Implemented Docker health checks

command/agent/agent.go

@@ -82,6 +82,9 @@ type Agent struct {
 	// checkTTLs maps the check ID to an associated check TTL
 	checkTTLs map[string]*CheckTTL
 
+	// checkDockers maps the check ID to an associated Docker Exec based check
+	checkDockers map[string]*CheckDocker
+
 	// checkLock protects updates to the check* maps
 	checkLock sync.Mutex
 
@@ -150,6 +153,7 @@ func Create(config *Config, logOutput io.Writer) (*Agent, error) {
 		checkTTLs:     make(map[string]*CheckTTL),
 		checkHTTPs:    make(map[string]*CheckHTTP),
 		checkTCPs:     make(map[string]*CheckTCP),
+		checkDockers:  make(map[string]*CheckDocker),
 		eventCh:       make(chan serf.UserEvent, 1024),
 		eventBuf:      make([]*UserEvent, 256),
 		shutdownCh:    make(chan struct{}),
@@ -831,7 +835,7 @@ func (a *Agent) AddCheck(check *structs.HealthCheck, chkType *CheckType, persist
 			tcp.Start()
 			a.checkTCPs[check.CheckID] = tcp
 
-		} else {
+		} else if chkType.IsMonitor() {
 			if existing, ok := a.checkMonitors[check.CheckID]; ok {
 				existing.Stop()
 			}
@@ -850,6 +854,27 @@ func (a *Agent) AddCheck(check *structs.HealthCheck, chkType *CheckType, persist
 			}
 			monitor.Start()
 			a.checkMonitors[check.CheckID] = monitor
+		} else if chkType.IsDocker() {
+			if existing, ok := a.checkDockers[check.CheckID]; ok {
+				existing.Stop()
+			}
+			if chkType.Interval < MinInterval {
+				a.logger.Println(fmt.Sprintf("[WARN] agent: check '%s' has interval below minimum of %v",
+					check.CheckID, MinInterval))
+				chkType.Interval = MinInterval
+			}
+
+			dockerCheck := &CheckDocker{
+				Notify:            &a.state,
+				CheckID:           check.CheckID,
+				DockerContainerId: chkType.DockerContainerId,
+				Shell:             chkType.Shell,
+				Script:            chkType.Script,
+				Interval:          chkType.Interval,
+				Logger:            a.logger,
+			}
+			dockerCheck.Start()
+			a.checkDockers[check.CheckID] = dockerCheck
 		}
 	}
 

command/agent/check.go

@@ -6,14 +6,16 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"os"
 	"os/exec"
 	"sync"
 	"syscall"
 	"time"
 
 	"github.com/armon/circbuf"
-	"github.com/hashicorp/go-cleanhttp"
+	docker "github.com/fsouza/go-dockerclient"
 	"github.com/hashicorp/consul/consul/structs"
+	"github.com/hashicorp/go-cleanhttp"
 )
 
 const (
@@ -42,6 +44,8 @@ type CheckType struct {
 	HTTP              string
 	TCP               string
 	Interval          time.Duration
+	DockerContainerId string
+	Shell             string
 
 	Timeout time.Duration
 	TTL     time.Duration
@@ -54,7 +58,7 @@ type CheckTypes []*CheckType
 
 // Valid checks if the CheckType is valid
 func (c *CheckType) Valid() bool {
-	return c.IsTTL() || c.IsMonitor() || c.IsHTTP() || c.IsTCP()
+	return c.IsTTL() || c.IsMonitor() || c.IsHTTP() || c.IsTCP() || c.IsDocker()
 }
 
 // IsTTL checks if this is a TTL type
@@ -64,7 +68,7 @@ func (c *CheckType) IsTTL() bool {
 
 // IsMonitor checks if this is a Monitor type
 func (c *CheckType) IsMonitor() bool {
-	return c.Script != "" && c.Interval != 0
+	return c.Script != "" && c.DockerContainerId == "" && c.Interval != 0
 }
 
 // IsHTTP checks if this is a HTTP type
@@ -77,6 +81,10 @@ func (c *CheckType) IsTCP() bool {
 	return c.TCP != "" && c.Interval != 0
 }
 
