Move Healthcheck to middleware/pkg/healthcheck (#854)

* Move healthcheck out

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Move healthcheck to middleware/pkg/healthcheck

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

middleware/pkg/healthcheck/healthcheck.go

@@ -0,0 +1,236 @@
+package healthcheck
+
+import (
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"net/http"
+	"net/url"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+// UpstreamHostDownFunc can be used to customize how Down behaves.
+type UpstreamHostDownFunc func(*UpstreamHost) bool
+
+// UpstreamHost represents a single proxy upstream
+type UpstreamHost struct {
+	Conns             int64  // must be first field to be 64-bit aligned on 32-bit systems
+	Name              string // IP address (and port) of this upstream host
+	Fails             int32
+	FailTimeout       time.Duration
+	OkUntil           time.Time
+	CheckDown         UpstreamHostDownFunc
+	CheckURL          string
+	WithoutPathPrefix string
+	Checking          bool
+	CheckMu           sync.Mutex
+}
+
+// Down checks whether the upstream host is down or not.
+// Down will try to use uh.CheckDown first, and will fall
+// back to some default criteria if necessary.
+func (uh *UpstreamHost) Down() bool {
+	if uh.CheckDown == nil {
+		// Default settings
+		fails := atomic.LoadInt32(&uh.Fails)
+		after := false
+
+		uh.CheckMu.Lock()
+		until := uh.OkUntil
+		uh.CheckMu.Unlock()
+
+		if !until.IsZero() && time.Now().After(until) {
+			after = true
+		}
+
+		return after || fails > 0
+	}
+	return uh.CheckDown(uh)
+}
+
+// HostPool is a collection of UpstreamHosts.
+type HostPool []*UpstreamHost
+
+type HealthCheck struct {
+	wg          sync.WaitGroup // Used to wait for running goroutines to stop.
+	stop        chan struct{}  // Signals running goroutines to stop.
+	Hosts       HostPool
+	Policy      Policy
+	Spray       Policy
+	FailTimeout time.Duration
+	MaxFails    int32
+	Future      time.Duration
+	Path        string
+	Port        string
+	Interval    time.Duration
+}
+
+func (u *HealthCheck) Start() {
+	u.stop = make(chan struct{})
+	if u.Path != "" {
+		u.wg.Add(1)
+		go func() {
+			defer u.wg.Done()
+			u.HealthCheckWorker(u.stop)
+		}()
+	}
+}
+
+// Stop sends a signal to all goroutines started by this staticUpstream to exit
+// and waits for them to finish before returning.
+func (u *HealthCheck) Stop() error {
+	close(u.stop)
+	u.wg.Wait()
+	return nil
+}
+
+// This was moved into a thread so that each host could throw a health
+// check at the same time.  The reason for this is that if we are checking
+// 3 hosts, and the first one is gone, and we spend minutes timing out to
+// fail it, we would not have been doing any other health checks in that
+// time.  So we now have a per-host lock and a threaded health check.
+//
+// We use the Checking bool to avoid concurrent checks against the same
+// host; if one is taking a long time, the next one will find a check in
+// progress and simply return before trying.
+//
+// We are carefully avoiding having the mutex locked while we check,
+// otherwise checks will back up, potentially a lot of them if a host is
