task_runner: emit event on task exit with exit result details

client/allocrunner/taskrunner/task_runner.go

@@ -369,6 +369,9 @@ MAIN:
 				select {
 				case result = <-resultCh:
 					// WaitCh returned a result
+					if result != nil {
+						tr.handleTaskExitResult(result)
+					}
 				case <-tr.ctx.Done():
 					// TaskRunner was told to exit immediately
 					return
@@ -410,6 +413,7 @@ MAIN:
 		event := structs.NewTaskEvent(structs.TaskTerminated).
 			SetExitCode(result.ExitCode).
 			SetSignal(result.Signal).
+			SetOOMKilled(result.OOMKilled).
 			SetExitMessage(result.Err)
 		tr.UpdateState(structs.TaskStateDead, event)
 	}
@@ -422,6 +426,20 @@ MAIN:
 	tr.logger.Debug("task run loop exiting")
 }
 
+func (tr *TaskRunner) handleTaskExitResult(result *drivers.ExitResult) {
+	event := structs.NewTaskEvent(structs.TaskTerminated).
+		SetExitCode(result.ExitCode).
+		SetSignal(result.Signal).
+		SetOOMKilled(result.OOMKilled).
+		SetExitMessage(result.Err)
+
+	tr.EmitEvent(event)
+
+	if !tr.clientConfig.DisableTaggedMetrics {
+		metrics.IncrCounterWithLabels([]string{"client", "allocs", "oom_killed"}, 1, tr.baseLabels)
+	}
+}
+
 // handleUpdates runs update hooks when triggerUpdateCh is ticked and exits
 // when Run has returned. Should only be run in a goroutine from Run.
 func (tr *TaskRunner) handleUpdates() {

nomad/structs/structs.go

@@ -6196,6 +6196,11 @@ func (e *TaskEvent) SetDriverMessage(m string) *TaskEvent {
 	return e
 }
 
+func (e *TaskEvent) SetOOMKilled(oom bool) *TaskEvent {
+	e.Details["oom_killed"] = strconv.FormatBool(oom)
+	return e
+}
+
 // TaskArtifact is an artifact to download before running the task.
 type TaskArtifact struct {
 	// GetterSource is the source to download an artifact using go-getter