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// +build linux
package libpod
import (
"bufio"
"os"
"strconv"
"strings"
"github.com/containers/podman/v3/libpod/define"
"github.com/containers/podman/v3/pkg/rootless"
"github.com/containers/psgo"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
// Top gathers statistics about the running processes in a container. It returns a
// []string for output
func (c *Container) Top(descriptors []string) ([]string, error) {
if c.config.NoCgroups {
return nil, errors.Wrapf(define.ErrNoCgroups, "cannot run top on container %s as it did not create a cgroup", c.ID())
}
conStat, err := c.State()
if err != nil {
return nil, errors.Wrapf(err, "unable to look up state for %s", c.ID())
}
if conStat != define.ContainerStateRunning {
return nil, errors.Errorf("top can only be used on running containers")
}
// Also support comma-separated input.
psgoDescriptors := []string{}
for _, d := range descriptors {
for _, s := range strings.Split(d, ",") {
if s != "" {
psgoDescriptors = append(psgoDescriptors, s)
}
}
}
// If we encountered an ErrUnknownDescriptor error, fallback to executing
// ps(1). This ensures backwards compatibility to users depending on ps(1)
// and makes sure we're ~compatible with docker.
output, psgoErr := c.GetContainerPidInformation(psgoDescriptors)
if psgoErr == nil {
return output, nil
}
if !errors.Is(psgoErr, psgo.ErrUnknownDescriptor) {
return nil, psgoErr
}
output, err = c.execPS(descriptors)
if err != nil {
return nil, errors.Wrapf(err, "error executing ps(1) in the container")
}
// Trick: filter the ps command from the output instead of
// checking/requiring PIDs in the output.
filtered := []string{}
cmd := strings.Join(descriptors, " ")
for _, line := range output {
if !strings.Contains(line, cmd) {
filtered = append(filtered, line)
}
}
return filtered, nil
}
// GetContainerPidInformation returns process-related data of all processes in
// the container. The output data can be controlled via the `descriptors`
// argument which expects format descriptors and supports all AIXformat
// descriptors of ps (1) plus some additional ones to for instance inspect the
// set of effective capabilities. Each element in the returned string slice
// is a tab-separated string.
//
// For more details, please refer to github.com/containers/psgo.
func (c *Container) GetContainerPidInformation(descriptors []string) ([]string, error) {
pid := strconv.Itoa(c.state.PID)
// TODO: psgo returns a [][]string to give users the ability to apply
// filters on the data. We need to change the API here
// to return a [][]string if we want to make use of
// filtering.
opts := psgo.JoinNamespaceOpts{FillMappings: rootless.IsRootless()}
psgoOutput, err := psgo.JoinNamespaceAndProcessInfoWithOptions(pid, descriptors, &opts)
if err != nil {
return nil, err
}
res := []string{}
for _, out := range psgoOutput {
res = append(res, strings.Join(out, "\t"))
}
return res, nil
}
// execPS executes ps(1) with the specified args in the container.
func (c *Container) execPS(args []string) ([]string, error) {
rPipe, wPipe, err := os.Pipe()
if err != nil {
return nil, err
}
defer wPipe.Close()
defer rPipe.Close()
rErrPipe, wErrPipe, err := os.Pipe()
if err != nil {
return nil, err
}
defer wErrPipe.Close()
defer rErrPipe.Close()
streams := new(define.AttachStreams)
streams.OutputStream = wPipe
streams.ErrorStream = wErrPipe
streams.AttachOutput = true
streams.AttachError = true
stdout := []string{}
go func() {
scanner := bufio.NewScanner(rPipe)
for scanner.Scan() {
stdout = append(stdout, scanner.Text())
}
}()
stderr := []string{}
go func() {
scanner := bufio.NewScanner(rErrPipe)
for scanner.Scan() {
stderr = append(stderr, scanner.Text())
}
}()
cmd := append([]string{"ps"}, args...)
config := new(ExecConfig)
config.Command = cmd
ec, err := c.Exec(config, streams, nil)
if err != nil {
return nil, err
} else if ec != 0 {
return nil, errors.Errorf("Runtime failed with exit status: %d and output: %s", ec, strings.Join(stderr, " "))
}
if logrus.GetLevel() >= logrus.DebugLevel {
// If we're running in debug mode or higher, we might want to have a
// look at stderr which includes debug logs from conmon.
for _, log := range stderr {
logrus.Debugf("%s", log)
}
}
return stdout, nil
}
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