+// absent for a long time.  This arrangement makes checks quickly see if
+// they are the only one running and abort otherwise.
+func healthCheckURL(nextTs time.Time, host *UpstreamHost) {
+
+	// lock for our bool check.  We don't just defer the unlock because
+	// we don't want the lock held while http.Get runs
+	host.CheckMu.Lock()
+
+	// are we mid check?  Don't run another one
+	if host.Checking {
+		host.CheckMu.Unlock()
+		return
+	}
+
+	host.Checking = true
+	host.CheckMu.Unlock()
+
+	//log.Printf("[DEBUG] Healthchecking %s, nextTs is %s\n", url, nextTs.Local())
+
+	// fetch that url.  This has been moved into a go func because
+	// when the remote host is not merely not serving, but actually
+	// absent, then tcp syn timeouts can be very long, and so one
+	// fetch could last several check intervals
+	if r, err := http.Get(host.CheckURL); err == nil {
+		io.Copy(ioutil.Discard, r.Body)
+		r.Body.Close()
+
+		if r.StatusCode < 200 || r.StatusCode >= 400 {
+			log.Printf("[WARNING] Host %s health check returned HTTP code %d\n",
+				host.Name, r.StatusCode)
+			nextTs = time.Unix(0, 0)
+		}
+	} else {
+		log.Printf("[WARNING] Host %s health check probe failed: %v\n", host.Name, err)
+		nextTs = time.Unix(0, 0)
+	}
+
+	host.CheckMu.Lock()
+	host.Checking = false
+	host.OkUntil = nextTs
+	host.CheckMu.Unlock()
+}
+
+func (u *HealthCheck) healthCheck() {
+	for _, host := range u.Hosts {
+
+		if host.CheckURL == "" {
+			var hostName, checkPort string
+
+			// The DNS server might be an HTTP server.  If so, extract its name.
+			ret, err := url.Parse(host.Name)
+			if err == nil && len(ret.Host) > 0 {
+				hostName = ret.Host
+			} else {
+				hostName = host.Name
+			}
+
+			// Extract the port number from the parsed server name.
+			checkHostName, checkPort, err := net.SplitHostPort(hostName)
+			if err != nil {
+				checkHostName = hostName
+			}
+
+			if u.Port != "" {
+				checkPort = u.Port
+			}
+
+			host.CheckURL = "http://" + net.JoinHostPort(checkHostName, checkPort) + u.Path
+		}
+
+		// calculate this before the get
+		nextTs := time.Now().Add(u.Future)
+
+		// locks/bools should prevent requests backing up
+		go healthCheckURL(nextTs, host)
+	}
+}
+
+func (u *HealthCheck) HealthCheckWorker(stop chan struct{}) {
+	ticker := time.NewTicker(u.Interval)
+	u.healthCheck()
+	for {
+		select {
+		case <-ticker.C:
+			u.healthCheck()
+		case <-stop:
+			ticker.Stop()
+			return
+		}
+	}
+}
+
+func (u *HealthCheck) Select() *UpstreamHost {
+	pool := u.Hosts
+	if len(pool) == 1 {
+		if pool[0].Down() && u.Spray == nil {
+			return nil
+		}
+		return pool[0]
+	}
+	allDown := true
+	for _, host := range pool {
+		if !host.Down() {
+			allDown = false
+			break
+		}
+	}
+	if allDown {
+		if u.Spray == nil {
+			return nil
+		}
+		return u.Spray.Select(pool)
+	}
+
+	if u.Policy == nil {
+		h := (&Random{}).Select(pool)
+		if h != nil {
+			return h
+		}
+		if h == nil && u.Spray == nil {
+			return nil
+		}
+		return u.Spray.Select(pool)
+	}
+
+	h := u.Policy.Select(pool)
+	if h != nil {
+		return h
+	}
+
+	if u.Spray == nil {
+		return nil
+	}
+	return u.Spray.Select(pool)
+}

