We will start from scratch using the handwriting YAML file method to deploy a K8S cluster of EMQX MQTT broker, and analyze details and techniques of the deployment.

EMQX provides a complete IoT private TCP protocol access solution through server adaptation and device-side adaptation.

The message retention function of [EMQX MQTT Broker](https://emqx.io) is implemented by the `emqx_retainer` plugin, which is enabled by default. By modifying the configuration of the` emqx_retainer` plugin, you can adjust the EMQX Broker's retention message Location, restrict the number of retained messages and maximum payload length, and adjust the expiration time of retained messages.

Helm3 was released in November 2019, which adds many new features compared to Helm2.In this article, how to deploy EMQX cluster on Kubernetes via Helm3 will be introduced.