Merge pull request #223 from fahedouch/setup-nerdctl-top

Setup nerdctl top cmd

Author: AkihiroSuda

README.md

@@ -214,6 +214,8 @@ It does not necessarily mean that the corresponding features are missing in cont
     - [:whale: nerdctl events](#whale-nerdctl-events)
     - [:whale: nerdctl info](#whale-nerdctl-info)
     - [:whale: nerdctl version](#whale-nerdctl-version)
+  - [Stats management](#stats-management)
+    - [:whale: nerdctl top](#whale-nerdctl-top)
   - [Shell completion](#shell-completion)
     - [:nerd_face: nerdctl completion bash](#nerd_face-nerdctl-completion-bash)
   - [Compose](#compose)
@@ -753,6 +755,14 @@ Usage: `nerdctl version [OPTIONS]`
 
 Unimplemented `docker version` flags: `--format`
 
+## Stats management
+### :whale: nerdctl top
+Display the running processes of a container.
+
+
+Usage: `nerdctl top CONTAINER [ps OPTIONS]`
+
+
 ## Shell completion
 
 ### :nerd_face: nerdctl completion bash
@@ -849,7 +859,6 @@ Container management:
 
 Stats:
 - `docker stats`
-- `docker top`
 
 Image:
 - `docker export` and `docker import`

main.go

@@ -173,6 +173,8 @@ func newApp() *cli.App {
 		versionCommand,
 		// Inspect
 		inspectCommand,
+		// stats
+		topCommand,
 		// Management
 		containerCommand,
 		imageCommand,

