Save the distro information the first time we read /etc/os-release, s…

…o that we end up only reading that file once

Signed-off-by: Natalie Arellano <narellano@vmware.com>

internal/fsutil/os_detection.go

@@ -17,12 +17,14 @@ type Detector interface {
 	HasSystemdFile() bool
 	ReadSystemdFile() (string, error)
 	GetInfo(osReleaseContents string) OSInfo
+	StoredInfo() *OSInfo
 	InfoOnce(logger log.Logger)
 }
 
 // DefaultDetector implements Detector
 type DefaultDetector struct {
 	once sync.Once
+	info *OSInfo
 }
 
 // HasSystemdFile returns true if /etc/os-release exists with contents
@@ -60,9 +62,15 @@ func (d *DefaultDetector) GetInfo(osReleaseContents string) OSInfo {
 			break
 		}
 	}
+	d.info = &ret // store for future use
 	return ret
 }
 
+// StoredInfo returns any OSInfo found during the last call to GetInfo
+func (d *DefaultDetector) StoredInfo() *OSInfo {
+	return d.info
+}
+
 // InfoOnce logs an info message to the provided logger, but only once in the lifetime of the receiving DefaultDetector.
 func (d *DefaultDetector) InfoOnce(logger log.Logger) {
 	d.once.Do(func() {

platform/target_data.go

@@ -92,14 +92,22 @@ func matches(target1, target2 string) bool {
 // GetTargetOSFromFileSystem populates the provided target metadata with information from /etc/os-release
 // if it is available.
 func GetTargetOSFromFileSystem(d fsutil.Detector, tm *files.TargetMetadata, logger log.Logger) {
+	if tm.OS == "" {
+		tm.OS = "linux" // we shouldn't get here, as OS comes from the image config, and OS is always required
+	}
+	if tm.Arch == "" {
+		tm.Arch = runtime.GOARCH // in a future world where we support cross-platform builds, this should be removed
+	}
+
+	if info := d.StoredInfo(); info != nil {
+		if info.Version != "" || info.Name != "" {
+			tm.Distro = &files.OSDistro{Name: info.Name, Version: info.Version}
+		}
+		return
+	}
+
 	d.InfoOnce(logger)
 	if d.HasSystemdFile() {
-		if tm.OS == "" {
-			tm.OS = "linux"
-		}
-		if tm.Arch == "" {
-			tm.Arch = runtime.GOARCH // in a future world where we support cross platform builds, this should be removed
-		}
 		contents, err := d.ReadSystemdFile()
 		if err != nil {
 			logger.Warnf("Encountered error trying to read /etc/os-release file: %s", err.Error())

platform/target_data_test.go

@@ -327,3 +327,7 @@ func (d *mockDetector) GetInfo(osReleaseContents string) fsutil.OSInfo {
 }
 
 func (d *mockDetector) InfoOnce(_ llog.Logger) {}
+
+func (d *mockDetector) StoredInfo() *fsutil.OSInfo {
+	return nil
+}