Make datasource.AvailabilityChanges() able to be dynamic so fail out for configdrive mount and url 404's faster

Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au>

config/cloudinit/datasource/configdrive/configdrive.go

@@ -37,13 +37,14 @@ const (
 )
 
 type ConfigDrive struct {
-	root      string
-	readFile  func(filename string) ([]byte, error)
-	lastError error
+	root                string
+	readFile            func(filename string) ([]byte, error)
+	lastError           error
+	availabilityChanges bool
 }
 
 func NewDatasource(root string) *ConfigDrive {
-	return &ConfigDrive{root, ioutil.ReadFile, nil}
+	return &ConfigDrive{root, ioutil.ReadFile, nil, true}
 }
 
 func (cd *ConfigDrive) IsAvailable() bool {
@@ -51,6 +52,8 @@ func (cd *ConfigDrive) IsAvailable() bool {
 		cd.lastError = MountConfigDrive()
 		if cd.lastError != nil {
 			log.Error(cd.lastError)
+			// Don't keep retrying if we can't mount
+			cd.availabilityChanges = false
 			return false
 		}
 		defer cd.Finish()
@@ -58,6 +61,7 @@ func (cd *ConfigDrive) IsAvailable() bool {
 
 	_, cd.lastError = os.Stat(cd.root)
 	return !os.IsNotExist(cd.lastError)
+	// TODO: consider changing IsNotExists to not-available _and_ does not change
 }
 
 func (cd *ConfigDrive) Finish() error {
@@ -72,7 +76,7 @@ func (cd *ConfigDrive) String() string {
 }
 
 func (cd *ConfigDrive) AvailabilityChanges() bool {
-	return true
+	return cd.availabilityChanges
 }
 
 func (cd *ConfigDrive) ConfigRoot() string {
@@ -130,15 +134,13 @@ func (cd *ConfigDrive) tryReadFile(filename string) ([]byte, error) {
 		}
 		defer cd.Finish()
 	}
-	log.Printf("Attempting to read from %q\n", filename)
+	log.Debugf("Attempting to read from %q\n", filename)
 	data, err := cd.readFile(filename)
 	if os.IsNotExist(err) {
 		err = nil
 	}
 	if err != nil {
 		log.Errorf("ERROR read cloud-config file(%s) - err: %q", filename, err)
-	} else {
-		log.Debugf("SUCCESS read cloud-config file(%s) - date: %s", filename, string(data))
 	}
 	return data, err
 }

config/cloudinit/datasource/configdrive/configdrive_test.go

@@ -57,7 +57,7 @@ func TestFetchMetadata(t *testing.T) {
 			},
 		},
 	} {
-		cd := ConfigDrive{tt.root, tt.files.ReadFile, nil}
+		cd := ConfigDrive{tt.root, tt.files.ReadFile, nil, true}
 		metadata, err := cd.FetchMetadata()
 		if err != nil {
 			t.Fatalf("bad error for %+v: want %v, got %q", tt, nil, err)
@@ -91,7 +91,7 @@ func TestFetchUserdata(t *testing.T) {
 			"userdata",
 		},
 	} {
-		cd := ConfigDrive{tt.root, tt.files.ReadFile, nil}
+		cd := ConfigDrive{tt.root, tt.files.ReadFile, nil, true}
 		userdata, err := cd.FetchUserdata()
 		if err != nil {
 			t.Fatalf("bad error for %+v: want %v, got %q", tt, nil, err)
@@ -116,7 +116,7 @@ func TestConfigRoot(t *testing.T) {
 			"/media/configdrive/openstack",
 		},
 	} {
-		cd := ConfigDrive{tt.root, nil, nil}
+		cd := ConfigDrive{tt.root, nil, nil, true}
 		if configRoot := cd.ConfigRoot(); configRoot != tt.configRoot {
 			t.Fatalf("bad config root for %q: want %q, got %q", tt, tt.configRoot, configRoot)
 		}

config/cloudinit/datasource/url/url.go

@@ -46,7 +46,9 @@ func (f *RemoteFile) String() string {
 
 func (f *RemoteFile) AvailabilityChanges() bool {
 	if f.lastError != nil {
-		if _, ok := f.lastError.(pkg.ErrNotFound); ok {
+		// if we have a Network error, then we should retry.
+		// otherwise, we've made a request to the server, and its said nope.
+		if _, ok := f.lastError.(pkg.ErrNetwork); !ok {
 			return false
 		}
 	}