runservice toolbox: add exec command

cmd/toolbox/cmd/exec.go

@@ -0,0 +1,85 @@
+// Copyright 2019 Sorint.lab
+//
+// 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 cmd
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"syscall"
+
+	"github.com/spf13/cobra"
+)
+
+type ExecData struct {
+	Cmd        []string          `json:"cmd,omitempty"`
+	Env        map[string]string `json:"env,omitempty"`
+	WorkingDir string            `json:"working_dir,omitempty"`
+}
+
+var cmdExec = &cobra.Command{
+	Use:   "exec",
+	Run:   execRun,
+	Short: "executes the provided command using the provided working dir and environment",
+}
+
+type execOptions struct {
+	env        string
+	workingDir string
+}
+
+var execOpts execOptions
+
+func init() {
+	flags := cmdExec.PersistentFlags()
+
+	flags.StringVarP(&execOpts.workingDir, "workingdir", "w", "", "working directory")
+	flags.StringVarP(&execOpts.env, "env", "e", "", "environment (as json object)")
+
+	CmdToolbox.AddCommand(cmdExec)
+}
+
+func execRun(cmd *cobra.Command, args []string) {
+	env := os.Environ()
+	if execOpts.env != "" {
+		envmap := map[string]string{}
+		if err := json.Unmarshal([]byte(execOpts.env), &envmap); err != nil {
+			log.Fatalf("failed to unmarshal env: %v", err)
+		}
+		// also set current env so exec.LookPath will use the provided env
+		for n, v := range envmap {
+			env = append(env, fmt.Sprintf("%s=%s", n, v))
+			if err := os.Setenv(n, v); err != nil {
+				log.Fatalf("failed to set env: %v", err)
+			}
+		}
+	}
+
+	if execOpts.workingDir != "" {
+		if err := os.Chdir(execOpts.workingDir); err != nil {
+			log.Fatalf("failed to change working dir to %q", execOpts.workingDir)
+		}
+	}
+
+	p, err := exec.LookPath(args[0])
+	if err != nil {
+		log.Fatalf("failed to find executable %q: %v", args[0], err)
+	}
+	if err := syscall.Exec(p, args, env); err != nil {
+		log.Fatalf("failed to exec: %v", err)
+	}
+}