feat(metadata): Distinguish between userdata and metadata for datasources

datasource/configdrive.go

@@ -18,7 +18,11 @@ func (self *configDrive) ConfigRoot() string {
 	return self.root
 }
 
-func (self *configDrive) Fetch() ([]byte, error) {
+func (self *configDrive) FetchMetadata() ([]byte, error) {
+	return self.readFile("meta_data.json")
+}
+
+func (self *configDrive) FetchUserdata() ([]byte, error) {
 	return self.readFile("user_data")
 }
 

datasource/datasource.go

@@ -2,6 +2,7 @@ package datasource
 
 type Datasource interface {
 	ConfigRoot() string
-	Fetch() ([]byte, error)
+	FetchMetadata() ([]byte, error)
+	FetchUserdata() ([]byte, error)
 	Type() string
 }

datasource/file.go

@@ -16,7 +16,11 @@ func (self *localFile) ConfigRoot() string {
 	return ""
 }
 
-func (self *localFile) Fetch() ([]byte, error) {
+func (self *localFile) FetchMetadata() ([]byte, error) {
+	return []byte{}, nil
+}
+
+func (self *localFile) FetchUserdata() ([]byte, error) {
 	return ioutil.ReadFile(self.path)
 }
 

datasource/metadata_service.go

@@ -14,7 +14,11 @@ func (self *metadataService) ConfigRoot() string {
 	return ""
 }
 
-func (ms *metadataService) Fetch() ([]byte, error) {
+func (self *metadataService) FetchMetadata() ([]byte, error) {
+	return []byte{}, nil
+}
+
+func (ms *metadataService) FetchUserdata() ([]byte, error) {
 	client := pkg.NewHttpClient()
 	return client.Get(ms.url)
 }

datasource/proc_cmdline.go

@@ -26,7 +26,11 @@ func (self *procCmdline) ConfigRoot() string {
 	return ""
 }
 
-func (self *procCmdline) Fetch() ([]byte, error) {
+func (self *procCmdline) FetchMetadata() ([]byte, error) {
+	return []byte{}, nil
+}
+
+func (self *procCmdline) FetchUserdata() ([]byte, error) {
 	contents, err := ioutil.ReadFile(self.Location)
 	if err != nil {
 		return nil, err

datasource/proc_cmdline_test.go

@@ -77,7 +77,7 @@ func TestProcCmdlineAndFetchConfig(t *testing.T) {
 
 	p := NewProcCmdline()
 	p.Location = file.Name()
-	cfg, err := p.Fetch()
+	cfg, err := p.FetchUserdata()
 	if err != nil {
 		t.Errorf("Test produced error: %v", err)
 	}