Event Bridge

The EventBridge lambda event source allows you to trigger lambda functions in response to either cron schedules or account events. There are two different archetype functions available.

Scheduled

Scheduled Lambdas execute either at fixed times or periodically depending on the schedule expression.

To create a scheduled function use a constructor as in:

import (
  spartaArchetype "github.com/mweagle/Sparta/archetype"
)

// EventBridge reactor function
func echoEventBridgeEvent(ctx context.Context, msg json.RawMessage) (interface{}, error) {
  logger, _ := ctx.Value(sparta.ContextKeyLogger).(*logrus.Logger)
  var eventData map[string]interface{}
  err := json.Unmarshal(msg, &eventData)
  logger.WithFields(logrus.Fields{
    "error":   err,
    "message": eventData,
  }).Info("EventBridge event")
  return nil, err
}

func main() {
  // ...
  eventBridgeReactorFunc := spartaArchetype.EventBridgeReactorFunc(echoEventBridgeEvent)
  lambdaFn, lambdaFnErr := spartaArchetype.NewEventBridgeScheduledReactor(eventBridgeReactorFunc,
    "rate(1 minute)",
    nil)
  // ...
}

When the scheduled event is triggered, the log statement outputs the full payload:

{
  "error": null,
  "level": "info",
  "message": {
    "account": "123412341234",
    "detail": {},
    "detail-type": "Scheduled Event",
    "id": "f453bd1e-ccea-9df4-4e40-938097e82869",
    "region": "us-west-2",
    "resources": [
      "arn:aws:events:us-west-2:123412341234:rule/SpartaEventBridge-0271594-EventBridgexmainechoEven-2WMCXA1LWGZY"
    ],
    "source": "aws.events",
    "time": "2020-02-23T00:47:31Z",
    "version": "0"
  },
  "msg": "EventBridge event",
  "time": "2020-02-23T00:48:08Z"
}

See the scheduled event payload documentation.

Events

Lambda functions can also be triggered via EventBridge by providing an event patterns to select which events should trigger your function’s execution.

To create an event subscriber use a constructor as in:

func echoEventBridgeEvent(ctx context.Context, msg json.RawMessage) (interface{}, error) {
  logger, _ := ctx.Value(sparta.ContextKeyLogger).(*logrus.Logger)
  var eventData map[string]interface{}
  err := json.Unmarshal(msg, &eventData)
  logger.WithFields(logrus.Fields{
    "error":   err,
    "message": eventData,
  }).Info("EventBridge event")
  return nil, err
}

func main() {
  // ...
  eventBridgeReactorFunc := spartaArchetype.EventBridgeReactorFunc(echoEventBridgeEvent)
  lambdaFn, lambdaFnErr := spartaArchetype.NewEventBridgeEventReactor(eventBridgeReactorFunc,
    map[string]interface{}{
      "source": []string{"aws.ec2"},
    },
    nil)
  // ...
}

The event payload data depends on what event is being subscribed to. See the event patterns documentation for more information.