middleware/pkg/healthcheck/policy.go

@@ -1,4 +1,4 @@
-package proxy
+package healthcheck
 
 import (
 	"log"
@@ -6,8 +6,14 @@ import (
 	"sync/atomic"
 )
 
-// HostPool is a collection of UpstreamHosts.
+var (
-type HostPool []*UpstreamHost
+	SupportedPolicies = make(map[string]func() Policy)
+)
+
+// RegisterPolicy adds a custom policy to the proxy.
+func RegisterPolicy(name string, policy func() Policy) {
+	SupportedPolicies[name] = policy
+}
 
 // Policy decides how a host will be selected from a pool. When all hosts are unhealthy, it is assumed the
 // healthchecking failed. In this case each policy will *randomly* return a host from the pool to prevent

middleware/pkg/healthcheck/policy_test.go

@@ -1,6 +1,8 @@
-package proxy
+package healthcheck
 
 import (
+	"io/ioutil"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -41,6 +43,57 @@ func testPool() HostPool {
 	return HostPool(pool)
 }
 
+func TestRegisterPolicy(t *testing.T) {
+	name := "custom"
+	customPolicy := &customPolicy{}
+	RegisterPolicy(name, func() Policy { return customPolicy })
+	if _, ok := SupportedPolicies[name]; !ok {
+		t.Error("Expected supportedPolicies to have a custom policy.")
+	}
+
+}
+
+func TestHealthCheck(t *testing.T) {
+	log.SetOutput(ioutil.Discard)
+
+	u := &HealthCheck{
+		Hosts:       testPool(),
+		FailTimeout: 10 * time.Second,
+		Future:      60 * time.Second,
+		MaxFails:    1,
+	}
+
+	u.healthCheck()
+	// sleep a bit, it's async now
+	time.Sleep(time.Duration(2 * time.Second))
+
+	if u.Hosts[0].Down() {
+		t.Error("Expected first host in testpool to not fail healthcheck.")
+	}
+	if !u.Hosts[1].Down() {
+		t.Error("Expected second host in testpool to fail healthcheck.")
+	}
+}
+
+func TestSelect(t *testing.T) {
+	u := &HealthCheck{
+		Hosts:       testPool()[:3],
+		FailTimeout: 10 * time.Second,
+		Future:      60 * time.Second,
+		MaxFails:    1,
+	}
+	u.Hosts[0].OkUntil = time.Unix(0, 0)
+	u.Hosts[1].OkUntil = time.Unix(0, 0)
+	u.Hosts[2].OkUntil = time.Unix(0, 0)
+	if h := u.Select(); h != nil {
+		t.Error("Expected select to return nil as all host are down")
+	}
+	u.Hosts[2].OkUntil = time.Time{}
+	if h := u.Select(); h == nil {
+		t.Error("Expected select to not return nil")
+	}
+}
+
 func TestRoundRobinPolicy(t *testing.T) {
 	pool := testPool()
 	rrPolicy := &RoundRobin{}

middleware/proxy/google.go

@@ -14,6 +14,7 @@ import (
 	"time"
 
 	"github.com/coredns/coredns/middleware/pkg/debug"
+	"github.com/coredns/coredns/middleware/pkg/healthcheck"
 	"github.com/coredns/coredns/request"
 
 	"github.com/miekg/dns"
@@ -201,33 +202,32 @@ func extractAnswer(m *dns.Msg) ([]string, error) {
 func newUpstream(hosts []string, old *staticUpstream) Upstream {
 	upstream := &staticUpstream{
 		from: old.from,
-		Hosts:             nil,
+		HealthCheck: healthcheck.HealthCheck{
-		Policy:            &Random{},
-		Spray:             nil,
 			FailTimeout: 10 * time.Second,
 			MaxFails:    3,
 			Future:      60 * time.Second,
+		},
 		ex:                old.ex,
 		WithoutPathPrefix: old.WithoutPathPrefix,
 		IgnoredSubDomains: old.IgnoredSubDomains,
 	}
 
-	upstream.Hosts = make([]*UpstreamHost, len(hosts))
+	upstream.Hosts = make([]*healthcheck.UpstreamHost, len(hosts))
 	for i, h := range hosts {
-		uh := &UpstreamHost{
+		uh := &healthcheck.UpstreamHost{
 			Name:        h,
 			Conns:       0,
 			Fails:       0,
 			FailTimeout: upstream.FailTimeout,
 
-			CheckDown: func(upstream *staticUpstream) UpstreamHostDownFunc {
+			CheckDown: func(upstream *staticUpstream) healthcheck.UpstreamHostDownFunc {
-				return func(uh *UpstreamHost) bool {
+				return func(uh *healthcheck.UpstreamHost) bool {
 
 					down := false
 
-					uh.checkMu.Lock()
+					uh.CheckMu.Lock()
 					until := uh.OkUntil
-					uh.checkMu.Unlock()
+					uh.CheckMu.Unlock()
 
 					if !until.IsZero() && time.Now().After(until) {
 						down = true

middleware/proxy/grpc_test.go

@@ -4,11 +4,13 @@ import (
 	"testing"
 	"time"
 
+	"github.com/coredns/coredns/middleware/pkg/healthcheck"
+
 	"google.golang.org/grpc/grpclog"
 )
 
-func pool() []*UpstreamHost {
+func pool() []*healthcheck.UpstreamHost {
-	return []*UpstreamHost{
+	return []*healthcheck.UpstreamHost{
 		{
 			Name: "localhost:10053",
 		},
@@ -23,12 +25,12 @@ func TestStartupShutdown(t *testing.T) {
 
 	upstream := &staticUpstream{
 		from: ".",
+		HealthCheck: healthcheck.HealthCheck{
 			Hosts:       pool(),
-		Policy:      &Random{},
-		Spray:       nil,
 			FailTimeout: 10 * time.Second,
 			Future:      60 * time.Second,
 			MaxFails:    1,
+		},
 	}
 	g := newGrpcClient(nil, upstream)
 	upstream.ex = g

middleware/proxy/lookup.go

@@ -7,6 +7,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/coredns/coredns/middleware/pkg/healthcheck"
 	"github.com/coredns/coredns/request"
 
