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tracerunner.go
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tracerunner.go
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package cmd
import (
"context"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"os/signal"
"path"
"strconv"
"strings"
"syscall"
"time"
"github.com/iovisor/kubectl-trace/pkg/downloader"
"github.com/iovisor/kubectl-trace/pkg/procfs"
"github.com/iovisor/kubectl-trace/pkg/pty"
"github.com/iovisor/kubectl-trace/pkg/tracejob"
"github.com/iovisor/kubectl-trace/pkg/upload"
"github.com/spf13/cobra"
)
// A pidDescriber produces some meaningful description of a PID from
// the /proc subtree corresponding to that PID
type pidDescriber func(string) (string, error)
// postProcessor is a function that describes the command to run after a trace
// has completed successfully
type postProcessor func() (string, []string, error)
const (
// MetadataDir is where trace-runner will output traces and metadata
MetadataDir = "/tmp/kubectl-trace"
bpftrace = "bpftrace"
bcc = "bcc"
rbspy = "rbspy"
fake = "fake"
)
var (
bpfTraceBinaryPath = "/usr/bin/bpftrace"
bccToolsDir = "/usr/share/bcc/tools/"
fakeToolsDir = "/usr/share/fake/"
)
type outputType string
const (
stdout outputType = "stdout"
download outputType = "download"
gcs outputType = "gs"
)
type TraceRunnerOptions struct {
// The tracing system to use.
// tracer = bpftrace | bcc | rbspy | fake
tracer string
podUID string
containerID string
// Process selector (similar to a label query) that identifies process to be traced.
// processSelector = label '=' value [',' labelN '=' valueN ...]
// Currently supported labels:
// - pid
// Select a process by its PID in the container namespace. If the value is numeric, select
// the host PID corresponding to that specific container PID. If the value is "last", select
// the host PID with the largest container PID value, optionally filtered by the other
// selectors below.
// - exe
// Filter the process list by matching on the value of /proc/<pid>/exe
// - comm
// Filter the process list by matching on the contents of /proc/<pid>/comm
// - cmdline
// Filter the process list by matching on the contents of /proc/<pid>/cmdline
processSelector string
// Where will the tracing system send output.
// output = stdout | download | file:///path | URI
output string
// In the case of bcc the name of the bcc program to execute.
// In the case of bpftrace the path to contents of the user provided expression or program.
program string
// In the case of bcc the user provided arguments to pass on to program.
// Not used for bpftrace.
programArgs []string
// Values populated after validation
parsedSelector *tracejob.ProcessSelector
outputType outputType
}
func NewTraceRunnerOptions() *TraceRunnerOptions {
return &TraceRunnerOptions{}
}
func NewTraceRunnerCommand() *cobra.Command {
o := NewTraceRunnerOptions()
cmd := &cobra.Command{
PreRunE: func(c *cobra.Command, args []string) error {
return o.Validate(c, args)
},
RunE: func(c *cobra.Command, args []string) error {
if err := o.Complete(c, args); err != nil {
return err
}
if err := o.Run(); err != nil {
fmt.Fprintln(os.Stdout, err.Error())
return err
}
return nil
},
}
cmd.Flags().StringVar(&o.tracer, "tracer", "bpftrace", "Tracing system to use")
cmd.Flags().StringVar(&o.podUID, "pod-uid", "", "UID of target pod")
cmd.Flags().StringVar(&o.containerID, "container-id", "", "ID of target container")
cmd.Flags().StringVar(&o.processSelector, "process-selector", "", "Process Selector (similar to a label query) to filter on")
cmd.Flags().StringVar(&o.output, "output", "stdout", "Where to send tracing output (stdout or local path)")
cmd.Flags().StringVar(&o.program, "program", "/programs/program.bt", "Tracer input script or executable")
cmd.Flags().StringArrayVar(&o.programArgs, "args", o.programArgs, "Arguments to pass through to executable in --program")
return cmd
}
func (o *TraceRunnerOptions) Validate(cmd *cobra.Command, args []string) error {
switch o.tracer {
case bpftrace, bcc, rbspy, fake:
default:
return fmt.Errorf("unknown tracer %s", o.tracer)
}
if len(o.output) == 0 {
return fmt.Errorf("output cannot be empty when specified")
}
switch {
case o.output == "stdout":
o.outputType = stdout
case o.output[0] == '/' || o.output[0] == '.':
o.outputType = download
case strings.HasPrefix(o.output, "gs://"):
o.outputType = gcs
default:
return fmt.Errorf("unknown output %s", o.output)
}
parsed, err := tracejob.NewProcessSelector(o.processSelector)
if err != nil {
return fmt.Errorf(err.Error())
}
o.parsedSelector = parsed
// TODO: unify this logic with run.go in a central selector validator?
switch o.tracer {
case bpftrace, bcc:
case fake:
if _, ok := o.parsedSelector.Pid(); !ok {
return fmt.Errorf(pidProcessSelectorRequiredForTracer, fake)
}
case rbspy:
if _, ok := o.parsedSelector.Pid(); !ok {
return fmt.Errorf(pidProcessSelectorRequiredForTracer, rbspy)
}
default:
panic("We shouldn't get here; have you accounted for all tracer types?")
