package daemon
 
 import (
 	"bytes"
 	"fmt"
 	"runtime"
 	"strings"

 	"sync"

 	"time"
 
 	"golang.org/x/net/context"
 

 	"github.com/docker/docker/api/types"

 	containertypes "github.com/docker/docker/api/types/container"

 	"github.com/docker/docker/api/types/strslice"

 	"github.com/docker/docker/container"
 	"github.com/docker/docker/daemon/exec"

 	"github.com/sirupsen/logrus"

 )
 
 const (
 	// Longest healthcheck probe output message to store. Longer messages will be truncated.
 	maxOutputLen = 4096
 
 	// Default interval between probe runs (from the end of the first to the start of the second).
 	// Also the time before the first probe.
 	defaultProbeInterval = 30 * time.Second
 
 	// The maximum length of time a single probe run should take. If the probe takes longer
 	// than this, the check is considered to have failed.
 	defaultProbeTimeout = 30 * time.Second
 

 	// The time given for the container to start before the health check starts considering
 	// the container unstable. Defaults to none.
 	defaultStartPeriod = 0 * time.Second
 

 	// Default number of consecutive failures of the health check
 	// for the container to be considered unhealthy.
 	defaultProbeRetries = 3
 

 	// Maximum number of entries to record
 	maxLogEntries = 5
 )
 
 const (
 	// Exit status codes that can be returned by the probe command.
 

 	exitStatusHealthy = 0 // Container is healthy

 )
 
 // probe implementations know how to run a particular type of probe.
 type probe interface {
 	// Perform one run of the check. Returns the exit code and an optional
 	// short diagnostic string.
 	run(context.Context, *Daemon, *container.Container) (*types.HealthcheckResult, error)
 }
 
 // cmdProbe implements the "CMD" probe type.
 type cmdProbe struct {
 	// Run the command with the system's default shell instead of execing it directly.
 	shell bool
 }
 
 // exec the healthcheck command in the container.
 // Returns the exit code and probe output (if any)

 func (p *cmdProbe) run(ctx context.Context, d *Daemon, cntr *container.Container) (*types.HealthcheckResult, error) {
 	cmdSlice := strslice.StrSlice(cntr.Config.Healthcheck.Test)[1:]

 	if p.shell {

 		cmdSlice = append(getShell(cntr.Config), cmdSlice...)

 	}
 	entrypoint, args := d.getEntrypointAndArgs(strslice.StrSlice{}, cmdSlice)
 	execConfig := exec.NewConfig()
 	execConfig.OpenStdin = false
 	execConfig.OpenStdout = true
 	execConfig.OpenStderr = true

 	execConfig.ContainerID = cntr.ID

 	execConfig.DetachKeys = []byte{}
 	execConfig.Entrypoint = entrypoint
 	execConfig.Args = args
 	execConfig.Tty = false
 	execConfig.Privileged = false

 	execConfig.User = cntr.Config.User

 	execConfig.WorkingDir = cntr.Config.WorkingDir

 
 	linkedEnv, err := d.setupLinkedContainers(cntr)
 	if err != nil {
 		return nil, err
 	}
 	execConfig.Env = container.ReplaceOrAppendEnvValues(cntr.CreateDaemonEnvironment(execConfig.Tty, linkedEnv), execConfig.Env)

 	d.registerExecCommand(cntr, execConfig)

 	attributes := map[string]string{
 		"execID": execConfig.ID,
 	}
 	d.LogContainerEventWithAttributes(cntr, "exec_create: "+execConfig.Entrypoint+" "+strings.Join(execConfig.Args, " "), attributes)

 
 	output := &limitedBuffer{}

 	err = d.ContainerExecStart(ctx, execConfig.ID, nil, output, output)

 	if err != nil {
 		return nil, err
 	}
 	info, err := d.getExecConfig(execConfig.ID)
 	if err != nil {
 		return nil, err
 	}
 	if info.ExitCode == nil {

 		return nil, fmt.Errorf("healthcheck for container %s has no exit code", cntr.ID)

 	}
 	// Note: Go's json package will handle invalid UTF-8 for us
 	out := output.String()
 	return &types.HealthcheckResult{
 		End:      time.Now(),
 		ExitCode: *info.ExitCode,
 		Output:   out,
 	}, nil
 }
 
 // Update the container's Status.Health struct based on the latest probe's result.