top.go

@@ -0,0 +1,303 @@
+/*
+   Copyright The containerd 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 main
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os/exec"
+	"regexp"
+	"strconv"
+	"strings"
+	"text/tabwriter"
+
+	"github.com/containerd/containerd"
+	"github.com/containerd/nerdctl/pkg/idutil/containerwalker"
+	"github.com/containerd/nerdctl/pkg/infoutil"
+	"github.com/containerd/nerdctl/pkg/rootlessutil"
+	"github.com/pkg/errors"
+	"github.com/urfave/cli/v2"
+)
+
+// ContainerTopOKBody OK response to ContainerTop operation
+type ContainerTopOKBody struct {
+
+	// Each process running in the container, where each is process
+	// is an array of values corresponding to the titles.
+	//
+	// Required: true
+	Processes [][]string `json:"Processes"`
+
+	// The ps column titles
+	// Required: true
+	Titles []string `json:"Titles"`
+}
+
+var topCommand = &cli.Command{
+	Name:         "top",
+	Usage:        "Display the running processes of a container",
+	ArgsUsage:    "CONTAINER [ps OPTIONS]",
+	Action:       topAction,
+	BashComplete: topBashComplete,
+}
+
+func topAction(clicontext *cli.Context) error {
+
+	if clicontext.NArg() < 1 {
+		return errors.Errorf("requires at least 1 argument")
+	}
+
+	// NOTE: rootless container does not rely on cgroupv1.
+	// more details about possible ways to resolve this concern: #223
+	if rootlessutil.IsRootless() && infoutil.CgroupsVersion() == "1" {
+		return fmt.Errorf("top is not supported for rootless container and cgroupv1")
+	}
+
+	client, ctx, cancel, err := newClient(clicontext)
+	if err != nil {
+		return err
+	}
+	defer cancel()
+
+	walker := &containerwalker.ContainerWalker{
+		Client: client,
+		OnFound: func(ctx context.Context, found containerwalker.Found) error {
+			if err := containerTop(ctx, clicontext, client, found.Container.ID(), strings.Join(clicontext.Args().Tail(), " ")); err != nil {
+				return err
+			}
+			return nil
+		},
+	}
+
+	n, err := walker.Walk(ctx, clicontext.Args().First())
+	if err != nil {
+		return err
+	} else if n == 0 {
+		return errors.Errorf("no such container %s", clicontext.Args().First())
+	}
+	return nil
+}
+
+//function from moby/moby/daemon/top_unix.go
+func appendProcess2ProcList(procList *ContainerTopOKBody, fields []string) {
+	// Make sure number of fields equals number of header titles
+	// merging "overhanging" fields
+	process := fields[:len(procList.Titles)-1]
+	process = append(process, strings.Join(fields[len(procList.Titles)-1:], " "))
+	procList.Processes = append(procList.Processes, process)
+}
+
+//function from moby/moby/daemon/top_unix.go
+// psPidsArg converts a slice of PIDs to a string consisting
+// of comma-separated list of PIDs prepended by "-q".
+// For example, psPidsArg([]uint32{1,2,3}) returns "-q1,2,3".
+func psPidsArg(pids []uint32) string {
+	b := []byte{'-', 'q'}
+	for i, p := range pids {
+		b = strconv.AppendUint(b, uint64(p), 10)
+		if i < len(pids)-1 {
+			b = append(b, ',')
+		}
+	}
+	return string(b)
+}
+
+//function from moby/moby/daemon/top_unix.go
+func validatePSArgs(psArgs string) error {
+	// NOTE: \\s does not detect unicode whitespaces.
+	// So we use fieldsASCII instead of strings.Fields in parsePSOutput.
+	// See https://github.com/docker/docker/pull/24358
+	// nolint: gosimple
+	re := regexp.MustCompile("\\s+([^\\s]*)=\\s*(PID[^\\s]*)")
+	for _, group := range re.FindAllStringSubmatch(psArgs, -1) {
+		if len(group) >= 3 {
+			k := group[1]
+			v := group[2]
+			if k != "pid" {
+				return fmt.Errorf("specifying \"%s=%s\" is not allowed", k, v)
+			}
+		}
+	}
+	return nil
+}
+
+//function from moby/moby/daemon/top_unix.go
+// fieldsASCII is similar to strings.Fields but only allows ASCII whitespaces
+func fieldsASCII(s string) []string {
+	fn := func(r rune) bool {
+		switch r {
+		case '\t', '\n', '\f', '\r', ' ':
+			return true
+		}
+		return false
+	}
+	return strings.FieldsFunc(s, fn)
+}
+
+//function from moby/moby/daemon/top_unix.go
+func hasPid(procs []uint32, pid int) bool {
+	for _, p := range procs {
+		if int(p) == pid {
+			return true
+		}
+	}
+	return false
+}
+
+//function from moby/moby/daemon/top_unix.go
+func parsePSOutput(output []byte, procs []uint32) (*ContainerTopOKBody, error) {
+	procList := &ContainerTopOKBody{}
+
+	lines := strings.Split(string(output), "\n")