 	"github.com/miekg/dns"
@@ -25,30 +26,30 @@ func NewLookupWithOption(hosts []string, opts Options) Proxy {
 	// we should copy/make something similar.
 	upstream := &staticUpstream{
 		from: ".",
-		Hosts:       make([]*UpstreamHost, len(hosts)),
+		HealthCheck: healthcheck.HealthCheck{
-		Policy:      &Random{},
-		Spray:       nil,
 			FailTimeout: 10 * time.Second,
 			MaxFails:    3, // TODO(miek): disable error checking for simple lookups?
 			Future:      60 * time.Second,
+		},
 		ex: newDNSExWithOption(opts),
 	}
+	upstream.Hosts = make([]*healthcheck.UpstreamHost, len(hosts))
 
 	for i, host := range hosts {
-		uh := &UpstreamHost{
+		uh := &healthcheck.UpstreamHost{
 			Name:        host,
 			Conns:       0,
 			Fails:       0,
 			FailTimeout: upstream.FailTimeout,
 
-			CheckDown: func(upstream *staticUpstream) UpstreamHostDownFunc {
+			CheckDown: func(upstream *staticUpstream) healthcheck.UpstreamHostDownFunc {
-				return func(uh *UpstreamHost) bool {
+				return func(uh *healthcheck.UpstreamHost) bool {
 
 					down := false
 
-					uh.checkMu.Lock()
+					uh.CheckMu.Lock()
 					until := uh.OkUntil
-					uh.checkMu.Unlock()
+					uh.CheckMu.Unlock()
 
 					if !until.IsZero() && time.Now().After(until) {
 						down = true
@@ -120,7 +121,7 @@ func (p Proxy) lookup(state request.Request) (*dns.Msg, error) {
 				timeout = 10 * time.Second
 			}
 			atomic.AddInt32(&host.Fails, 1)
-			go func(host *UpstreamHost, timeout time.Duration) {
+			go func(host *healthcheck.UpstreamHost, timeout time.Duration) {
 				time.Sleep(timeout)
 				atomic.AddInt32(&host.Fails, -1)
 			}(host, timeout)

middleware/proxy/proxy.go

@@ -3,11 +3,11 @@ package proxy
 
 import (
 	"errors"
-	"sync"
 	"sync/atomic"
 	"time"
 
 	"github.com/coredns/coredns/middleware"
+	"github.com/coredns/coredns/middleware/pkg/healthcheck"
 	"github.com/coredns/coredns/request"
 
 	"github.com/miekg/dns"
@@ -41,7 +41,7 @@ type Upstream interface {
 	// The domain name this upstream host should be routed on.
 	From() string
 	// Selects an upstream host to be routed to.
-	Select() *UpstreamHost
+	Select() *healthcheck.UpstreamHost
 	// Checks if subpdomain is not an ignored.
 	IsAllowedDomain(string) bool
 	// Exchanger returns the exchanger to be used for this upstream.
@@ -50,45 +50,6 @@ type Upstream interface {
 	Stop() error
 }
 
-// UpstreamHostDownFunc can be used to customize how Down behaves.
-type UpstreamHostDownFunc func(*UpstreamHost) bool
-
-// UpstreamHost represents a single proxy upstream
-type UpstreamHost struct {
-	Conns             int64  // must be first field to be 64-bit aligned on 32-bit systems
-	Name              string // IP address (and port) of this upstream host
-	Fails             int32
-	FailTimeout       time.Duration
-	OkUntil           time.Time
-	CheckDown         UpstreamHostDownFunc
-	CheckURL          string
-	WithoutPathPrefix string
-	Checking          bool
-	checkMu           sync.Mutex
-}
-
-// Down checks whether the upstream host is down or not.
-// Down will try to use uh.CheckDown first, and will fall
-// back to some default criteria if necessary.
-func (uh *UpstreamHost) Down() bool {
-	if uh.CheckDown == nil {
-		// Default settings
-		fails := atomic.LoadInt32(&uh.Fails)
-		after := false
-
-		uh.checkMu.Lock()
-		until := uh.OkUntil
-		uh.checkMu.Unlock()
-
-		if !until.IsZero() && time.Now().After(until) {
-			after = true
-		}
-
-		return after || fails > 0
-	}
-	return uh.CheckDown(uh)
-}
-
 // tryDuration is how long to try upstream hosts; failures result in
 // immediate retries until this duration ends or we get a nil host.
 var tryDuration = 60 * time.Second
@@ -145,7 +106,7 @@ func (p Proxy) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (
 				timeout = 10 * time.Second
 			}
 			atomic.AddInt32(&host.Fails, 1)
-			go func(host *UpstreamHost, timeout time.Duration) {
+			go func(host *healthcheck.UpstreamHost, timeout time.Duration) {
 				time.Sleep(timeout)
 				atomic.AddInt32(&host.Fails, -1)
 			}(host, timeout)