}
return nil
}
// Complete completes the setup of the command.
func (o *TraceRunnerOptions) Complete(cmd *cobra.Command, args []string) error {
return nil
}
func (o *TraceRunnerOptions) Run() error {
var err error
var binary *string
var args []string
var pp postProcessor
switch o.tracer {
case bpftrace:
binary, args, err = o.prepBpfTraceCommand()
case bcc:
binary, args, err = o.prepBccCommand()
case rbspy:
binary, args, pp, err = o.prepRbspyCommand()
case fake:
binary, args, err = o.prepFakeCommand()
}
if err != nil {
return err
}
// Assume output is stdout until other backends are implemented.
fmt.Println("if your program has maps to print, send a SIGINT using Ctrl-C, if you want to interrupt the execution send SIGINT two times")
ctx, cancel := context.WithCancel(context.Background())
sigCh := make(chan os.Signal, 1)
signal.Notify(sigCh, os.Signal(syscall.SIGINT))
go func() {
killable := false
defer cancel()
for {
select {
case <-ctx.Done():
return
case <-sigCh:
if !killable {
killable = true
fmt.Println("\nfirst SIGINT received, now if your program had maps and did not free them it should print them out")
continue
}
return
}
}
}()
var c *exec.Cmd
if len(args) == 0 {
c = exec.CommandContext(ctx, *binary)
} else {
c = exec.CommandContext(ctx, *binary, args...)
}
err = runTraceCommand(c, o.outputType != stdout)
if pp != nil {
binary, args, err := pp()
if err != nil {
return fmt.Errorf("failed to determine post processor command for tracer %s %v", o.tracer, err)
} else {
fmt.Printf("Running post processor %s %v \n", binary, args)
postProcess := exec.Command(binary, args...)
err = runTraceCommand(postProcess, o.outputType != stdout)
if err != nil {
return fmt.Errorf("failed to execute post processor command for tracer %s %v", o.tracer, err)
}
}
}
switch o.outputType {
case stdout:
return err
case download:
fmt.Println("waiting for trace output to be uploaded")
return signalUploader()
case gcs:
client, err := upload.NewGcsUploader(upload.GcsUploaderOptions{})
if err != nil {
return err
}
fmt.Println("Uploading trace output to " + o.output)
return client.Upload(MetadataDir, o.output)
}
return nil
}
// This helper will ensure that the output for the command is handled correctly,
// either streaming to stdout or teeing to a long file as well.
func runTraceCommand(c *exec.Cmd, streamOutput bool) error {
c.Stdin = os.Stdin
if streamOutput {
outLog, err := os.OpenFile(path.Join(MetadataDir, "stdout.log"), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
if err != nil {
return fmt.Errorf("failed to open stdout log file: %v", err)
}
// Note that this is necessary since kubectl-trace runs with a TTY
// We need to run the trace-runner under a PTY if we want to tee the output
// or else the output will be delayed and in large chunks rather than a stream
f, err := pty.Start(c)
if err != nil {
return fmt.Errorf("failed to start trace runner with pty: %v", err)
}
w := io.MultiWriter(os.Stdout, outLog)
io.Copy(w, f)
defer outLog.Close()
return nil
} else {
c.Stdout = os.Stdout
c.Stderr = os.Stderr
return c.Run()
}
}
func (o *TraceRunnerOptions) prepBpfTraceCommand() (*string, []string, error) {
programPath := o.program
// Render $container_pid to actual process pid if scoped to container.
if o.podUID != "" && o.containerID != "" {
pid, err := o.findTargetPidForPod()
if err != nil {
return nil, nil, err
}
f, err := ioutil.ReadFile(programPath)
if err != nil {
return nil, nil, err
}
programPath = path.Join(os.TempDir(), "program-container.bt")
r := strings.Replace(string(f), "$container_pid", pid, -1)
if err := ioutil.WriteFile(programPath, []byte(r), 0755); err != nil {
return nil, nil, err
}
}
return &bpfTraceBinaryPath, []string{programPath}, nil
}
func (o *TraceRunnerOptions) prepBccCommand() (*string, []string, error) {
// Sanitize o.program by removing common prefix/suffixes.
name := o.program
name = strings.TrimPrefix(name, "/usr/bin/")
name = strings.TrimPrefix(name, "/usr/sbin/")
name = strings.TrimSuffix(name, "-bpfcc")
program := bccToolsDir + name
args := append([]string{}, o.programArgs...)
