open-consul/agent/check.go

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package agent
import (
"crypto/tls"
"fmt"
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"io"
"io/ioutil"
"log"
"net"
"net/http"
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"os"
"os/exec"
"sync"
"syscall"
"time"
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"github.com/armon/circbuf"
"github.com/hashicorp/consul/agent/structs"
"github.com/hashicorp/consul/api"
"github.com/hashicorp/consul/lib"
"github.com/hashicorp/consul/types"
"github.com/hashicorp/go-cleanhttp"
)
const (
// MinInterval is the minimal interval between
// two checks. Do not allow for a interval below this value.
// Otherwise we risk fork bombing a system.
MinInterval = time.Second
// CheckBufSize is the maximum size of the captured
// check output. Prevents an enormous buffer
// from being captured
CheckBufSize = 4 * 1024 // 4KB
// UserAgent is the value of the User-Agent header
// for HTTP health checks.
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UserAgent = "Consul Health Check"
)
// CheckNotifier interface is used by the CheckMonitor
// to notify when a check has a status update. The update
// should take care to be idempotent.
type CheckNotifier interface {
UpdateCheck(checkID types.CheckID, status, output string)
}
// CheckMonitor is used to periodically invoke a script to
// determine the health of a given check. It is compatible with
// nagios plugins and expects the output in the same format.
type CheckMonitor struct {
Notify CheckNotifier
CheckID types.CheckID
Script string
ScriptArgs []string
Interval time.Duration
Timeout time.Duration
Logger *log.Logger
stop bool
stopCh chan struct{}
stopLock sync.Mutex
}
// Start is used to start a check monitor.
// Monitor runs until stop is called
func (c *CheckMonitor) Start() {
c.stopLock.Lock()
defer c.stopLock.Unlock()
c.stop = false
c.stopCh = make(chan struct{})
go c.run()
}
// Stop is used to stop a check monitor.
func (c *CheckMonitor) Stop() {
c.stopLock.Lock()
defer c.stopLock.Unlock()
if !c.stop {
c.stop = true
close(c.stopCh)
}
}
// run is invoked by a goroutine to run until Stop() is called
func (c *CheckMonitor) run() {
// Get the randomized initial pause time
initialPauseTime := lib.RandomStagger(c.Interval)
next := time.After(initialPauseTime)
for {
select {
case <-next:
c.check()
next = time.After(c.Interval)
case <-c.stopCh:
return
}
}
}
// check is invoked periodically to perform the script check
func (c *CheckMonitor) check() {
// Create the command
var cmd *exec.Cmd
var err error
var cmdDisplay string
if len(c.ScriptArgs) > 0 {
cmdDisplay = fmt.Sprintf("%v", c.ScriptArgs)
cmd, err = ExecSubprocess(c.ScriptArgs)
} else {
cmdDisplay = c.Script
cmd, err = ExecScript(c.Script)
}
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if err != nil {
c.Logger.Printf("[ERR] agent: failed to setup invoke '%s': %s", cmdDisplay, err)
c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error())
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return
}
// Collect the output
output, _ := circbuf.NewBuffer(CheckBufSize)
cmd.Stdout = output
cmd.Stderr = output
SetSysProcAttr(cmd)
truncateAndLogOutput := func() string {
outputStr := string(output.Bytes())
if output.TotalWritten() > output.Size() {
outputStr = fmt.Sprintf("Captured %d of %d bytes\n...\n%s",
output.Size(), output.TotalWritten(), outputStr)
}
c.Logger.Printf("[DEBUG] agent: Check '%s' script '%s' output: %s",
c.CheckID, cmdDisplay, outputStr)
return outputStr
}
// Start the check
if err := cmd.Start(); err != nil {
c.Logger.Printf("[ERR] agent: failed to invoke '%s': %s", cmdDisplay, err)
c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error())
return
}
// Wait for the check to complete
waitCh := make(chan error, 1)
go func() {
waitCh <- cmd.Wait()
}()
timeout := 30 * time.Second
if c.Timeout > 0 {
timeout = c.Timeout
}
select {
case <-time.After(timeout):
if err := KillCommandSubtree(cmd); err != nil {
c.Logger.Printf("[WARN] Failed to kill check '%s' after timeout: %v", cmdDisplay, err)
}
msg := fmt.Sprintf("Timed out (%s) running check", timeout.String())
c.Logger.Printf("[WARN] %s '%s'", msg, cmdDisplay)
outputStr := truncateAndLogOutput()
if len(outputStr) > 0 {
msg += "\n\n" + outputStr
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}
c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, msg)
// Now wait for the process to exit so we never start another
// instance concurrently.
