This tutorial outlines the process of creating a custom Kong Gateway plugin using the Go programming language, focusing on enhancing security by adding an extra layer between consumers and producers. The plugin identifies consumers through a consumer-key in the query string, and without it, an error message is returned. The process involves using the declarative configuration (decK), importing the Go Plugin Development Kit (PDK), and building a Docker image to run the plugin as a container. The plugin acts as middleware, checking for the correct API key for each request and redirecting URLs as necessary. The tutorial highlights the flexibility and expanded capabilities that custom plugins bring to Kong Gateway, encouraging users to explore further resources and engage with the Kong community for additional insights and support.