 func handleProbeResult(d *Daemon, c *container.Container, result *types.HealthcheckResult, done chan struct{}) {

 	c.Lock()
 	defer c.Unlock()
 

 	// probe may have been cancelled while waiting on lock. Ignore result then
 	select {
 	case <-done:
 		return
 	default:
 	}
 

 	retries := c.Config.Healthcheck.Retries
 	if retries <= 0 {

 		retries = defaultProbeRetries

 	}
 
 	h := c.State.Health

 	oldStatus := h.Status()

 
 	if len(h.Log) >= maxLogEntries {
 		h.Log = append(h.Log[len(h.Log)+1-maxLogEntries:], result)
 	} else {
 		h.Log = append(h.Log, result)
 	}
 
 	if result.ExitCode == exitStatusHealthy {
 		h.FailingStreak = 0

 		h.SetStatus(types.Healthy)

 	} else { // Failure (including invalid exit code)
 		shouldIncrementStreak := true
 
 		// If the container is starting (i.e. we never had a successful health check)
 		// then we check if we are within the start period of the container in which
 		// case we do not increment the failure streak.

 		if h.Status() == types.Starting {

 			startPeriod := timeoutWithDefault(c.Config.Healthcheck.StartPeriod, defaultStartPeriod)
 			timeSinceStart := result.Start.Sub(c.State.StartedAt)
 
 			// If still within the start period, then don't increment failing streak.
 			if timeSinceStart < startPeriod {
 				shouldIncrementStreak = false
 			}
 		}
 
 		if shouldIncrementStreak {
 			h.FailingStreak++
 
 			if h.FailingStreak >= retries {

 				h.SetStatus(types.Unhealthy)

 			}

 		}
 		// Else we're starting or healthy. Stay in that state.
 	}
 

 	// replicate Health status changes

 	if err := c.CheckpointTo(d.containersReplica); err != nil {

 		// queries will be inconsistent until the next probe runs or other state mutations

 		// checkpoint the container

 		logrus.Errorf("Error replicating health state for container %s: %v", c.ID, err)
 	}
 

 	current := h.Status()
 	if oldStatus != current {
 		d.LogContainerEvent(c, "health_status: "+current)

 	}
 }
 
 // Run the container's monitoring thread until notified via "stop".
 // There is never more than one monitor thread running per container at a time.
 func monitor(d *Daemon, c *container.Container, stop chan struct{}, probe probe) {
 	probeTimeout := timeoutWithDefault(c.Config.Healthcheck.Timeout, defaultProbeTimeout)
 	probeInterval := timeoutWithDefault(c.Config.Healthcheck.Interval, defaultProbeInterval)
 	for {
 		select {
 		case <-stop:

 			logrus.Debugf("Stop healthcheck monitoring for container %s (received while idle)", c.ID)

 			return
 		case <-time.After(probeInterval):

 			logrus.Debugf("Running health check for container %s ...", c.ID)

 			startTime := time.Now()
 			ctx, cancelProbe := context.WithTimeout(context.Background(), probeTimeout)

 			results := make(chan *types.HealthcheckResult, 1)

 			go func() {

 				healthChecksCounter.Inc()

 				result, err := probe.run(ctx, d, c)
 				if err != nil {

 					healthChecksFailedCounter.Inc()

 					logrus.Warnf("Health check for container %s error: %v", c.ID, err)

 					results <- &types.HealthcheckResult{
 						ExitCode: -1,
 						Output:   err.Error(),
 						Start:    startTime,
 						End:      time.Now(),
 					}
 				} else {
 					result.Start = startTime

 					logrus.Debugf("Health check for container %s done (exitCode=%d)", c.ID, result.ExitCode)

 					results <- result
 				}
 				close(results)
 			}()
 			select {
 			case <-stop:

 				logrus.Debugf("Stop healthcheck monitoring for container %s (received while probing)", c.ID)

 				cancelProbe()

 				// Wait for probe to exit (it might take a while to respond to the TERM
 				// signal and we don't want dying probes to pile up).
 				<-results

 				return
 			case result := <-results:

 				handleProbeResult(d, c, result, stop)

 				// Stop timeout
 				cancelProbe()
 			case <-ctx.Done():

 				logrus.Debugf("Health check for container %s taking too long", c.ID)

 				handleProbeResult(d, c, &types.HealthcheckResult{
 					ExitCode: -1,
 					Output:   fmt.Sprintf("Health check exceeded timeout (%v)", probeTimeout),
 					Start:    startTime,
 					End:      time.Now(),

 				}, stop)

 				cancelProbe()
 				// Wait for probe to exit (it might take a while to respond to the TERM
 				// signal and we don't want dying probes to pile up).
 				<-results
 			}
 		}
 	}
 }
 
 // Get a suitable probe implementation for the container's healthcheck configuration.