middleware/proxy/upstream.go

@@ -2,46 +2,25 @@ package proxy
 
 import (
 	"fmt"
-	"io"
-	"io/ioutil"
-	"log"
 	"net"
-	"net/http"
-	"net/url"
 	"strconv"
 	"strings"
-	"sync"
 	"sync/atomic"
 	"time"
 
 	"github.com/coredns/coredns/middleware"
 	"github.com/coredns/coredns/middleware/pkg/dnsutil"
+	"github.com/coredns/coredns/middleware/pkg/healthcheck"
 	"github.com/coredns/coredns/middleware/pkg/tls"
 	"github.com/mholt/caddy/caddyfile"
 	"github.com/miekg/dns"
 )
 
-var (
-	supportedPolicies = make(map[string]func() Policy)
-)
-
 type staticUpstream struct {
 	from string
-	stop chan struct{}  // Signals running goroutines to stop.
-	wg   sync.WaitGroup // Used to wait for running goroutines to stop.
 
-	Hosts  HostPool
+	healthcheck.HealthCheck
-	Policy Policy
-	Spray  Policy
 
-	FailTimeout time.Duration
-	MaxFails    int32
-	Future      time.Duration
-	HealthCheck struct {
-		Path     string
-		Port     string
-		Interval time.Duration
-	}
 	WithoutPathPrefix string
 	IgnoredSubDomains []string
 	ex                Exchanger
@@ -54,13 +33,11 @@ func NewStaticUpstreams(c *caddyfile.Dispenser) ([]Upstream, error) {
 	for c.Next() {
 		upstream := &staticUpstream{
 			from: ".",
-			stop:        make(chan struct{}),
+			HealthCheck: healthcheck.HealthCheck{
-			Hosts:       nil,
-			Policy:      &Random{},
-			Spray:       nil,
 				FailTimeout: 10 * time.Second,
 				MaxFails:    1,
 				Future:      60 * time.Second,
+			},
 			ex: newDNSEx(),
 		}
 
@@ -84,22 +61,22 @@ func NewStaticUpstreams(c *caddyfile.Dispenser) ([]Upstream, error) {
 			}
 		}
 
-		upstream.Hosts = make([]*UpstreamHost, len(toHosts))
+		upstream.Hosts = make([]*healthcheck.UpstreamHost, len(toHosts))
 		for i, host := range toHosts {
-			uh := &UpstreamHost{
+			uh := &healthcheck.UpstreamHost{
 				Name:        host,
 				Conns:       0,
 				Fails:       0,
 				FailTimeout: upstream.FailTimeout,
 
-				CheckDown: func(upstream *staticUpstream) UpstreamHostDownFunc {
+				CheckDown: func(upstream *staticUpstream) healthcheck.UpstreamHostDownFunc {
-					return func(uh *UpstreamHost) bool {
+					return func(uh *healthcheck.UpstreamHost) bool {
 
 						down := false
 
-						uh.checkMu.Lock()
+						uh.CheckMu.Lock()
 						until := uh.OkUntil
-						uh.checkMu.Unlock()
+						uh.CheckMu.Unlock()
 
 						if !until.IsZero() && time.Now().After(until) {
 							down = true
@@ -117,32 +94,13 @@ func NewStaticUpstreams(c *caddyfile.Dispenser) ([]Upstream, error) {
 
 			upstream.Hosts[i] = uh
 		}
+		upstream.Start()
 
