fix: set CORS error content type to text/html by default

refs #385

Author: theseion

README.md

@@ -220,7 +220,7 @@ These variables are common to image variants and will set defaults based on the
 | -------- | ------------------------------------------------------------------- |
 | CORS_HEADER_403_ALLOW_ORIGIN | The value of the [Access-Control-Allow-Origin](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin) header for `403` responses. Determines which origins can access the response. (Default: `"*"`). |
 | CORS_HEADER_403_ALLOW_METHODS | The value of the [Access-Control-Request-Method](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Request-Method) header for `403` responses. Determines the allowed request methods for the resource. Default: `"GET, POST, PUT, DELETE, OPTIONS"` |
-| CORS_HEADER_403_CONTENT_TYPE | The value of the  `Content-Type` header for `403` responses. Default: (`"text/plain"`) |
+| CORS_HEADER_403_CONTENT_TYPE | The value of the  `Content-Type` header for `403` responses. Default: (`"text/html"`) |
 | CORS_HEADER_403_MAX_AGE | The value of the [Access-Control-Max-Age](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Max-Age) header for `403` responses. The number of seconds that preflight requests for this resource may be cached by the browser. (Default: `3600`) |
 | DNS_SERVER  | Deprecated. Use `RESOLVERS`.
 | HTTP2 | A string value indicating whether HTTP/2 should be enabled (for all locations) (Allowed values: `on`, `off`. Default: `on`) |

nginx/Dockerfile

@@ -134,7 +134,7 @@ ENV \
     BACKEND=http://localhost:80 \
     CORS_HEADER_403_ALLOW_ORIGIN="*" \
     CORS_HEADER_403_ALLOW_METHODS="GET, POST, PUT, DELETE, OPTIONS" \
-    CORS_HEADER_403_CONTENT_TYPE="text/plain" \
+    CORS_HEADER_403_CONTENT_TYPE="text/html" \
     CORS_HEADER_403_MAX_AGE=3600 \
     CORS_HEADER_ACCESS_CONTROL_ALLOW_HEADERS="*" \
     ERRORLOG=/var/log/nginx/error.log \