fix(k8s): add image sources (#4411)

docs/docs/references/configuration/cli/trivy_kubernetes.md

@@ -51,6 +51,7 @@ trivy kubernetes [flags] { cluster | all | specific resources like kubectl. eg:
       --ignore-policy string              specify the Rego file path to evaluate each vulnerability
       --ignore-unfixed                    display only fixed vulnerabilities
       --ignorefile string                 specify .trivyignore file (default ".trivyignore")
+      --image-src strings                 image source(s) to use, in priority order (docker,containerd,podman,remote) (default [docker,containerd,podman,remote])
       --include-non-failures              include successes and exceptions, available with '--scanners config'
       --java-db-repository string         OCI repository to retrieve trivy-java-db from (default "ghcr.io/aquasecurity/trivy-java-db")
       --k8s-version string                specify k8s version to validate outdated api by it (example: 1.21.0)

pkg/commands/app.go

@@ -807,6 +807,9 @@ func NewKubernetesCommand(globalFlags *flag.GlobalFlagGroup) *cobra.Command {
 	)
 	scanFlags.Scanners = &scanners
 
+	// required only SourceFlag
+	imageFlags := &flag.ImageFlagGroup{ImageSources: &flag.SourceFlag}
+
 	reportFlagGroup := flag.NewReportFlagGroup()
 	compliance := flag.ComplianceFlag
 	compliance.Usage += fmt.Sprintf(" (%s,%s, %s, %s)", types.ComplianceK8sNsa, types.ComplianceK8sCIS, types.ComplianceK8sPSSBaseline, types.ComplianceK8sPSSRestricted)
@@ -816,6 +819,7 @@ func NewKubernetesCommand(globalFlags *flag.GlobalFlagGroup) *cobra.Command {
 	k8sFlags := &flag.Flags{
 		CacheFlagGroup:         flag.NewCacheFlagGroup(),
 		DBFlagGroup:            flag.NewDBFlagGroup(),
+		ImageFlagGroup:         imageFlags,
 		K8sFlagGroup:           flag.NewK8sFlagGroup(), // kubernetes-specific flags
 		MisconfFlagGroup:       flag.NewMisconfFlagGroup(),
 		RegoFlagGroup:          flag.NewRegoFlagGroup(),