Add aptlayer analyzer

This commit implements layer analysis for single version package analyzer for
images based on apt package manager

Author: davidcassany

cmd/root.go

@@ -268,7 +268,7 @@ func getExtractPathForName(name string) (string, error) {
 
 func includeLayers() bool {
 	for _, t := range types {
-		if t == "layer" {
+		if strings.Contains(t, "layer") {
 			return true
 		}
 	}

differs/apt_diff.go

@@ -28,6 +28,9 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+//APT package database location
+const dpkgStatusFile string = "var/lib/dpkg/status"
+
 type AptAnalyzer struct {
 }
 
@@ -53,7 +56,7 @@ func (a AptAnalyzer) getPackages(image pkgutil.Image) (map[string]util.PackageIn
 		// invalid image directory path
 		return packages, err
 	}
-	statusFile := filepath.Join(path, "var/lib/dpkg/status")
+	statusFile := filepath.Join(path, dpkgStatusFile)
 	if _, err := os.Stat(statusFile); err != nil {
 		// status file does not exist in this layer
 		return packages, nil
@@ -120,3 +123,61 @@ func parseLine(text string, currPackage string, packages map[string]util.Package
 	}
 	return currPackage
 }
+
+type AptLayerAnalyzer struct {
+}
+
+func (a AptLayerAnalyzer) Name() string {
+	return "AptLayerAnalyzer"
+}
+
+// AptDiff compares the packages installed by apt-get.
+func (a AptLayerAnalyzer) Diff(image1, image2 pkgutil.Image) (util.Result, error) {
+	diff, err := singleVersionLayerDiff(image1, image2, a)
+	return diff, err
+}
+
+func (a AptLayerAnalyzer) Analyze(image pkgutil.Image) (util.Result, error) {
+	analysis, err := singleVersionLayerAnalysis(image, a)
+	return analysis, err
+}
+
+func (a AptLayerAnalyzer) getPackages(image pkgutil.Image) ([]map[string]util.PackageInfo, error) {
+	var packages []map[string]util.PackageInfo
+	if _, err := os.Stat(image.FSPath); err != nil {
+		// invalid image directory path
+		return packages, err
+	}
+	statusFile := filepath.Join(image.FSPath, dpkgStatusFile)
+	if _, err := os.Stat(statusFile); err != nil {
+		// status file does not exist in this image
+		return packages, nil
+	}
+	for _, layer := range image.Layers {
+		layerPackages := make(map[string]util.PackageInfo)
+		if _, err := os.Stat(layer.FSPath); err != nil {
+			// invalid layer directory path
+			return packages, err
+		}
+		statusFile := filepath.Join(layer.FSPath, dpkgStatusFile)
+		if _, err := os.Stat(statusFile); err == nil {
+			// this layer has a package database
+			if file, err := os.Open(statusFile); err == nil {
+				// make sure it gets closed
+				defer file.Close()
+
+				// create a new scanner and read the file line by line
+				scanner := bufio.NewScanner(file)
+				var currPackage string
+				for scanner.Scan() {
+					currPackage = parseLine(scanner.Text(), currPackage, layerPackages)
+				}
+			} else {
+				return packages, err
+			}
+		}
+		packages = append(packages, layerPackages)
+	}
+
+	return packages, nil
+}

differs/differs.go

@@ -47,6 +47,7 @@ var Analyzers = map[string]Analyzer{
 	"file":     FileAnalyzer{},
 	"layer":    FileLayerAnalyzer{},
 	"apt":      AptAnalyzer{},
+	"aptlayer": AptLayerAnalyzer{},
 	"rpm":      RPMAnalyzer{},
 	"pip":      PipAnalyzer{},
 	"node":     NodeAnalyzer{},