JSON error page for Nginx

Graham Hay

We use the ngx_http_auth_request_module to authenticate requests by calling one of our services. Unfortunately, if the request is rejected, it returns the default 401 error page:

<html>
<head><title>401 Authorization Required</title></head>
<body bgcolor="white">
<center><h1>401 Authorization Required</h1></center>
<hr><center>nginx/1.9.10</center>
</body>
</html>

Which is a bit out of place, when the rest of our responses are JSON. A simple fix is to override it:

server {
    ...
    error_page 401 @401_json;

    location @401_json {
        default_type application/json;
        return 401 '{"error":{"message":"Unauthorised"}}';
    }
}

But remember this will be used for all 401s, not just those from the auth module.

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