Replace ReadonlyTargets interface with a TargetsConfig channel

A channel provides a simple and safe interface for config updates. The in-memory
config is no longer needed as tests can simply write config values to the config
channel. For the volume config the config channel replaces the notify channel
and the config watcher writes updated config values to the channel.

cmd/broker/ingress/main.go

@@ -17,6 +17,7 @@ limitations under the License.
 package main
 
 import (
+	"github.com/google/knative-gcp/pkg/broker/config/volume"
 	"github.com/google/knative-gcp/pkg/broker/ingress"
 	"github.com/google/knative-gcp/pkg/utils"
 	"github.com/kelseyhightower/envconfig"
@@ -52,7 +53,11 @@ func main() {
 	}
 	logger.Desugar().Info("Starting ingress handler", zap.Any("envConfig", env), zap.Any("Project ID", projectID))
 
-	ingress, err := ingress.NewHandler(ctx, ingress.WithPort(env.Port), ingress.WithProjectID(projectID))
+	targets, err := volume.NewTargetsFromFile()
+	if err != nil {
+		logger.Desugar().Fatal("Unable to get targets config: %v", zap.Error(err))
+	}
+	ingress, err := ingress.NewHandler(ctx, targets, ingress.WithPort(env.Port), ingress.WithProjectID(projectID))
 	if err != nil {
 		logger.Desugar().Fatal("Unable to create ingress handler: ", zap.Error(err))
 	}