Nginx is a popular reverse proxy and load balancer that focuses on level 7 (application) traffic. A common pattern is allowing Nginx to be the fronting SSL-termination point, and then Nginx determines which pooled backend server is best available to serve the request.
Nginx is a powerful application level proxy server. Whether for troubleshooting or analysis, enabling log levels and custom formats for the access/error logs is a common requirement.
By default, only messages in the error category are logged. If you want to enable more details, then modify nginx.conf like:
error_log file [level]
Enabling debug level on Linux would usually look like:
error_log /var/log/nginx/error.log debug;
access_log file [format]