tiup: support run components without tiup (#2265)

* cmd: add link and unlink

* allow install tiup as other component

* fix

cmd/link.go

@@ -0,0 +1,37 @@
+// Copyright 2021 PingCAP, Inc.
+//
+// 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,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmd
+
+import (
+	"github.com/pingcap/tiup/pkg/environment"
+	"github.com/spf13/cobra"
+)
+
+func newLinkCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "link <component>[:version]",
+		Short: "Link component binary to $TIUP_HOME/bin/",
+		Long:  `[experimental] Link component binary to $TIUP_HOME/bin/`,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			teleCommand = cmd.CommandPath()
+			env := environment.GlobalEnv()
+			if len(args) != 1 {
+				return cmd.Help()
+			}
+			component, version := environment.ParseCompVersion(args[0])
+			return env.Link(component, version)
+		},
+	}
+	return cmd
+}

cmd/root.go

@@ -225,6 +225,8 @@ the latest stable version will be downloaded from the repository.`,
 		newTelemetryCmd(),
 		newEnvCmd(),
 		newHistoryCmd(),
+		newLinkCmd(),
+		newUnlinkCmd(),
 	)
 }
 

cmd/unlink.go

@@ -0,0 +1,53 @@
+// Copyright 2021 PingCAP, Inc.
+//
+// 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,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmd
+
+import (
+	"os"
+	"path/filepath"
+
+	"github.com/pingcap/tiup/pkg/environment"
+	"github.com/pingcap/tiup/pkg/tui"
+	"github.com/spf13/cobra"
+)
+
+func newUnlinkCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "unlink <component>",
+		Short: "Unlink component binary to $TIUP_HOME/bin/",
+		Long:  `[experimental] Unlink component binary in $TIUP_HOME/bin/`,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			teleCommand = cmd.CommandPath()
+			env := environment.GlobalEnv()
+			if len(args) != 1 {
+				return cmd.Help()
+			}
+			component, version := environment.ParseCompVersion(args[0])
+			version, err := env.SelectInstalledVersion(component, version)
+			if err != nil {
+				return err
+			}
+			binPath, err := env.BinaryPath(component, version)
+			if err != nil {
+				return err
+			}
+			target := env.LocalPath("bin", filepath.Base(binPath))
+			if err := tui.PromptForConfirmOrAbortError("%s will be removed.\n Do you want to continue? [y/N]:", target); err != nil {
+				return err
+			}
+			return os.Remove(target)
+		},
+	}
+	return cmd
+}

pkg/environment/env.go

@@ -30,11 +30,6 @@ import (
 	"golang.org/x/mod/semver"
 )
 
-// Name of components
-const (
-	tiupName = "tiup"
-)
-
 var (
 	// ErrInstallFirst indicates that a component/version is not installed
 	ErrInstallFirst = errors.New("component not installed")
@@ -143,9 +138,6 @@ func (env *Environment) UpdateComponents(specs []string, nightly, force bool) er
 	var v1specs []repository.ComponentSpec
 	for _, spec := range specs {
 		component, v := ParseCompVersion(spec)
-		if component == tiupName {
-			continue
-		}
 		if v == "" && nightly {
 			v = utils.NightlyVersionAlias
 		}
@@ -212,6 +204,9 @@ func (env *Environment) SelectInstalledVersion(component string, ver utils.Versi
 	})
 
 	errInstallFirst := errors.Annotatef(ErrInstallFirst, "use `tiup install %s` to install component `%s` first", component, component)
+	if !ver.IsEmpty() {
+		errInstallFirst = errors.Annotatef(ErrInstallFirst, "use `tiup install %s:%s` to install specified version", component, ver.String())
+	}
 
 	if ver.IsEmpty() || string(ver) == utils.NightlyVersionAlias {
 		var selected utils.Version
@@ -290,6 +285,45 @@ func (env *Environment) BinaryPath(component string, ver utils.Version) (string,
 	return env.v1Repo.BinaryPath(installPath, component, ver.String())
 }
 
+// Link add soft link to $TIUP_HOME/bin/
+func (env *Environment) Link(component string, version utils.Version) error {
+	version, err := env.SelectInstalledVersion(component, version)
+	if err != nil {
+		return err
+	}
+	binPath, err := env.BinaryPath(component, version)
+	if err != nil {
+		return err
+	}
+
+	target := env.LocalPath("bin", filepath.Base(binPath))
+	backup := target + ".old"
+	exist := true
+	_, err = os.Stat(target)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return err
+		}
+		exist = false
+	}
+	if exist {
+		if err := os.Rename(target, backup); err != nil {
+			fmt.Printf("Backup of `%s` to `%s` failed.\n", target, backup)
+			return err
+		}
+	}
+
+	fmt.Printf("package %s provides these executables: %s\n", component, filepath.Base(binPath))
+
+	err = os.Symlink(binPath, target)
+	if err != nil {
+		defer func() { _ = os.Rename(backup, target) }()
+	} else {
+		defer func() { _ = os.Remove(backup) }()
+	}
+	return err
+}
+
 // ParseCompVersion parses component part from <component>[:version] specification
 func ParseCompVersion(spec string) (string, utils.Version) {
 	if strings.Contains(spec, ":") {