package agent import ( "crypto/tls" "fmt" "io" "io/ioutil" "log" "net" "net/http" "os" "os/exec" "sync" "syscall" "time" "github.com/armon/circbuf" "github.com/hashicorp/consul/agent/consul/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. 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 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) c.Logger.Printf("[DEBUG] agent: pausing %v before first invocation of %s", initialPauseTime, c.Script) 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 cmd, err := ExecScript(c.Script) if err != nil { c.Logger.Printf("[ERR] agent: failed to setup invoke '%s': %s", c.Script, err) c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error()) return } // Collect the output output, _ := circbuf.NewBuffer(CheckBufSize) cmd.Stdout = output cmd.Stderr = output // Start the check if err := cmd.Start(); err != nil { c.Logger.Printf("[ERR] agent: failed to invoke '%s': %s", c.Script, err) c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error()) return } // Wait for the check to complete errCh := make(chan error, 2) go func() { errCh <- cmd.Wait() }() go func() { if c.Timeout > 0 { time.Sleep(c.Timeout) } else { time.Sleep(30 * time.Second) } errCh <- fmt.Errorf("Timed out running check '%s'", c.Script) }() err = <-errCh // Get the output, add a message about truncation 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, c.Script, outputStr) // Check if the check passed if err == nil { 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 { 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 c.Logger.Printf("[WARN] agent: Check '%v' is now critical", c.CheckID) c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, outputStr) } // 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 TTL time.Duration Logger *log.Logger timer *time.Timer lastOutput string lastOutputLock sync.RWMutex 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: c.Logger.Printf("[WARN] agent: Check '%v' missed TTL, is now critical", c.CheckID) c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, c.getExpiredOutput()) 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) } // 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) { c.Logger.Printf("[DEBUG] agent: Check '%v' status is now %v", 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() 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. // 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() // 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) } // Format the response body result := fmt.Sprintf("HTTP GET %s: %s Output: %s", c.HTTP, resp.Status, output.String()) 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)) } // 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 Script string DockerContainerID string Shell string Interval time.Duration Logger *log.Logger client *DockerClient stop chan struct{} } func (c *CheckDocker) Start() { if c.stop != nil { panic("Docker check already started") } if c.Logger == nil { c.Logger = log.New(ioutil.Discard, "", 0) } if c.Shell == "" { c.Shell = os.Getenv("SHELL") if c.Shell == "" { c.Shell = "/bin/sh" } } c.stop = make(chan struct{}) go c.run() } func (c *CheckDocker) Stop() { if c.stop == nil { panic("Stop called before start") } close(c.stop) } func (c *CheckDocker) run() { firstWait := lib.RandomStagger(c.Interval) c.Logger.Printf("[DEBUG] agent: pausing %v before first invocation of %s -c %s in container %s", firstWait, c.Shell, c.Script, c.DockerContainerID) next := time.After(firstWait) for { select { case <-next: c.check() next = time.After(c.Interval) case <-c.stop: return } } } func (c *CheckDocker) check() { var out string status, b, err := c.doCheck() 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) } 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) { 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 } }