<-waitCh
return
case err = <-waitCh:
// The process returned before the timeout, proceed normally
}
// Check if the check passed
outputStr := truncateAndLogOutput()
if err == nil {
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c.Logger.Printf("[DEBUG] agent: Check '%v' is passing", c.CheckID)
c.Notify.UpdateCheck(c.CheckID, api.HealthPassing, outputStr)
return
}
// If the exit code is 1, set check as warning
exitErr, ok := err.(*exec.ExitError)
if ok {
if status, ok := exitErr.Sys().(syscall.WaitStatus); ok {
code := status.ExitStatus()
if code == 1 {
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c.Logger.Printf("[WARN] agent: Check '%v' is now warning", c.CheckID)
c.Notify.UpdateCheck(c.CheckID, api.HealthWarning, outputStr)
return
}
}
}
// Set the health as critical
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c.Logger.Printf("[WARN] agent: Check '%v' is now critical", c.CheckID)
c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, outputStr)
}
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// CheckTTL is used to apply a TTL to check status,
// and enables clients to set the status of a check
// but upon the TTL expiring, the check status is
// automatically set to critical.
type CheckTTL struct {
Notify CheckNotifier
CheckID types.CheckID
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TTL time.Duration
Logger *log.Logger
timer *time.Timer
lastOutput string
lastOutputLock sync.RWMutex
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stop bool
stopCh chan struct{}
stopLock sync.Mutex
}
// Start is used to start a check ttl, runs until Stop()
func (c *CheckTTL) Start() {
c.stopLock.Lock()
defer c.stopLock.Unlock()
c.stop = false
c.stopCh = make(chan struct{})
c.timer = time.NewTimer(c.TTL)
go c.run()
}
// Stop is used to stop a check ttl.
func (c *CheckTTL) Stop() {
c.stopLock.Lock()
defer c.stopLock.Unlock()
if !c.stop {
c.timer.Stop()
c.stop = true
close(c.stopCh)
}
}
// run is used to handle TTL expiration and to update the check status
func (c *CheckTTL) run() {
for {
select {
case <-c.timer.C:
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c.Logger.Printf("[WARN] agent: Check '%v' missed TTL, is now critical",
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c.CheckID)
c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, c.getExpiredOutput())
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case <-c.stopCh:
return
}
}
}
// getExpiredOutput formats the output for the case when the TTL is expired.
func (c *CheckTTL) getExpiredOutput() string {
c.lastOutputLock.RLock()
defer c.lastOutputLock.RUnlock()
const prefix = "TTL expired"
if c.lastOutput == "" {
return prefix
}
return fmt.Sprintf("%s (last output before timeout follows): %s", prefix, c.lastOutput)
}
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// SetStatus is used to update the status of the check,
// and to renew the TTL. If expired, TTL is restarted.
func (c *CheckTTL) SetStatus(status, output string) {
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c.Logger.Printf("[DEBUG] agent: Check '%v' status is now %v",
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c.CheckID, status)
c.Notify.UpdateCheck(c.CheckID, status, output)
// Store the last output so we can retain it if the TTL expires.
c.lastOutputLock.Lock()
c.lastOutput = output
c.lastOutputLock.Unlock()
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c.timer.Reset(c.TTL)
}
// persistedCheck is used to serialize a check and write it to disk
// so that it may be restored later on.
type persistedCheck struct {
Check *structs.HealthCheck
ChkType *structs.CheckType
Token string
}
// persistedCheckState is used to persist the current state of a given
// check. This is different from the check definition, and includes an
// expiration timestamp which is used to determine staleness on later
// agent restarts.
type persistedCheckState struct {
CheckID types.CheckID
Output string
Status string
Expires int64
}
// CheckHTTP is used to periodically make an HTTP request to
// determine the health of a given check.
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// The check is passing if the response code is 2XX.
// The check is warning if the response code is 429.
// The check is critical if the response code is anything else
// or if the request returns an error
type CheckHTTP struct {
Notify CheckNotifier
CheckID types.CheckID
HTTP string
Header map[string][]string
Method string
Interval time.Duration
Timeout time.Duration
Logger *log.Logger
TLSSkipVerify bool
httpClient *http.Client
stop bool
stopCh chan struct{}
stopLock sync.Mutex
}
// Start is used to start an HTTP check.
