emqx/apps/emqx_eviction_agent

EMQX Eviction Agent

emqx_eviction_agent is a part of the node evacuation/node rebalance feature in EMQX. It is a low-level application that encapsulates working with actual MQTT connections.

Application Responsibilities

emqx_eviction_agent application:

• Blocks incoming connection to the node it is running on.
• Serves as a facade for connection/session eviction operations.
• Reports blocking status via HTTP API.

The emqx_eviction_agent is relatively passive and has no eviction/rebalancing logic. It allows emqx_node_rebalance to perform eviction/rebalancing operations using high-level API, without having to deal with MQTT connections directly.

EMQX Integration

emqx_eviction_agent interacts with the following EMQX components:

• emqx_cm - to get the list of active MQTT connections;
• emqx_hooks subsystem - to block/unblock incoming connections;
• emqx_channel and the corresponding connection modules to perform the eviction.

User Facing API

The application provided a very simple API (CLI and HTTP) to inspect the current blocking status.

Documentation

The rebalancing concept is described in the corresponding EIP.

Contributing

Please see our contributing.md.