-		if upstream.HealthCheck.Path != "" {
-			upstream.wg.Add(1)
-			go func() {
-				defer upstream.wg.Done()
-				upstream.HealthCheckWorker(upstream.stop)
-			}()
-		}
 		upstreams = append(upstreams, upstream)
 	}
 	return upstreams, nil
 }
 
-// Stop sends a signal to all goroutines started by this staticUpstream to exit
-// and waits for them to finish before returning.
-func (u *staticUpstream) Stop() error {
-	close(u.stop)
-	u.wg.Wait()
-	return nil
-}
-
-// RegisterPolicy adds a custom policy to the proxy.
-func RegisterPolicy(name string, policy func() Policy) {
-	supportedPolicies[name] = policy
-}
-
 func (u *staticUpstream) From() string {
 	return u.from
 }
@@ -153,7 +111,7 @@ func parseBlock(c *caddyfile.Dispenser, u *staticUpstream) error {
 		if !c.NextArg() {
 			return c.ArgErr()
 		}
-		policyCreateFunc, ok := supportedPolicies[c.Val()]
+		policyCreateFunc, ok := healthcheck.SupportedPolicies[c.Val()]
 		if !ok {
 			return c.ArgErr()
 		}
@@ -214,7 +172,7 @@ func parseBlock(c *caddyfile.Dispenser, u *staticUpstream) error {
 		}
 		u.IgnoredSubDomains = ignoredDomains
 	case "spray":
-		u.Spray = &Spray{}
+		u.Spray = &healthcheck.Spray{}
 	case "protocol":
 		encArgs := c.RemainingArgs()
 		if len(encArgs) == 0 {
@@ -259,154 +217,6 @@ func parseBlock(c *caddyfile.Dispenser, u *staticUpstream) error {
 	return nil
 }
 
-// This was moved into a thread so that each host could throw a health
-// check at the same time.  The reason for this is that if we are checking
-// 3 hosts, and the first one is gone, and we spend minutes timing out to
-// fail it, we would not have been doing any other health checks in that
-// time.  So we now have a per-host lock and a threaded health check.
-//
-// We use the Checking bool to avoid concurrent checks against the same
-// host; if one is taking a long time, the next one will find a check in
-// progress and simply return before trying.
-//
-// We are carefully avoiding having the mutex locked while we check,
-// otherwise checks will back up, potentially a lot of them if a host is
-// absent for a long time.  This arrangement makes checks quickly see if
-// they are the only one running and abort otherwise.
-func healthCheckURL(nextTs time.Time, host *UpstreamHost) {
-
-	// lock for our bool check.  We don't just defer the unlock because
-	// we don't want the lock held while http.Get runs
-	host.checkMu.Lock()
-
-	// are we mid check?  Don't run another one
-	if host.Checking {
-		host.checkMu.Unlock()
-		return
-	}
-
-	host.Checking = true
-	host.checkMu.Unlock()
-
-	//log.Printf("[DEBUG] Healthchecking %s, nextTs is %s\n", url, nextTs.Local())
-
-	// fetch that url.  This has been moved into a go func because
-	// when the remote host is not merely not serving, but actually
-	// absent, then tcp syn timeouts can be very long, and so one
-	// fetch could last several check intervals
-	if r, err := http.Get(host.CheckURL); err == nil {
-		io.Copy(ioutil.Discard, r.Body)
-		r.Body.Close()
-
-		if r.StatusCode < 200 || r.StatusCode >= 400 {
-			log.Printf("[WARNING] Host %s health check returned HTTP code %d\n",
-				host.Name, r.StatusCode)
-			nextTs = time.Unix(0, 0)
-		}
-	} else {
-		log.Printf("[WARNING] Host %s health check probe failed: %v\n", host.Name, err)
-		nextTs = time.Unix(0, 0)
-	}
-
-	host.checkMu.Lock()
-	host.Checking = false
-	host.OkUntil = nextTs
-	host.checkMu.Unlock()
-}
-
-func (u *staticUpstream) healthCheck() {
-	for _, host := range u.Hosts {
-
-		if host.CheckURL == "" {
-			var hostName, checkPort string
-
-			// The DNS server might be an HTTP server.  If so, extract its name.
-			ret, err := url.Parse(host.Name)
-			if err == nil && len(ret.Host) > 0 {
-				hostName = ret.Host
-			} else {
-				hostName = host.Name
-			}
-
-			// Extract the port number from the parsed server name.
-			checkHostName, checkPort, err := net.SplitHostPort(hostName)
-			if err != nil {
-				checkHostName = hostName
-			}
-
-			if u.HealthCheck.Port != "" {
-				checkPort = u.HealthCheck.Port
-			}
-
-			host.CheckURL = "http://" + net.JoinHostPort(checkHostName, checkPort) + u.HealthCheck.Path
-		}
-
-		// calculate this before the get
-		nextTs := time.Now().Add(u.Future)
-
-		// locks/bools should prevent requests backing up
-		go healthCheckURL(nextTs, host)
-	}
-}
-
-func (u *staticUpstream) HealthCheckWorker(stop chan struct{}) {
-	ticker := time.NewTicker(u.HealthCheck.Interval)
-	u.healthCheck()
-	for {
-		select {
-		case <-ticker.C:
-			u.healthCheck()
-		case <-stop:
-			ticker.Stop()
-			return
-		}
-	}
-}
-
-func (u *staticUpstream) Select() *UpstreamHost {
-	pool := u.Hosts
-	if len(pool) == 1 {
-		if pool[0].Down() && u.Spray == nil {
-			return nil
-		}
-		return pool[0]
-	}
-	allDown := true
-	for _, host := range pool {
-		if !host.Down() {
-			allDown = false
-			break
-		}
-	}
-	if allDown {
-		if u.Spray == nil {
-			return nil
-		}
-		return u.Spray.Select(pool)
-	}
-
-	if u.Policy == nil {
-		h := (&Random{}).Select(pool)
-		if h != nil {
-			return h
-		}
-		if h == nil && u.Spray == nil {
-			return nil
-		}
-		return u.Spray.Select(pool)
-	}
-
-	h := u.Policy.Select(pool)
-	if h != nil {
-		return h
-	}
-
-	if u.Spray == nil {
-		return nil
-	}
-	return u.Spray.Select(pool)
-}
-
 func (u *staticUpstream) IsAllowedDomain(name string) bool {
 	if dns.Name(name) == dns.Name(u.From()) {
 		return true

