package checks import ( "crypto/tls" "fmt" "io" "io/ioutil" "log" "net" "net/http" "os" osexec "os/exec" "sync" "syscall" "time" "github.com/armon/circbuf" "github.com/hashicorp/consul/agent/exec" "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 // BufSize is the maximum size of the captured // check output. Prevents an enormous buffer // from being captured BufSize = 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 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 *osexec.Cmd var err error if len(c.ScriptArgs) > 0 { cmd, err = exec.Subprocess(c.ScriptArgs) } else { cmd, err = exec.Script(c.Script) } if err != nil { c.Logger.Printf("[ERR] agent: Check %q failed to setup: %s", c.CheckID, err) c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error()) return } // Collect the output output, _ := circbuf.NewBuffer(BufSize) cmd.Stdout = output cmd.Stderr = output exec.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("[TRACE] agent: Check %q output: %s", c.CheckID, outputStr) return outputStr } // Start the check if err := cmd.Start(); err != nil { c.Logger.Printf("[ERR] agent: Check %q failed to invoke: %s", c.CheckID, 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 := exec.KillCommandSubtree(cmd); err != nil { c.Logger.Printf("[WARN] agent: Check %q failed to kill after timeout: %s", c.CheckID, err) } msg := fmt.Sprintf("Timed out (%s) running check", timeout.String()) c.Logger.Printf("[WARN] agent: Check %q: %s", c.CheckID, msg) outputStr := truncateAndLogOutput() if len(outputStr) > 0 { msg += "\n\n" + outputStr } 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 { c.Logger.Printf("[DEBUG] agent: Check %q 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.(*osexec.ExitError) if ok { if status, ok := exitErr.Sys().(syscall.WaitStatus); ok { code := status.ExitStatus() if code == 1 { c.Logger.Printf("[WARN] agent: Check %q 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 %q 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 %q 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 %q status is now %s", 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) } // 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 TLSClientConfig *tls.Config 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 // Take on the supplied TLS client config. trans.TLSClientConfig = c.TLSClientConfig // 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) 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: Check %q HTTP request failed: %s", c.CheckID, 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: Check %q HTTP request failed: %s", c.CheckID, 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(BufSize) if _, err := io.Copy(output, resp.Body); err != nil { c.Logger.Printf("[WARN] agent: Check %q error while reading body: %s", c.CheckID, err) } // Format the response body result := fmt.Sprintf("HTTP %s %s: %s Output: %s", method, c.HTTP, resp.Status, output.String()) if resp.StatusCode >= 200 && resp.StatusCode <= 299 { // PASSING (2xx) c.Logger.Printf("[DEBUG] agent: Check %q 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 %q is now warning", c.CheckID) c.Notify.UpdateCheck(c.CheckID, api.HealthWarning, result) } else { // CRITICAL c.Logger.Printf("[WARN] agent: Check %q 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) 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: Check %q socket connection failed: %s", c.CheckID, err) c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error()) return } conn.Close() c.Logger.Printf("[DEBUG] agent: Check %q 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 ScriptArgs []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() { defer c.Client.Close() firstWait := lib.RandomStagger(c.Interval) 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 %q: %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("[TRACE] agent: Check %q output: %s", c.CheckID, out) } if status == api.HealthCritical { c.Logger.Printf("[WARN] agent: Check %q 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] agent: Check %q failed with exit code: %d", c.CheckID, exitCode) return api.HealthWarning, buf, nil default: c.Logger.Printf("[DEBUG] agent: Check %q failed with exit code: %d", c.CheckID, exitCode) return api.HealthCritical, buf, nil } } // CheckGRPC is used to periodically send request to a gRPC server // application that implements gRPC health-checking protocol. // The check is passing if returned status is SERVING. // The check is critical if connection fails or returned status is // not SERVING. type CheckGRPC struct { Notify CheckNotifier CheckID types.CheckID GRPC string Interval time.Duration Timeout time.Duration TLSClientConfig *tls.Config Logger *log.Logger probe *GrpcHealthProbe stop bool stopCh chan struct{} stopLock sync.Mutex } func (c *CheckGRPC) Start() { c.stopLock.Lock() defer c.stopLock.Unlock() timeout := 10 * time.Second if c.Timeout > 0 { timeout = c.Timeout } c.probe = NewGrpcHealthProbe(c.GRPC, timeout, c.TLSClientConfig) c.stop = false c.stopCh = make(chan struct{}) go c.run() } func (c *CheckGRPC) 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 } } } func (c *CheckGRPC) check() { err := c.probe.Check() if err != nil { c.Logger.Printf("[DEBUG] agent: Check %q failed: %s", c.CheckID, err.Error()) c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error()) } else { c.Logger.Printf("[DEBUG] agent: Check %q is passing", c.CheckID) c.Notify.UpdateCheck(c.CheckID, api.HealthPassing, fmt.Sprintf("gRPC check %s: success", c.GRPC)) } } func (c *CheckGRPC) Stop() { c.stopLock.Lock() defer c.stopLock.Unlock() if !c.stop { c.stop = true close(c.stopCh) } }