feat: add centos and amazon linux support (#115)

.github/workflows/test-images.json

@@ -52,5 +52,17 @@
         "tag": "2.0.20220527",
         "distro": "Mariner Distroless",
         "description": "Custom rpmmanifest files, no yum/dnf/microdnf/rpm"
+    },
+    {
+        "image": "docker.io/library/centos",
+        "tag": "7.6.1810",
+        "distro": "CentOS",
+        "description": "Valid rpm DB, yum present"
+    },
+    {
+        "image": "docker.io/library/amazonlinux",
+        "tag": "2.0.20210326.0",
+        "distro": "Amazon Linux",
+        "description": "Valid rpm DB, yum present"
     }
 ]

pkg/pkgmgr/pkgmgr.go

@@ -34,13 +34,9 @@ func GetPackageManager(osType string, config *buildkit.Config, workingFolder str
 	switch osType {
 	case "alpine":
 		return &apkManager{config: config, workingFolder: workingFolder}, nil
-	case "debian":
-		fallthrough
-	case "ubuntu":
+	case "debian", "ubuntu":
 		return &dpkgManager{config: config, workingFolder: workingFolder}, nil
-	case "cbl-mariner":
-		fallthrough
-	case "redhat":
+	case "cbl-mariner", "centos", "redhat", "amazon":
 		return &rpmManager{config: config, workingFolder: workingFolder}, nil
 	default:
 		return nil, fmt.Errorf("unsupported osType %s specified", osType)

pkg/pkgmgr/rpm.go

@@ -256,9 +256,10 @@ func (rm *rpmManager) probeRPMStatus(ctx context.Context, toolImage string) erro
 	outStatePath := filepath.Join(rm.workingFolder, resultsPath)
 	rpmDB := getRPMDBType(outStatePath)
 	log.Debugf("RPM DB Type in image is: %s", rpmDB)
-	if rpmDB == RPMDBManifests {
+	switch rpmDB {
+	case RPMDBManifests:
 		rm.isDistroless = true
-	} else if rpmDB == RPMDBNone || rpmDB == RPMDBMixed {
+	case RPMDBNone, RPMDBMixed:
 		err := fmt.Errorf("could not find determine RPM DB type of target image: %v", rpmDB)
 		log.Error(err)
 		return err