github.com/opencontainers/runc@v1.2.0-rc.1.0.20240520010911-492dc558cdd6/ps.go (about)

     1  package main
     2  
     3  import (
     4  	"encoding/json"
     5  	"errors"
     6  	"fmt"
     7  	"os"
     8  	"os/exec"
     9  	"strconv"
    10  	"strings"
    11  
    12  	"github.com/sirupsen/logrus"
    13  	"github.com/urfave/cli"
    14  )
    15  
    16  var psCommand = cli.Command{
    17  	Name:      "ps",
    18  	Usage:     "ps displays the processes running inside a container",
    19  	ArgsUsage: `<container-id> [ps options]`,
    20  	Flags: []cli.Flag{
    21  		cli.StringFlag{
    22  			Name:  "format, f",
    23  			Value: "table",
    24  			Usage: `select one of: ` + formatOptions,
    25  		},
    26  	},
    27  	Action: func(context *cli.Context) error {
    28  		if err := checkArgs(context, 1, minArgs); err != nil {
    29  			return err
    30  		}
    31  		rootlessCg, err := shouldUseRootlessCgroupManager(context)
    32  		if err != nil {
    33  			return err
    34  		}
    35  		if rootlessCg {
    36  			logrus.Warn("runc ps may fail if you don't have the full access to cgroups")
    37  		}
    38  
    39  		container, err := getContainer(context)
    40  		if err != nil {
    41  			return err
    42  		}
    43  
    44  		pids, err := container.Processes()
    45  		if err != nil {
    46  			return err
    47  		}
    48  
    49  		switch context.String("format") {
    50  		case "table":
    51  		case "json":
    52  			return json.NewEncoder(os.Stdout).Encode(pids)
    53  		default:
    54  			return errors.New("invalid format option")
    55  		}
    56  
    57  		// [1:] is to remove command name, ex:
    58  		// context.Args(): [container_id ps_arg1 ps_arg2 ...]
    59  		// psArgs:         [ps_arg1 ps_arg2 ...]
    60  		//
    61  		psArgs := context.Args()[1:]
    62  		if len(psArgs) == 0 {
    63  			psArgs = []string{"-ef"}
    64  		}
    65  
    66  		cmd := exec.Command("ps", psArgs...)
    67  		output, err := cmd.CombinedOutput()
    68  		if err != nil {
    69  			return fmt.Errorf("%w: %s", err, output)
    70  		}
    71  
    72  		lines := strings.Split(string(output), "\n")
    73  		pidIndex, err := getPidIndex(lines[0])
    74  		if err != nil {
    75  			return err
    76  		}
    77  
    78  		fmt.Println(lines[0])
    79  		for _, line := range lines[1:] {
    80  			if len(line) == 0 {
    81  				continue
    82  			}
    83  			fields := strings.Fields(line)
    84  			p, err := strconv.Atoi(fields[pidIndex])
    85  			if err != nil {
    86  				return fmt.Errorf("unable to parse pid: %w", err)
    87  			}
    88  
    89  			for _, pid := range pids {
    90  				if pid == p {
    91  					fmt.Println(line)
    92  					break
    93  				}
    94  			}
    95  		}
    96  		return nil
    97  	},
    98  	SkipArgReorder: true,
    99  }
   100  
   101  func getPidIndex(title string) (int, error) {
   102  	titles := strings.Fields(title)
   103  
   104  	pidIndex := -1
   105  	for i, name := range titles {
   106  		if name == "PID" {
   107  			return i, nil
   108  		}
   109  	}
   110  
   111  	return pidIndex, errors.New("couldn't find PID field in ps output")
   112  }