HAWNG-6: Adds custom 404 and 50x error pages

* Avoids revealing type or version of web server used by displaying
  custom error pages

Dockerfile

@@ -73,6 +73,9 @@ RUN mkdir -p /usr/share/nginx/html/online/osconsole && \
 COPY docker/nginx.js docker/rbac.js docker/js-yaml.js docker/jwt-decode.js /etc/nginx/conf.d/
 COPY docker/nginx.conf docker/nginx-gateway.conf.template docker/nginx-gateway-k8s.conf.template docker/osconsole/config.sh docker/nginx.sh docker/ACL.yaml /
 
+COPY docker/hawtio-50x.html /usr/share/nginx/html
+COPY docker/hawtio-404.html /usr/share/nginx/html
+
 # Copy licenses
 RUN mkdir -p /opt/hawtio/licenses
 COPY docker/licenses /opt/hawtio/licenses

docker/hawtio-404.html

@@ -0,0 +1,13 @@
+<div style="text-align: center">
+  <h1>Whoops!</h1>
+  <p style="color: red; font-weight: bold;">
+    404 Page Not Found
+  </p>
+  <div>
+    <span style="box-sizing:border-box;display:inline-block;overflow:hidden;width:initial;height:initial;background:none;opacity:1;border:0;margin:0;padding:0;position:relative;max-width:100%">
+      <img alt="Hawtio Logo" src="/online/hawtio-logo.svg">
+    </span>
+  </div>
+  <p class=>Try <a title="Go to Hawtio Online" href="/online">Hawtio</a>.
+  </p>
+</div>

docker/hawtio-50x.html

@@ -0,0 +1,13 @@
+<div style="text-align: center">
+  <h1>Whoops!</h1>
+  <p style="color: red; font-weight: bold;">
+    A connection error occurred.
+  </p>
+  <div>
+    <span style="box-sizing:border-box;display:inline-block;overflow:hidden;width:initial;height:initial;background:none;opacity:1;border:0;margin:0;padding:0;position:relative;max-width:100%">
+      <img alt="Hawtio Logo" src="/online/hawtio-logo.svg">
+    </span>
+  </div>
+  <p class=>Try <a title="Go to Hawtio Online" href="/online">Hawtio</a>.
+  </p>
+</div>

docker/nginx-gateway-k8s.conf.template

@@ -36,6 +36,16 @@ server {
         rewrite ^ $new redirect;
     }
 
+    error_page 404 /hawtio-404.html;
+    location = /hawtio-404.html {
+        internal;
+    }
+
+    error_page 500 502 503 504 /hawtio-50x.html;
+    location = /hawtio-50x.html {
+        internal;
+    }
+
     # Static content serving
     location /online {
         add_header location-rule ONLINE always;

docker/nginx-gateway.conf.template

@@ -36,6 +36,16 @@ server {
         rewrite ^ $new redirect;
     }
 
+    error_page 404 /hawtio-404.html;
+    location = /hawtio-404.html {
+        internal;
+    }
+
+    error_page 500 502 503 504 /hawtio-50x.html;
+    location = /hawtio-50x.html {
+        internal;
+    }
+
     # Static content serving
     location /online {
         add_header location-rule ONLINE always;

docker/nginx.conf

@@ -20,6 +20,16 @@ server {
         rewrite ^ $new redirect;
     }
 
+    error_page 404 /hawtio-404.html;
+    location = /hawtio-404.html {
+        internal;
+    }
+
+    error_page 500 502 503 504 /hawtio-50x.html;
+    location = /hawtio-50x.html {
+        internal;
+    }
+
     # Static content serving
     location /online {
         alias     /usr/share/nginx/html/online;