main can run many pipelines

main.go

@@ -36,22 +36,28 @@ func run(ctx context.Context, cfg Config) error {
 	select {
 	case <-ctx.Done():
 		return ctx.Err()
-	case err := <-processSlackToMessagePipeline(ctx, cfg):
+	case err := <-processPipelines(ctx, cfg.slackToMessagePipeline):
 		return err
 	case err := <-listenAndServe(ctx, cfg):
 		return err
 	}
 }
 
-func processSlackToMessagePipeline(ctx context.Context, cfg Config) chan error {
+func processPipelines(ctx context.Context, first Pipeline, pipelines ...Pipeline) chan error {
+	ctx, can := context.WithCancel(ctx)
+	defer can()
+
+	pipelines = append(pipelines, first)
 	errs := make(chan error)
-	go func() {
+	for i := range pipelines {
+		go func(i int) {
 			defer close(errs)
 			select {
-		case errs <- cfg.slackToMessagePipeline.Process(ctx):
+			case errs <- pipelines[i].Process(ctx):
 			case <-ctx.Done():
 			}
-	}()
+		}(i)
+	}
 	return errs
 }