// The check runs until stop is called
func (c *CheckHTTP) Start() {
c.stopLock.Lock()
defer c.stopLock.Unlock()
if c.httpClient == nil {
// Create the transport. We disable HTTP Keep-Alive's to prevent
// failing checks due to the keepalive interval.
trans := cleanhttp.DefaultTransport()
trans.DisableKeepAlives = true
// Skip SSL certificate verification if TLSSkipVerify is true
if trans.TLSClientConfig == nil {
trans.TLSClientConfig = &tls.Config{
InsecureSkipVerify: c.TLSSkipVerify,
}
} else {
trans.TLSClientConfig.InsecureSkipVerify = c.TLSSkipVerify
}
// Create the HTTP client.
c.httpClient = &http.Client{
Timeout: 10 * time.Second,
Transport: trans,
}
// For long (>10s) interval checks the http timeout is 10s, otherwise the
// timeout is the interval. This means that a check *should* return
// before the next check begins.
if c.Timeout > 0 && c.Timeout < c.Interval {
c.httpClient.Timeout = c.Timeout
} else if c.Interval < 10*time.Second {
c.httpClient.Timeout = c.Interval
}
}
c.stop = false
c.stopCh = make(chan struct{})
go c.run()
}
// Stop is used to stop an HTTP check.
func (c *CheckHTTP) Stop() {
c.stopLock.Lock()
defer c.stopLock.Unlock()
if !c.stop {
c.stop = true
close(c.stopCh)
}
}
// run is invoked by a goroutine to run until Stop() is called
func (c *CheckHTTP) run() {
// Get the randomized initial pause time
initialPauseTime := lib.RandomStagger(c.Interval)
c.Logger.Printf("[DEBUG] agent: pausing %v before first HTTP request of %s", initialPauseTime, c.HTTP)
next := time.After(initialPauseTime)
for {
select {
case <-next:
c.check()
next = time.After(c.Interval)
case <-c.stopCh:
return
}
}
}
// check is invoked periodically to perform the HTTP check
func (c *CheckHTTP) check() {
method := c.Method
if method == "" {
method = "GET"
}
req, err := http.NewRequest(method, c.HTTP, nil)
if err != nil {
c.Logger.Printf("[WARN] agent: http request failed '%s': %s", c.HTTP, err)
c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error())
return
}
req.Header = http.Header(c.Header)
// this happens during testing but not in prod
if req.Header == nil {
req.Header = make(http.Header)
}
if host := req.Header.Get("Host"); host != "" {
req.Host = host
}
if req.Header.Get("User-Agent") == "" {
req.Header.Set("User-Agent", UserAgent)
}
if req.Header.Get("Accept") == "" {
req.Header.Set("Accept", "text/plain, text/*, */*")
}
resp, err := c.httpClient.Do(req)
if err != nil {
c.Logger.Printf("[WARN] agent: http request failed '%s': %s", c.HTTP, err)
c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error())
return
}
defer resp.Body.Close()
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// Read the response into a circular buffer to limit the size
output, _ := circbuf.NewBuffer(CheckBufSize)
if _, err := io.Copy(output, resp.Body); err != nil {
c.Logger.Printf("[WARN] agent: Check '%v': Get error while reading body: %s", c.CheckID, err)
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}
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// Format the response body
result := fmt.Sprintf("HTTP GET %s: %s Output: %s", c.HTTP, resp.Status, output.String())
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if resp.StatusCode >= 200 && resp.StatusCode <= 299 {
// PASSING (2xx)
c.Logger.Printf("[DEBUG] agent: Check '%v' is passing", c.CheckID)
c.Notify.UpdateCheck(c.CheckID, api.HealthPassing, result)
} else if resp.StatusCode == 429 {
// WARNING
// 429 Too Many Requests (RFC 6585)
// The user has sent too many requests in a given amount of time.
c.Logger.Printf("[WARN] agent: Check '%v' is now warning", c.CheckID)
c.Notify.UpdateCheck(c.CheckID, api.HealthWarning, result)
} else {
// CRITICAL
c.Logger.Printf("[WARN] agent: Check '%v' is now critical", c.CheckID)
c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, result)
}
}
// CheckTCP is used to periodically make an TCP/UDP connection to
// determine the health of a given check.
// The check is passing if the connection succeeds
// The check is critical if the connection returns an error
type CheckTCP struct {
Notify CheckNotifier
CheckID types.CheckID
TCP string
Interval time.Duration
Timeout time.Duration
Logger *log.Logger
dialer *net.Dialer
stop bool
stopCh chan struct{}
stopLock sync.Mutex
}
// Start is used to start a TCP check.