if o.podUID != "" && o.containerID != "" {
pid, err := o.findTargetPidForPod()
if err != nil {
return nil, nil, err
}
for i, arg := range args {
args[i] = strings.Replace(arg, "$container_pid", pid, -1)
}
}
return &program, args, nil
}
func (o *TraceRunnerOptions) prepRbspyCommand() (*string, []string, postProcessor, error) {
program := rbspy
args := []string{"record", "--format", "speedscope", "--file", path.Join(MetadataDir, "profile.speedscope.json"), "--raw-file", path.Join(MetadataDir, "rbspy.raw.gz"), "--pid"}
foundPid, err := findHostPid(o.podUID, o.containerID, o.parsedSelector)
if err != nil {
return nil, nil, nil, err
}
args = append(args, foundPid)
return &program, args, o.prepRbspyPostprocessCommand, nil
}
func (o *TraceRunnerOptions) prepRbspyPostprocessCommand() (string, []string, error) {
program := rbspy
args := []string{"report", "--format", "flamegraph", "--input", path.Join(MetadataDir, "rbspy.raw.gz"), "--output", path.Join(MetadataDir, "flamegraph.svg")}
return program, args, nil
}
func (o *TraceRunnerOptions) prepFakeCommand() (*string, []string, error) {
name := path.Base(o.program)
program := fakeToolsDir + name
args := append([]string{}, o.programArgs...)
foundPid, err := findHostPid(o.podUID, o.containerID, o.parsedSelector)
if err != nil {
return nil, nil, err
}
for i, arg := range args {
args[i] = strings.Replace(arg, "$target_pid", foundPid, -1)
}
return &program, args, nil
}
func (o *TraceRunnerOptions) findTargetPidForPod() (string, error) {
var pid string
var err error
if o.processSelector != "" {
pid, err = findHostPid(o.podUID, o.containerID, o.parsedSelector)
if err != nil {
return "", err
}
} else {
pid, err = procfs.FindPidByPodContainer(o.podUID, o.containerID)
if err != nil {
return "", err
}
}
return pid, nil
}
func findProcPid(targetPid string, hostPids []string) (string, error) {
for _, pid := range hostPids {
nsPid, err := procfs.GetFinalNamespacePid(pid)
if err != nil {
return "", err
}
if nsPid == targetPid {
return pid, nil
}
}
return "", fmt.Errorf("pid %s not found; is it still running?", targetPid)
}
func findHostPid(podUID, containerID string, selector *tracejob.ProcessSelector) (string, error) {
containerPid, err := procfs.FindPidByPodContainer(podUID, containerID)
if err != nil {
return "", err
}
hostPidsForContainer, err := procfs.FindPidsForContainer(containerPid)
if err != nil {
return "", err
}
foundPid := ""
targetPid, _ := selector.Pid()
if targetPid != "last" {
foundPid, err = findProcPid(targetPid, hostPidsForContainer)
if err != nil {
return "", err
}
} else {
filteredPids, err := filterPidsBySelector(selector, hostPidsForContainer)
if err != nil {
return "", err
}
if len(filteredPids) == 0 {
return "", fmt.Errorf("process matching '%s' not found; is it still running?", selector)
}
foundPid, err = findLastContainerPid(filteredPids)
if err != nil {
return "", err
}
}
return foundPid, nil
}
func filterPidsBySelector(selector *tracejob.ProcessSelector, hostPids []string) ([]string, error) {
matching := hostPids
var err error
targetExe, ok := selector.Exe()
if ok {
matching, err = findPidsMatching(targetExe, matching, procfs.GetProcExe)
if err != nil {
return nil, err
}
}
targetComm, ok := selector.Comm()
if ok {
matching, err = findPidsMatching(targetComm, matching, procfs.GetProcComm)
if err != nil {
return nil, err
}
}
targetCmdline, ok := selector.Cmdline()
if ok {
matching, err = findPidsMatching(targetCmdline, matching, procfs.GetProcCmdline)
if err != nil {
return nil, err
}
}
return matching, nil
}
func findLastContainerPid(hostPids []string) (string, error) {
desiredHostPid := ""
maxNsPid := -1
for _, currentHostPid := range hostPids {
p, err := procfs.GetFinalNamespacePid(currentHostPid)
if err != nil {
return "", err
}
currentNsPid, err := strconv.Atoi(p)
if err != nil {
return "", err
}
if currentNsPid > maxNsPid {
maxNsPid = currentNsPid
desiredHostPid = currentHostPid
}
}
if desiredHostPid == "" {
panic("We shouldn't get here; there must be at least one max PID!")
}
return desiredHostPid, nil
}
func findPidsMatching(needle string, hostPids []string, describePid pidDescriber) ([]string, error) {
matching := []string{}
for _, pid := range hostPids {
desc, err := describePid(pid)
if err != nil {
return nil, err
}
if strings.Contains(desc, needle) {
matching = append(matching, pid)
}
}
return matching, nil
}
func signalUploader() error {
// Signal uploader and wait for it to finish.
b, err := ioutil.ReadFile(downloader.PidFile)
if err != nil {
return err
}
pid, err := strconv.Atoi(string(b))
if err != nil {
return err
}
uploader, err := os.FindProcess(pid)
if err != nil {
return err
}
err = uploader.Signal(os.Interrupt)
if err != nil {
return err
}
// uploader.Wait() doesn't work if the process isn't a child
// so watch in a loop.
for {
time.Sleep(1 * time.Second)
err = uploader.Signal(os.Interrupt)
// err mean process no longer exists
if err != nil {
break
}
}
return nil
}