request_id", "message": "$request", "vhost": "$host", "req": { "remote_addr": "$remote_addr", "x-forward-for": "$proxy_add_x_forwarded_for", "hostname": "$host", "namespace": "$http_x_namespace", "format": "$http_x_format", "instance_hostname": "$host", "action_path": "$http_x_original_uri", "remote_user": "$remote_user", "body_bytes_sent": $body_bytes_sent, "status": $status, "original_status": "$http_x_code", "request_uri": "$request_uri", "request_method": "$request_method", "request_time": $total_request_time, "request_length": $total_request_length, "request_proto": "$server_protocol", "request_completion": "$request_completion", "http_referrer": "$http_referer", "http_user_agent": "$http_user_agent"}}';

    rewrite_log off;
    access_log /dev/stdout main;
    error_log /dev/stderr error;

    map $http_x_code $internal_redirect {
      default /523;

        404   /404;
	418   /418;
        429   /429;
        500   /500;
        502   /502;
        503   /503;
        523   /523;
    }

    server {
        listen 8080 default_server;

        error_page 404 /error_pages/error_404.html;
        error_page 429 /error_pages/error_429.html;
        error_page 418 /error_pages/error_418.html;
        error_page 500 /error_pages/error_500.html;
        error_page 502 /error_pages/error_502.html;
        error_page 503 /error_pages/error_503.html;
        error_page 523 /error_pages/error_523.html;

        location /healthz {
            access_log off;
            return 200 "healthy\n";
        }

        location /metrics {
            stub_status on;
        }

	location @internal_redirect {
            rewrite "^(.*)/?" $internal_redirect last;
	}

	location / {
	    try_files $uri @internal_redirect;
        }

	location /error_pages/ {
	    root /var/www/html;
        }

        location = /404 { internal; return 404; }
        location = /418 { internal; return 418; }
        location = /429 { internal; return 429; }
        location = /500 { internal; return 500; }
        location = /502 { internal; return 502; }
        location = /503 { internal; return 503; }
        location = /523 { internal; return 523; }
    }
}

50-values.yaml

ingress:
  ...

  defaultBackend:
    enabled: true
    replicaCount: 3
    image:
      runAsUser: 0     ## nginx forks to used nginx
      pullPolicy: Always
      repository: registry.gitlab.com/mintlab/devops/docker/ingress-custom-errors
      tag: latest

  ...
  imagePullSecrets:
  - name: gitlab-key

  ...
  controller:
    config:
      custom-http-errors: 404,429,418,500,502,503,523

99-Dockerfile

FROM nginx:alpine

RUN set -ex \
 && rm -rvf /etc/nginx/nginx.conf /etc/nginx/conf.d

COPY www/ /var/www/html/
COPY nginx.conf /etc/nginx/nginx.conf

RUN date > /etc/buildtime

EXPOSE 8080
CMD ["nginx", "-g", "daemon off;"]