asset/store: log asset creation

This makes it clear when and why a particular asset was created so it
should help with debugging. The output of this looks as follows:

    INFO[0000] Fetching Bootstrap Ignition Config...
    DEBU[0000] Generating dependencies of Bootstrap Ignition Config...
    INFO[0000]   Fetching Install Config...
    DEBU[0000]   Generating dependencies of Install Config...
    INFO[0000]     Fetching Cluster ID...
    DEBU[0000]     Generating Cluster ID...
    INFO[0000]     Fetching Email Address...
    DEBU[0000]     Generating Email Address...

pkg/asset/BUILD.bazel

@@ -11,6 +11,7 @@ go_library(
     ],
     importpath = "github.com/openshift/installer/pkg/asset",
     visibility = ["//visibility:public"],
+    deps = ["//vendor/github.com/Sirupsen/logrus:go_default_library"],
 )
 
 go_test(

pkg/asset/store.go

@@ -1,5 +1,9 @@
 package asset
 
+import (
+	"github.com/Sirupsen/logrus"
+)
+
 // Store is a store for the states of assets.
 type Store interface {
 	// Fetch retrieves the state of the given asset, generating it and its
@@ -15,19 +19,31 @@ type StoreImpl struct {
 // Fetch retrieves the state of the given asset, generating it and its
 // dependencies if necessary.
 func (s *StoreImpl) Fetch(asset Asset) (*State, error) {
+	return s.fetch(asset, "")
+}
+
+func (s *StoreImpl) fetch(asset Asset, indent string) (*State, error) {
+	logrus.Infof("%sFetching %s...", indent, asset.Name())
 	state, ok := s.assets[asset]
 	if ok {
+		logrus.Debugf("%sFound %s...", indent, asset.Name())
 		return state, nil
 	}
-	dependies := asset.Dependencies()
-	dependenciesStates := make(map[Asset]*State, len(dependies))
-	for _, d := range dependies {
-		ds, err := s.Fetch(d)
+
+	dependencies := asset.Dependencies()
+	dependenciesStates := make(map[Asset]*State, len(dependencies))
+	if len(dependencies) > 0 {
+		logrus.Debugf("%sGenerating dependencies of %s...", indent, asset.Name())
+	}
+	for _, d := range dependencies {
+		ds, err := s.fetch(d, indent+"  ")
 		if err != nil {
 			return nil, err
 		}
 		dependenciesStates[d] = ds
 	}
+
+	logrus.Debugf("%sGenerating %s...", indent, asset.Name())
 	state, err := asset.Generate(dependenciesStates)
 	if err != nil {
 		return nil, err