Improve completion for kops root command

cmd/kops/get.go

@@ -28,6 +28,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/kops/cmd/kops/util"
 	api "k8s.io/kops/pkg/apis/kops"
+	"k8s.io/kops/pkg/commands/commandutils"
 	"k8s.io/kops/pkg/kopscodecs"
 	"k8s.io/kubectl/pkg/util/i18n"
 	"k8s.io/kubectl/pkg/util/templates"
@@ -116,7 +117,7 @@ func NewCmdGet(f *util.Factory, out io.Writer) *cobra.Command {
 	return cmd
 }
 
-func RunGet(ctx context.Context, f Factory, out io.Writer, options *GetOptions) error {
+func RunGet(ctx context.Context, f commandutils.Factory, out io.Writer, options *GetOptions) error {
 
 	client, err := f.Clientset()
 	if err != nil {

cmd/kops/get_cluster.go

@@ -31,6 +31,7 @@ import (
 	"k8s.io/kops/cmd/kops/util"
 	kopsapi "k8s.io/kops/pkg/apis/kops"
 	"k8s.io/kops/pkg/apis/kops/registry"
+	"k8s.io/kops/pkg/commands/commandutils"
 	"k8s.io/kops/pkg/kopscodecs"
 	"k8s.io/kops/util/pkg/tables"
 	"k8s.io/kubectl/pkg/util/i18n"
@@ -120,7 +121,7 @@ func NewCmdGetCluster(f *util.Factory, out io.Writer, getOptions *GetOptions) *c
 	return cmd
 }
 
-func RunGetClusters(ctx context.Context, f Factory, out io.Writer, options *GetClusterOptions) error {
+func RunGetClusters(ctx context.Context, f commandutils.Factory, out io.Writer, options *GetClusterOptions) error {
 	client, err := f.Clientset()
 	if err != nil {
 		return err

cmd/kops/root.go

@@ -36,6 +36,7 @@ import (
 	kopsapi "k8s.io/kops/pkg/apis/kops"
 	"k8s.io/kops/pkg/client/simple"
 	"k8s.io/kops/pkg/commands"
+	"k8s.io/kops/pkg/commands/commandutils"
 	"k8s.io/kubectl/pkg/util/i18n"
 	"k8s.io/kubectl/pkg/util/templates"
 )
@@ -65,10 +66,6 @@ var (
 	rootShort = i18n.T(`kOps is Kubernetes Operations.`)
 )
 
-type Factory interface {
-	Clientset() (simple.Clientset, error)
-}
-
 type RootCmd struct {
 	util.FactoryOptions
 
@@ -81,7 +78,7 @@ type RootCmd struct {
 	cobraCommand *cobra.Command
 }
 
-var _ Factory = &RootCmd{}
+var _ commandutils.Factory = &RootCmd{}
 
 var rootCommand = RootCmd{
 	cobraCommand: &cobra.Command{
@@ -129,13 +126,18 @@ func NewCmdRoot(f *util.Factory, out io.Writer) *cobra.Command {
 	cmd.PersistentFlags().StringVar(&rootCommand.configFile, "config", "", "yaml config file (default is $HOME/.kops.yaml)")
 	viper.BindPFlag("config", cmd.PersistentFlags().Lookup("config"))
 	viper.SetDefault("config", "$HOME/.kops.yaml")
+	cmd.RegisterFlagCompletionFunc("config", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return []string{"yaml", "json"}, cobra.ShellCompDirectiveFilterFileExt
+	})
 
 	cmd.PersistentFlags().StringVar(&rootCommand.RegistryPath, "state", "", "Location of state storage (kops 'config' file). Overrides KOPS_STATE_STORE environment variable")
 	viper.BindPFlag("KOPS_STATE_STORE", cmd.PersistentFlags().Lookup("state"))
 	viper.BindEnv("KOPS_STATE_STORE")
+	// TODO implement completion against VFS
 
 	defaultClusterName := os.Getenv("KOPS_CLUSTER_NAME")
 	cmd.PersistentFlags().StringVarP(&rootCommand.clusterName, "name", "", defaultClusterName, "Name of cluster. Overrides KOPS_CLUSTER_NAME environment variable")
+	cmd.RegisterFlagCompletionFunc("name", commandutils.CompleteClusterName(&rootCommand))
 
 	// create subcommands
 	cmd.AddCommand(NewCmdCompletion(f, out))
@@ -290,7 +292,7 @@ func (c *RootCmd) Cluster(ctx context.Context) (*kopsapi.Cluster, error) {
 	return GetCluster(ctx, c.factory, clusterName)
 }
 
-func GetCluster(ctx context.Context, factory Factory, clusterName string) (*kopsapi.Cluster, error) {
+func GetCluster(ctx context.Context, factory commandutils.Factory, clusterName string) (*kopsapi.Cluster, error) {
 	if clusterName == "" {
 		return nil, field.Required(field.NewPath("clusterName"), "Cluster name is required")
 	}

pkg/commands/commandutils/BUILD.bazel

@@ -2,7 +2,19 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
-    srcs = ["exit.go"],
+    srcs = [
+        "cluster.go",
+        "error.go",
+        "exit.go",
+        "factory.go",
+        "klog.go",
+    ],
     importpath = "k8s.io/kops/pkg/commands/commandutils",
     visibility = ["//visibility:public"],
+    deps = [
+        "//pkg/client/simple:go_default_library",
+        "//vendor/github.com/spf13/cobra:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
+        "//vendor/k8s.io/klog/v2:go_default_library",
+    ],
 )

pkg/commands/commandutils/cluster.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package commandutils
+
+import (
+	"context"
+
+	"github.com/spf13/cobra"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+// CompleteClusterName returns a Cobra completion function for cluster names.
+func CompleteClusterName(f Factory) func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+	return func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		ConfigureKlogForCompletion()
+
+		client, err := f.Clientset()
+		if err != nil {
+			return CompletionError("getting clientset", err)
+		}
+
+		list, err := client.ListClusters(context.TODO(), metav1.ListOptions{})
+		if err != nil {
+			return CompletionError("listing clusters", err)
+		}
+
+		var clusterNames []string
+		for _, cluster := range list.Items {
+			clusterNames = append(clusterNames, cluster.Name)
+		}
+
+		return clusterNames, cobra.ShellCompDirectiveNoFileComp
+	}
+}

pkg/commands/commandutils/error.go

@@ -0,0 +1,29 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package commandutils
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+// CompletionError a helper function to logs and return an error from a Cobra completion function.
+func CompletionError(prefix string, err error) ([]string, cobra.ShellCompDirective) {
+	cobra.CompError(fmt.Sprintf("%s: %v", prefix, err))
+	return nil, cobra.ShellCompDirectiveError | cobra.ShellCompDirectiveNoFileComp
+}

pkg/commands/commandutils/factory.go

@@ -0,0 +1,23 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package commandutils
+
+import "k8s.io/kops/pkg/client/simple"
+
+type Factory interface {
+	Clientset() (simple.Clientset, error)
+}

pkg/commands/commandutils/klog.go

@@ -0,0 +1,34 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package commandutils
+
+import (
+	"github.com/spf13/cobra"
+	"k8s.io/klog/v2"
+)
+
+// ConfigureKlogForCompletion configures Klog to not interfere with Cobra completion functions.
+func ConfigureKlogForCompletion() {
+	klog.SetOutput(&toCompDebug{})
+}
+
+type toCompDebug struct{}
+
+func (t toCompDebug) Write(p []byte) (n int, err error) {
+	cobra.CompDebug(string(p), false)
+	return len(p), nil
+}