etcdctl: add command to generate shell completion

To improve the UX of etcdctl. Completion is generated by cobra
according to defined commands and flags.

Fixes #13111

etcdctl/ctlv3/command/check.go

@@ -130,6 +130,9 @@ func NewCheckPerfCommand() *cobra.Command {
 	cmd.Flags().StringVar(&checkPerfPrefix, "prefix", "/etcdctl-check-perf/", "The prefix for writing the performance check's keys.")
 	cmd.Flags().BoolVar(&autoCompact, "auto-compact", false, "Compact storage with last revision after test is finished.")
 	cmd.Flags().BoolVar(&autoDefrag, "auto-defrag", false, "Defragment storage after test is finished.")
+	cmd.RegisterFlagCompletionFunc("load", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+		return []string{"small", "medium", "large", "xLarge"}, cobra.ShellCompDirectiveDefault
+	})
 
 	return cmd
 }

etcdctl/ctlv3/command/completion_command.go

@@ -0,0 +1,84 @@
+// Copyright 2021 The etcd 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 command
+
+import (
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+func NewCompletionCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "completion [bash|zsh|fish|powershell]",
+		Short: "Generate completion script",
+		Long: `To load completions:
+
+Bash:
+
+  $ source <(etcdctl completion bash)
+
+  # To load completions for each session, execute once:
+  # Linux:
+  $ etcdctl completion bash > /etc/bash_completion.d/etcdctl
+  # macOS:
+  $ etcdctl completion bash > /usr/local/etc/bash_completion.d/etcdctl
+
+Zsh:
+
+  # If shell completion is not already enabled in your environment,
+  # you will need to enable it.  You can execute the following once:
+
+  $ echo "autoload -U compinit; compinit" >> ~/.zshrc
+
+  # To load completions for each session, execute once:
+  $ etcdctl completion zsh > "${fpath[1]}/_etcdctl"
+
+  # You will need to start a new shell for this setup to take effect.
+
+fish:
+
+  $ etcdctl completion fish | source
+
+  # To load completions for each session, execute once:
+  $ etcdctl completion fish > ~/.config/fish/completions/etcdctl.fish
+
+PowerShell:
+
+  PS> etcdctl completion powershell | Out-String | Invoke-Expression
+
+  # To load completions for every new session, run:
+  PS> etcdctl completion powershell > etcdctl.ps1
+  # and source this file from your PowerShell profile.
+`,
+		DisableFlagsInUseLine: true,
+		ValidArgs:             []string{"bash", "zsh", "fish", "powershell"},
+		Args:                  cobra.ExactValidArgs(1),
+		Run: func(cmd *cobra.Command, args []string) {
+			switch args[0] {
+			case "bash":
+				cmd.Root().GenBashCompletion(os.Stdout)
+			case "zsh":
+				cmd.Root().GenZshCompletion(os.Stdout)
+			case "fish":
+				cmd.Root().GenFishCompletion(os.Stdout, true)
+			case "powershell":
+				cmd.Root().GenPowerShellCompletionWithDesc(os.Stdout)
+			}
+		},
+	}
+
+	return cmd
+}

etcdctl/ctlv3/command/defrag_command.go

@@ -36,6 +36,7 @@ func NewDefragCommand() *cobra.Command {
 	}
 	cmd.PersistentFlags().BoolVar(&epClusterEndpoints, "cluster", false, "use all endpoints from the cluster member list")
 	cmd.Flags().StringVar(&defragDataDir, "data-dir", "", "Optional. If present, defragments a data directory not in use by etcd.")
+	cmd.MarkFlagDirname("data-dir")
 	return cmd
 }
 

etcdctl/ctlv3/command/get_command.go

@@ -54,6 +54,17 @@ func NewGetCommand() *cobra.Command {
 	cmd.Flags().BoolVar(&getKeysOnly, "keys-only", false, "Get only the keys")
 	cmd.Flags().BoolVar(&getCountOnly, "count-only", false, "Get only the count")
 	cmd.Flags().BoolVar(&printValueOnly, "print-value-only", false, `Only write values when using the "simple" output format`)
+
+	cmd.RegisterFlagCompletionFunc("consistency", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+		return []string{"l", "s"}, cobra.ShellCompDirectiveDefault
+	})
+	cmd.RegisterFlagCompletionFunc("order", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+		return []string{"ASCEND", "DESCEND"}, cobra.ShellCompDirectiveDefault
+	})
+	cmd.RegisterFlagCompletionFunc("sort-by", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+		return []string{"CREATE", "KEY", "MODIFY", "VALUE", "VERSION"}, cobra.ShellCompDirectiveDefault
+	})
+
 	return cmd
 }
 

etcdctl/ctlv3/command/put_command.go

@@ -20,7 +20,7 @@ import (
 	"strconv"
 
 	"github.com/spf13/cobra"
-	"go.etcd.io/etcd/client/v3"
+	clientv3 "go.etcd.io/etcd/client/v3"
 	"go.etcd.io/etcd/pkg/v3/cobrautl"
 )
 

etcdctl/ctlv3/command/snapshot_command.go

@@ -88,6 +88,8 @@ func NewSnapshotRestoreCommand() *cobra.Command {
 	cmd.Flags().StringVar(&restorePeerURLs, "initial-advertise-peer-urls", defaultInitialAdvertisePeerURLs, "List of this member's peer URLs to advertise to the rest of the cluster")
 	cmd.Flags().StringVar(&restoreName, "name", defaultName, "Human-readable name for this member")
 	cmd.Flags().BoolVar(&skipHashCheck, "skip-hash-check", false, "Ignore snapshot integrity hash value (required if copied from data directory)")
+	cmd.MarkFlagDirname("data-dir")
+	cmd.MarkFlagDirname("wal-dir")
 
 	return cmd
 }

etcdctl/ctlv3/ctl.go

@@ -53,6 +53,9 @@ func init() {
 
 	rootCmd.PersistentFlags().StringVarP(&globalFlags.OutputFormat, "write-out", "w", "simple", "set the output format (fields, json, protobuf, simple, table)")
 	rootCmd.PersistentFlags().BoolVar(&globalFlags.IsHex, "hex", false, "print byte strings as hex encoded strings")
+	rootCmd.RegisterFlagCompletionFunc("write-out", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+		return []string{"fields", "json", "protobuf", "simple", "table"}, cobra.ShellCompDirectiveDefault
+	})
 
 	rootCmd.PersistentFlags().DurationVar(&globalFlags.DialTimeout, "dial-timeout", defaultDialTimeout, "dial timeout for client connections")
 	rootCmd.PersistentFlags().DurationVar(&globalFlags.CommandTimeOut, "command-timeout", defaultCommandTimeOut, "timeout for short running command (excluding dial timeout)")
@@ -93,6 +96,7 @@ func init() {
 		command.NewUserCommand(),
 		command.NewRoleCommand(),
 		command.NewCheckCommand(),
+		command.NewCompletionCommand(),
 	)
 }