middleware/proxy/upstream_test.go

@@ -2,74 +2,16 @@ package proxy
 
 import (
 	"io/ioutil"
-	"log"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
-	"time"
 
 	"github.com/coredns/coredns/middleware/test"
 
 	"github.com/mholt/caddy"
 )
 
-func TestHealthCheck(t *testing.T) {
-	log.SetOutput(ioutil.Discard)
-
-	upstream := &staticUpstream{
-		from:        ".",
-		Hosts:       testPool(),
-		Policy:      &Random{},
-		Spray:       nil,
-		FailTimeout: 10 * time.Second,
-		Future:      60 * time.Second,
-		MaxFails:    1,
-	}
-
-	upstream.healthCheck()
-	// sleep a bit, it's async now
-	time.Sleep(time.Duration(2 * time.Second))
-
-	if upstream.Hosts[0].Down() {
-		t.Error("Expected first host in testpool to not fail healthcheck.")
-	}
-	if !upstream.Hosts[1].Down() {
-		t.Error("Expected second host in testpool to fail healthcheck.")
-	}
-}
-
-func TestSelect(t *testing.T) {
-	upstream := &staticUpstream{
-		from:        ".",
-		Hosts:       testPool()[:3],
-		Policy:      &Random{},
-		FailTimeout: 10 * time.Second,
-		Future:      60 * time.Second,
-		MaxFails:    1,
-	}
-	upstream.Hosts[0].OkUntil = time.Unix(0, 0)
-	upstream.Hosts[1].OkUntil = time.Unix(0, 0)
-	upstream.Hosts[2].OkUntil = time.Unix(0, 0)
-	if h := upstream.Select(); h != nil {
-		t.Error("Expected select to return nil as all host are down")
-	}
-	upstream.Hosts[2].OkUntil = time.Time{}
-	if h := upstream.Select(); h == nil {
-		t.Error("Expected select to not return nil")
-	}
-}
-
-func TestRegisterPolicy(t *testing.T) {
-	name := "custom"
-	customPolicy := &customPolicy{}
-	RegisterPolicy(name, func() Policy { return customPolicy })
-	if _, ok := supportedPolicies[name]; !ok {
-		t.Error("Expected supportedPolicies to have a custom policy.")
-	}
-
-}
-
 func TestAllowedDomain(t *testing.T) {
 	upstream := &staticUpstream{
 		from:              "miek.nl.",