// The check runs until stop is called
func (c *CheckTCP) Start() {
c.stopLock.Lock()
defer c.stopLock.Unlock()
if c.dialer == nil {
// Create the socket dialer
c.dialer = &net.Dialer{DualStack: true}
// For long (>10s) interval checks the socket timeout is 10s, otherwise
// the timeout is the interval. This means that a check *should* return
// before the next check begins.
if c.Timeout > 0 && c.Timeout < c.Interval {
c.dialer.Timeout = c.Timeout
} else if c.Interval < 10*time.Second {
c.dialer.Timeout = c.Interval
}
}
c.stop = false
c.stopCh = make(chan struct{})
go c.run()
}
// Stop is used to stop a TCP check.
func (c *CheckTCP) Stop() {
c.stopLock.Lock()
defer c.stopLock.Unlock()
if !c.stop {
c.stop = true
close(c.stopCh)
}
}
// run is invoked by a goroutine to run until Stop() is called
func (c *CheckTCP) run() {
// Get the randomized initial pause time
initialPauseTime := lib.RandomStagger(c.Interval)
c.Logger.Printf("[DEBUG] agent: pausing %v before first socket connection of %s", initialPauseTime, c.TCP)
next := time.After(initialPauseTime)
for {
select {
case <-next:
c.check()
next = time.After(c.Interval)
case <-c.stopCh:
return
}
}
}
// check is invoked periodically to perform the TCP check
func (c *CheckTCP) check() {
conn, err := c.dialer.Dial(`tcp`, c.TCP)
if err != nil {
c.Logger.Printf("[WARN] agent: socket connection failed '%s': %s", c.TCP, err)
c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error())
return
}
conn.Close()
c.Logger.Printf("[DEBUG] agent: Check '%v' is passing", c.CheckID)
c.Notify.UpdateCheck(c.CheckID, api.HealthPassing, fmt.Sprintf("TCP connect %s: Success", c.TCP))
}
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// CheckDocker is used to periodically invoke a script to
// determine the health of an application running inside a
// Docker Container. We assume that the script is compatible
// with nagios plugins and expects the output in the same format.
type CheckDocker struct {
Notify CheckNotifier
CheckID types.CheckID
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Script string
ScriptArgs []string
DockerContainerID string
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Shell string
Interval time.Duration
Logger *log.Logger
client *DockerClient
stop chan struct{}
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}
func (c *CheckDocker) Start() {
if c.stop != nil {
panic("Docker check already started")
}
if c.Logger == nil {
c.Logger = log.New(ioutil.Discard, "", 0)
}
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if c.Shell == "" {
c.Shell = os.Getenv("SHELL")
if c.Shell == "" {
c.Shell = "/bin/sh"
}
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}
c.stop = make(chan struct{})
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go c.run()
}
func (c *CheckDocker) Stop() {
if c.stop == nil {
panic("Stop called before start")
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}
close(c.stop)
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}
func (c *CheckDocker) run() {
firstWait := lib.RandomStagger(c.Interval)
next := time.After(firstWait)
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for {
select {
case <-next:
c.check()
next = time.After(c.Interval)
case <-c.stop:
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return
}
}
}
func (c *CheckDocker) check() {
var out string
status, b, err := c.doCheck()
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if err != nil {
c.Logger.Printf("[DEBUG] agent: Check '%s': %s", c.CheckID, err)
out = err.Error()
} else {
// out is already limited to CheckBufSize since we're getting a
// limited buffer. So we don't need to truncate it just report
// that it was truncated.
out = string(b.Bytes())
if int(b.TotalWritten()) > len(out) {
out = fmt.Sprintf("Captured %d of %d bytes\n...\n%s", len(out), b.TotalWritten(), out)
}
c.Logger.Printf("[DEBUG] agent: Check '%s' script '%s' output: %s", c.CheckID, c.Script, out)
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}
if status == api.HealthCritical {
c.Logger.Printf("[WARN] agent: Check '%v' is now critical", c.CheckID)
}
c.Notify.UpdateCheck(c.CheckID, status, out)
}
func (c *CheckDocker) doCheck() (string, *circbuf.Buffer, error) {
var cmd []string
if len(c.ScriptArgs) > 0 {
cmd = c.ScriptArgs
} else {
cmd = []string{c.Shell, "-c", c.Script}
}
execID, err := c.client.CreateExec(c.DockerContainerID, cmd)
if err != nil {
return api.HealthCritical, nil, err
}
buf, err := c.client.StartExec(c.DockerContainerID, execID)
if err != nil {
return api.HealthCritical, nil, err
}
exitCode, err := c.client.InspectExec(c.DockerContainerID, execID)
if err != nil {
return api.HealthCritical, nil, err
}
switch exitCode {
case 0:
return api.HealthPassing, buf, nil
case 1:
c.Logger.Printf("[DEBUG] Check failed with exit code: %d", exitCode)
return api.HealthWarning, buf, nil
default:
c.Logger.Printf("[DEBUG] Check failed with exit code: %d", exitCode)
return api.HealthCritical, buf, nil
}
}