EventBus Metrics and UI

EventBus.Metrics

Metrics library and metrics RESTFul endpoints for event_bus

Installation

The package can be installed by adding event_bus_metrics to your list of dependencies in mix.exs:

def deps do
  [
    {:event_bus_metrics, "~> 0.3"}
  ]
end

Add event_bus_metrics to the extra_applications list:

def application do
  [
    extra_applications: [..., :event_bus, :event_bus_metrics, ...],
    ...
  ]
end

Update your config.exs

config :event_bus_metrics,
  cross_origin: {:system, "EB_CROSS_ORIGIN", "off"},
  http_server: {:system, "EB_HTTP_SERVER", "off"},
  http_server_port: {:system, "PORT", "4000"},
  # Server-Sent-Events Tickers:
  notify_subscriber_metrics_in_ms: {:system, "EB_SUBSCRIBER_M_IN_MS", 250},
  notify_topic_metrics_in_ms: {:system, "EB_TOPIC_M_IN_MS", 1000},
  notify_topics_metrics_in_ms: {:system, "EB_TOPICS_M_IN_MS", 250}

Endpoints

In your router.ex, forward an unused path to EventBus.Metrics.Web.Router like below:

forward "/event_bus", to: EventBus.Metrics.Web.Router

UI

HTTP Path for UI: /event_bus/ui/

To open and use the UI open the https://{your_host_name}/event_bus/ui/. Note: The URL path must end with '/' char.

Topics

GET /event_bus/topics # All topic metrics

GET /event_bus/topics/:topic_name # Specific topic metrics

GET /event_bus/topics/:topic_name/events # Topic event metrics (only unprocessed events)

GET /event_bus/topics/:topic_name/events/:event_id # Event details (only unprocessed events)

Subscribers

GET /event_bus/subscribers # All subscriber metrics

Server-Sent-Events (stream live metrics)

GET /event_bus/sse # Streaming endpoint for metrics

Screenshots

• Node setting

• List of topics

• Topic details

Notes

I personally use event_bus_metrics library in the development environment to debug events, topics, and subscriber chain. It purely uses event_bus library ETS tables to fetch event related data to give an idea of what is happening on your local message bus system. For example; if a consumer doesn't implement either mark_as_completed or mark_as_skipped calls, for a specific event, you can observe it with the event_bus_metrics UI.

Warning: The event_bus_metrics library only gives information about connected node.

Demo

When someone sends a message to trollboxbot, metrics will update with Server Sent Events on EventBus Metrics UI