 // Nil will be returned if no healthcheck was configured or NONE was set.

 func getProbe(c *container.Container) probe {
 	config := c.Config.Healthcheck
 	if config == nil || len(config.Test) == 0 {
 		return nil
 	}
 	switch config.Test[0] {
 	case "CMD":
 		return &cmdProbe{shell: false}
 	case "CMD-SHELL":
 		return &cmdProbe{shell: true}

 	case "NONE":
 		return nil

 	default:

 		logrus.Warnf("Unknown healthcheck type '%s' (expected 'CMD') in container %s", config.Test[0], c.ID)

 		return nil
 	}
 }
 
 // Ensure the health-check monitor is running or not, depending on the current
 // state of the container.
 // Called from monitor.go, with c locked.
 func (d *Daemon) updateHealthMonitor(c *container.Container) {
 	h := c.State.Health
 	if h == nil {
 		return // No healthcheck configured
 	}
 
 	probe := getProbe(c)
 	wantRunning := c.Running && !c.Paused && probe != nil
 	if wantRunning {
 		if stop := h.OpenMonitorChannel(); stop != nil {
 			go monitor(d, c, stop, probe)
 		}
 	} else {
 		h.CloseMonitorChannel()
 	}
 }
 
 // Reset the health state for a newly-started, restarted or restored container.
 // initHealthMonitor is called from monitor.go and we should never be running
 // two instances at once.
 // Called with c locked.
 func (d *Daemon) initHealthMonitor(c *container.Container) {

 	// If no healthcheck is setup then don't init the monitor
 	if getProbe(c) == nil {

 		return
 	}
 
 	// This is needed in case we're auto-restarting
 	d.stopHealthchecks(c)
 

 	if h := c.State.Health; h != nil {

 		h.SetStatus(types.Starting)

 		h.FailingStreak = 0
 	} else {

 		h := &container.Health{}

 		h.SetStatus(types.Starting)

 		c.State.Health = h
 	}
 
 	d.updateHealthMonitor(c)
 }
 
 // Called when the container is being stopped (whether because the health check is
 // failing or for any other reason).
 func (d *Daemon) stopHealthchecks(c *container.Container) {
 	h := c.State.Health
 	if h != nil {
 		h.CloseMonitorChannel()
 	}
 }
 
 // Buffer up to maxOutputLen bytes. Further data is discarded.
 type limitedBuffer struct {
 	buf       bytes.Buffer

 	mu        sync.Mutex

 	truncated bool // indicates that data has been lost
 }
 
 // Append to limitedBuffer while there is room.
 func (b *limitedBuffer) Write(data []byte) (int, error) {

 	b.mu.Lock()
 	defer b.mu.Unlock()
 

 	bufLen := b.buf.Len()
 	dataLen := len(data)
 	keep := min(maxOutputLen-bufLen, dataLen)
 	if keep > 0 {
 		b.buf.Write(data[:keep])
 	}
 	if keep < dataLen {
 		b.truncated = true
 	}
 	return dataLen, nil
 }
 
 // The contents of the buffer, with "..." appended if it overflowed.
 func (b *limitedBuffer) String() string {

 	b.mu.Lock()
 	defer b.mu.Unlock()
 

 	out := b.buf.String()
 	if b.truncated {
 		out = out + "..."
 	}
 	return out
 }
 
 // If configuredValue is zero, use defaultValue instead.
 func timeoutWithDefault(configuredValue time.Duration, defaultValue time.Duration) time.Duration {
 	if configuredValue == 0 {
 		return defaultValue
 	}
 	return configuredValue
 }
 
 func min(x, y int) int {
 	if x < y {
 		return x
 	}
 	return y
 }

 
 func getShell(config *containertypes.Config) []string {
 	if len(config.Shell) != 0 {
 		return config.Shell
 	}
 	if runtime.GOOS != "windows" {
 		return []string{"/bin/sh", "-c"}
 	}
 	return []string{"cmd", "/S", "/C"}
 }