Simple NGINX config to dump CSP reports

nginx.csp.conf

server {
  listen 80;
  server_name site.mozilla.org;

  location / {
    return 301 https://$server_name$request_uri;
  }

  location /twohundredinator {
    access_log off;
    allow 127.0.0.1;
    return 200;
  }
}

server {
  listen 443;
  server_name site.mozilla.org;

  root /var/www/site.mozilla.org;
  index index.html;

  add_header Content-Security-Policy "default-src 'none'; frame-ancestors 'self'";
  add_header Strict-Transport-Security "max-age=31536000";
  add_header X-Content-Type-Options "nosniff";
  add_header X-Frame-Options "DENY";
  add_header X-XSS-Protection "1; mode=block";

  location /__cspreporting__ {
    access_log /var/log/nginx/report-uri-csp.log CSP;
    proxy_pass http://127.0.0.1/twohundredinator;
  }

  ssl on;
  ssl_certificate /etc/certificates/site.mozilla.org.crt;
  ssl_certificate_key /etc/certificates/site.mozilla.org.org.key;

  ssl_protocols TLSv1.2;
  ssl_ciphers 'ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256';
  ssl_prefer_server_ciphers on;
}

Why is a proxy_pass being used to forward to port 80? Why not use the following directly:

location /__cspreporting__ {
    access_log /var/log/nginx/report-uri-csp.log CSP;
}

Thanks for that code snipped, that leads me to the correct solution. The log format 'CSP' has to be defined somewhere in the http directive in nginx configuration:

log_format CSP escape=json $request_body;

or a longer definition (from [1]):

log_format  CSP '$remote_addr - [$time_local] '
        '"$http_referer" "$content_type" "$http_user_agent" "$request_body"';

@basilmusa: According to [2] you "Nginx doesn't parse the client request body unless it really needs to, so it usually does not fill the $request_body variable."

Edit: I optimized the log_format so it's all JSON:

log_format CSP '{"date":"$time_local", "IP address":"$remote_addr", "http_x_forwarded_for":"$http_x_forwarded_for", "status":"$status", "http_user_agent":"$http_user_agent", "body_bytes_sent":"$body_bytes_sent", "request":"$request","request-body": $request_body}';

The log file escapes the double quotes with \x22 so with a sed an jq you get a proper JSON log of the CSP report:

sed 's/\\x22//g' csp2.log | jq