+func (c *CheckType) IsDocker() bool {
+	return c.DockerContainerId != "" && c.Shell != "" && c.Interval != 0
+}
+
 // CheckNotifier interface is used by the CheckMonitor
 // to notify when a check has a status update. The update
 // should take care to be idempotent.
@@ -493,3 +501,103 @@ func (c *CheckTCP) check() {
 	c.Logger.Printf("[DEBUG] agent: check '%v' is passing", c.CheckID)
 	c.Notify.UpdateCheck(c.CheckID, structs.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           string
+	Script            string
+	DockerContainerId string
+	Shell             string
+	Interval          time.Duration
+	Logger            *log.Logger
+
+	dockerClient  *docker.Client
+	exec          *docker.Exec
+	startExecOpts docker.StartExecOptions
+	stop          bool
+	stopCh        chan struct{}
+	stopLock      sync.Mutex
+}
+
+// Start is used to start checks.
+// Docker Checks runs until stop is called
+func (c *CheckDocker) Start() {
+	c.stopLock.Lock()
+	defer c.stopLock.Unlock()
+
+	//figure out the shell
+	if c.Shell == "" {
+		if otherShell := os.Getenv("SHELL"); otherShell != "" {
+			c.Shell = otherShell
+		} else {
+			c.Shell = "/bin/sh"
+		}
+	}
+
+	cmd := []string{c.Shell, "-c", c.Script}
+
+	//Set up the Exec since
+	execOpts := docker.CreateExecOptions{
+		AttachStdin:  false,
+		AttachStdout: true,
+		AttachStderr: true,
+		Tty:          false,
+		Cmd:          cmd,
+		Container:    c.DockerContainerId,
+	}
+	if exec, err := c.dockerClient.CreateExec(execOpts); err != nil {
+		c.exec = exec
+	} else {
+		c.Logger.Printf("[DEBUG] agent: Error while creating Exec: %s", err.Error())
+	}
+
+	c.startExecOpts = docker.StartExecOptions{
+		Detach: false,
+		Tty:    false,
+	}
+
+	c.stop = false
+	c.stopCh = make(chan struct{})
+	go c.run()
+}
+
+// Stop is used to stop a docker check.
+func (c *CheckDocker) 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 *CheckDocker) run() {
+	// Get the randomized initial pause time
+	initialPauseTime := randomStagger(c.Interval)
+	c.Logger.Printf("[DEBUG] agent: pausing %v before first invocation of %s -c %s in container %s", initialPauseTime, c.Shell, c.Script, c.DockerContainerId)
+	next := time.After(initialPauseTime)
+	for {
+		select {
+		case <-next:
+			c.check()
+			next = time.After(c.Interval)
+		case <-c.stopCh:
+			return
+		}
+	}
+}
+
+func (c *CheckDocker) check() {
+	err := c.dockerClient.StartExec(c.exec.ID, c.startExecOpts)
+	if err != nil {
+		c.Logger.Printf("[DEBUG] Error in executing health checks: %s", err.Error())
+		c.Notify.UpdateCheck(c.CheckID, structs.HealthCritical, err.Error())
+		return
+	}
+	c.Notify.UpdateCheck(c.CheckID, structs.HealthPassing, fmt.Sprintf("Script execution %s: Success", c.Script))
+}

command/agent/config.go

@@ -749,6 +749,9 @@ func FixupCheckType(raw interface{}) error {
 		case "service_id":
 			rawMap["serviceid"] = v
 			delete(rawMap, "service_id")
+		case "docker_container_id":
+			rawMap["DockerContainerId"] = v
+			delete(rawMap, "docker_container_id")
 		}
 	}
 

command/agent/config_test.go

@@ -1061,7 +1061,7 @@ func TestDecodeConfig_Service(t *testing.T) {
 
 func TestDecodeConfig_Check(t *testing.T) {
 	// Basics
-	input := `{"check": {"id": "chk1", "name": "mem", "notes": "foobar", "script": "/bin/check_redis", "interval": "10s", "ttl": "15s" }}`
+	input := `{"check": {"id": "chk1", "name": "mem", "notes": "foobar", "script": "/bin/check_redis", "interval": "10s", "ttl": "15s", "shell": "/bin/bash", "docker_container_id": "redis" }}`
 	config, err := DecodeConfig(bytes.NewReader([]byte(input)))
 	if err != nil {
 		t.Fatalf("err: %s", err)
@@ -1095,6 +1095,14 @@ func TestDecodeConfig_Check(t *testing.T) {
 	if chk.TTL != 15*time.Second {
 		t.Fatalf("bad: %v", chk)
 	}
+
+	if chk.Shell != "/bin/bash" {
+		t.Fatalf("bad: %v", chk)
+	}
+
+	if chk.DockerContainerId != "redis" {
+		t.Fatalf("bad: %v", chk)
+	}
 }
 
 func TestMergeConfig(t *testing.T) {