github.com/flavio/docker@v0.1.3-0.20170117145210-f63d1a6eec47/cmd/docker/daemon_unix.go (about)

     1  // +build daemon
     2  
     3  package main
     4  
     5  import (
     6  	"fmt"
     7  
     8  	"os"
     9  	"os/exec"
    10  	"path/filepath"
    11  	"syscall"
    12  
    13  	"github.com/spf13/cobra"
    14  )
    15  
    16  const daemonBinary = "dockerd"
    17  
    18  func newDaemonCommand() *cobra.Command {
    19  	cmd := &cobra.Command{
    20  		Use:                "daemon",
    21  		Hidden:             true,
    22  		Args:               cobra.ArbitraryArgs,
    23  		DisableFlagParsing: true,
    24  		RunE: func(cmd *cobra.Command, args []string) error {
    25  			return runDaemon()
    26  		},
    27  		Deprecated: "and will be removed in Docker 1.16. Please run `dockerd` directly.",
    28  	}
    29  	cmd.SetHelpFunc(helpFunc)
    30  	return cmd
    31  }
    32  
    33  // CmdDaemon execs dockerd with the same flags
    34  func runDaemon() error {
    35  	// Use os.Args[1:] so that "global" args are passed to dockerd
    36  	return execDaemon(stripDaemonArg(os.Args[1:]))
    37  }
    38  
    39  func execDaemon(args []string) error {
    40  	binaryPath, err := findDaemonBinary()
    41  	if err != nil {
    42  		return err
    43  	}
    44  
    45  	return syscall.Exec(
    46  		binaryPath,
    47  		append([]string{daemonBinary}, args...),
    48  		os.Environ())
    49  }
    50  
    51  func helpFunc(cmd *cobra.Command, args []string) {
    52  	if err := execDaemon([]string{"--help"}); err != nil {
    53  		fmt.Fprintf(os.Stderr, "%s\n", err.Error())
    54  	}
    55  }
    56  
    57  // findDaemonBinary looks for the path to the dockerd binary starting with
    58  // the directory of the current executable (if one exists) and followed by $PATH
    59  func findDaemonBinary() (string, error) {
    60  	execDirname := filepath.Dir(os.Args[0])
    61  	if execDirname != "" {
    62  		binaryPath := filepath.Join(execDirname, daemonBinary)
    63  		if _, err := os.Stat(binaryPath); err == nil {
    64  			return binaryPath, nil
    65  		}
    66  	}
    67  
    68  	return exec.LookPath(daemonBinary)
    69  }
    70  
    71  // stripDaemonArg removes the `daemon` argument from the list
    72  func stripDaemonArg(args []string) []string {
    73  	for i, arg := range args {
    74  		if arg == "daemon" {
    75  			return append(args[:i], args[i+1:]...)
    76  		}
    77  	}
    78  	return args
    79  }