cluster: handle missing clusters correctly

pkg/cluster/cluster.go

@@ -936,10 +936,16 @@ func (c *Controller) Get(ctx context.Context, name string) (*api.Cluster, error)
 	if !ok {
 		return nil, apierrors.NewNotFound(groupResource, name)
 	}
+
+	configCluster, ok := config.Clusters[ct.Cluster]
+	if !ok {
+		return nil, apierrors.NewNotFound(groupResource, name)
+	}
+
 	cluster := &api.Cluster{
 		TypeMeta: typeMeta,
 		Name:     name,
-		Product:  clusterid.ProductFromContext(ct, config.Clusters[ct.Cluster]).String(),
+		Product:  clusterid.ProductFromContext(ct, configCluster).String(),
 	}
 	c.populateCluster(ctx, cluster)
 
@@ -954,7 +960,13 @@ func (c *Controller) List(ctx context.Context, options ListOptions) (*api.Cluste
 
 	config := c.configCopy()
 	names := make([]string, 0, len(c.config.Contexts))
-	for name := range config.Contexts {
+	for name, ct := range config.Contexts {
+		_, ok := config.Clusters[ct.Cluster]
+		if !ok {
+			// Filter out malformed contexts.
+			continue
+		}
+
 		names = append(names, name)
 	}
 	sort.Strings(names)

pkg/cluster/cluster_test.go

@@ -75,6 +75,18 @@ func TestClusterList(t *testing.T) {
 	assert.Equal(t, "microk8s", clusters.Items[1].Name)
 }
 
+// Make sure that an empty config doesn't confuse ctlptl.
+func TestClusterListEmptyConfig(t *testing.T) {
+	c := newFakeController(t)
+	c.config.Contexts["kind"] = &clientcmdapi.Context{}
+
+	clusters, err := c.List(context.Background(), ListOptions{})
+	assert.NoError(t, err)
+	require.Equal(t, 2, len(clusters.Items))
+	assert.Equal(t, "docker-desktop", clusters.Items[0].Name)
+	assert.Equal(t, "microk8s", clusters.Items[1].Name)
+}
+
 func TestClusterListSelectorMatch(t *testing.T) {
 	c := newFakeController(t)
 	clusters, err := c.List(context.Background(), ListOptions{FieldSelector: "product=microk8s"})
@@ -114,6 +126,25 @@ func TestClusterApplyKIND(t *testing.T) {
 	assert.Equal(t, "kind-kind", result.Name)
 }
 
+// Make sure an empty context doesn't confuse ctlptl.
+func TestClusterApplyKINDEmptyConfig(t *testing.T) {
+	f := newFixture(t)
+	f.setOS("darwin")
+
+	f.config.Contexts["kind"] = &clientcmdapi.Context{}
+
+	assert.Equal(t, false, f.d4m.started)
+	kindAdmin := f.newFakeAdmin(clusterid.ProductKIND)
+
+	result, err := f.controller.Apply(context.Background(), &api.Cluster{
+		Product: string(clusterid.ProductKIND),
+	})
+	require.NoError(t, err)
+	assert.Equal(t, true, f.d4m.started)
+	assert.Equal(t, "kind-kind", kindAdmin.created.Name)
+	assert.Equal(t, "kind-kind", result.Name)
+}
+
 func TestClusterApplyFailsToStart(t *testing.T) {
 	f := newFixture(t)
 	f.setOS("darwin")