Kubeconf builder to return single cluster kubeconf

Now if clusterName is specified for kubebuilder, Build() method
will return kubeconfig containing only context for that cluster.
If no clusterName is specified kubeconfig will have contexts of
all clusters that builder can build. This behaviour is similar
to `kubeconfig get` command.

Relates-To: #460

Change-Id: Ib3bebf61bc60430d347ded41b2e31249b11126eb

pkg/k8s/kubeconfig/builder.go

@@ -97,8 +97,29 @@ func (b *Builder) Build() Interface {
 }
 
 func (b *Builder) build() ([]byte, error) {
+	// Set current context to clustername if it was provided
+	var result *api.Config
+	var err error
+	var kubeContext string
+	if b.clusterName != "" {
+		kubeContext, result, err = b.buildOne(b.clusterName)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		result, err = b.builtSiteKubeconf()
+		if err != nil {
+			return nil, err
+		}
+	}
+	b.siteKubeconf.CurrentContext = kubeContext
+	return clientcmd.Write(*result)
+}
+
+func (b *Builder) builtSiteKubeconf() (*api.Config, error) {
+	log.Debugf("Getting site kubeconfig")
 	for _, clusterID := range b.clusterMap.AllClusters() {
-		log.Printf("Getting kubeconfig for cluster '%s'", clusterID)
+		log.Debugf("Getting kubeconfig for cluster '%s' to build site kubeconfig", clusterID)
 		// buildOne merges context into site kubeconfig
 		_, _, err := b.buildOne(clusterID)
 		if IsErrAllSourcesFailedErr(err) {
@@ -109,15 +130,7 @@ func (b *Builder) build() ([]byte, error) {
 			return nil, err
 		}
 	}
-	// Set current context to clustername if it was provided
+	return b.siteKubeconf, nil
-	if b.clusterName != "" {
-		kubeContext, err := b.clusterMap.ClusterKubeconfigContext(b.clusterName)
-		if err != nil {
-			return nil, err
-		}
-		b.siteKubeconf.CurrentContext = kubeContext
-	}
-	return clientcmd.Write(*b.siteKubeconf)
 }
 
 func (b *Builder) buildOne(clusterID string) (string, *api.Config, error) {

pkg/k8s/kubeconfig/builder_test.go

@@ -101,7 +101,6 @@ func TestBuilderClusterctl(t *testing.T) {
 	}{
 		{
 			name:              "success cluster-api not reachable",
-			requestedClusterName: childClusterID,
 			expectedContexts:  []string{parentClusterID},
 			expectedClusters:  []string{parentParentCluster},
 			expectedAuthInfos: []string{parentParentUser},

pkg/phase/client.go

@@ -102,7 +102,6 @@ func (p *phase) Executor() (ifc.Executor, error) {
 	kubeconf := kubeconfig.NewBuilder().
 		WithBundle(p.helper.PhaseBundleRoot()).
 		WithClusterMap(cMap).
-		WithClusterName(p.apiObj.ClusterName).
 		WithTempRoot(wd).
 		WithClusterctClient(cctlClient).
 		Build()