feat(pkg): Recognize the --label flag when packaging a kernel

Signed-off-by: Alexander Jung <alex@unikraft.io>

Author: nderjung

internal/cli/kraft/pkg/packager_cli_kernel.go

@@ -76,6 +76,18 @@ func (p *packagerCliKernel) Pack(ctx context.Context, opts *PkgOptions, args ...
 		opts.Env = append(opts.Env, envs...)
 	}
 
+	labels := make(map[string]string)
+	if len(opts.Labels) > 0 {
+		for _, label := range opts.Labels {
+			kv := strings.SplitN(label, "=", 2)
+			if len(kv) != 2 {
+				return nil, fmt.Errorf("invalid label format: %s", label)
+			}
+
+			labels[kv[0]] = kv[1]
+		}
+	}
+
 	var result []pack.Package
 	norender := log.LoggerTypeFromString(config.G[config.KraftKit](ctx).Log.Type) != log.FANCY
 
@@ -96,6 +108,7 @@ func (p *packagerCliKernel) Pack(ctx context.Context, opts *PkgOptions, args ...
 					packmanager.PackKConfig(!opts.NoKConfig),
 					packmanager.PackName(opts.Name),
 					packmanager.PackOutput(opts.Output),
+					packmanager.PackLabels(labels),
 				)
 
 				envs := opts.aggregateEnvs()