+	procList.Titles = fieldsASCII(lines[0])
+
+	pidIndex := -1
+	for i, name := range procList.Titles {
+		if name == "PID" {
+			pidIndex = i
+			break
+		}
+	}
+	if pidIndex == -1 {
+		return nil, fmt.Errorf("Couldn't find PID field in ps output")
+	}
+
+	// loop through the output and extract the PID from each line
+	// fixing #30580, be able to display thread line also when "m" option used
+	// in "docker top" client command
+	preContainedPidFlag := false
+	for _, line := range lines[1:] {
+		if len(line) == 0 {
+			continue
+		}
+		fields := fieldsASCII(line)
+
+		var (
+			p   int
+			err error
+		)
+
+		if fields[pidIndex] == "-" {
+			if preContainedPidFlag {
+				appendProcess2ProcList(procList, fields)
+			}
+			continue
+		}
+		p, err = strconv.Atoi(fields[pidIndex])
+		if err != nil {
+			return nil, fmt.Errorf("Unexpected pid '%s': %s", fields[pidIndex], err)
+		}
+
+		if hasPid(procs, p) {
+			preContainedPidFlag = true
+			appendProcess2ProcList(procList, fields)
+			continue
+		}
+		preContainedPidFlag = false
+	}
+	return procList, nil
+}
+
+// function inspired from moby/moby/daemon/top_unix.go
+// ContainerTop lists the processes running inside of the given
+// container by calling ps with the given args, or with the flags
+// "-ef" if no args are given.  An error is returned if the container
+// is not found, or is not running, or if there are any problems
+// running ps, or parsing the output.
+func containerTop(ctx context.Context, clicontext *cli.Context, client *containerd.Client, id string, psArgs string) error {
+	if psArgs == "" {
+		psArgs = "-ef"
+	}
+
+	if err := validatePSArgs(psArgs); err != nil {
+		return err
+	}
+
+	container, err := client.LoadContainer(ctx, id)
+	if err != nil {
+		return err
+	}
+
+	task, err := container.Task(ctx, nil)
+	if err != nil {
+		return err
+	}
+
+	status, err := task.Status(ctx)
+	if err != nil {
+		return err
+	}
+
+	if status.Status != containerd.Running {
+		return nil
+	}
+
+	//TO DO handle restarting case: wait for container to restart and then launch top command
+
+	procs, err := task.Pids(ctx)
+	if err != nil {
+		return err
+	}
+
+	psList := make([]uint32, 0, len(procs))
+	for _, ps := range procs {
+		psList = append(psList, ps.Pid)
+	}
+
+	args := strings.Split(psArgs, " ")
+	pids := psPidsArg(psList)
+	output, err := exec.Command("ps", append(args, pids)...).Output()
+	if err != nil {
+		// some ps options (such as f) can't be used together with q,
+		// so retry without it
+		output, err = exec.Command("ps", args...).Output()
+		if err != nil {
+			if ee, ok := err.(*exec.ExitError); ok {
+				// first line of stderr shows why ps failed
+				line := bytes.SplitN(ee.Stderr, []byte{'\n'}, 2)
+				if len(line) > 0 && len(line[0]) > 0 {
+					return errors.New(string(line[0]))
+				}
+			}
+			return nil
+		}
+	}
+	procList, err := parsePSOutput(output, psList)
+	if err != nil {
+		return err
+	}
+
+	w := tabwriter.NewWriter(clicontext.App.Writer, 20, 1, 3, ' ', 0)
+	fmt.Fprintln(w, strings.Join(procList.Titles, "\t"))
+
+	for _, proc := range procList.Processes {
+		fmt.Fprintln(w, strings.Join(proc, "\t"))
+	}
+
+	return w.Flush()
+}
+
+func topBashComplete(clicontext *cli.Context) {
+	coco := parseCompletionContext(clicontext)
+	if coco.boring || coco.flagTakesValue {
+		defaultBashComplete(clicontext)
+		return
+	}
+	// show container names (TODO: only running containers)
+	bashCompleteContainerNames(clicontext, nil)
+}

top_test.go

@@ -0,0 +1,42 @@
+/*
+   Copyright The containerd 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 main
+
+import (
+	"testing"
+
+	"github.com/containerd/nerdctl/pkg/infoutil"
+	"github.com/containerd/nerdctl/pkg/rootlessutil"
+	"github.com/containerd/nerdctl/pkg/testutil"
+)
+
+func TestTop(t *testing.T) {
+	//more details https://github.com/containerd/nerdctl/pull/223#issuecomment-851395178
+	if rootlessutil.IsRootless() && infoutil.CgroupsVersion() == "1" {
+		t.Skip("test skipped for rootless container with cgroup v1")
+	}
+	const (
+		testContainerName = "nerdctl-test-top"
+	)
+
+	base := testutil.NewBase(t)
+	defer base.Cmd("rm", "-f", testContainerName).Run()
+
+	base.Cmd("run", "-d", "--name", testContainerName, testutil.AlpineImage, "sleep", "5").AssertOK()
+	base.Cmd("top", testContainerName, "-o", "pid,user,cmd").AssertOK()
+
+}