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Remove pkg/healthcheck (#2678)

Browse Source 
This now lives on coredns/proxy

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben
2019-03-12 12:51:34 +00:00
committed by GitHub
parent 2ffcef1071
commit b602f3ed06
4 changed files with 0 additions and 542 deletions
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241
plugin/pkg/healthcheck/healthcheck.go
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@@ -1,241 +0,0 @@
package healthcheck
import (
"io"
"io/ioutil"
"net"
"net/http"
"net/url"
"sync"
"sync/atomic"
"time"
"github.com/coredns/coredns/plugin/pkg/log"
)
// 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
CheckDown UpstreamHostDownFunc
CheckURL string
Checking bool
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 {
fails := atomic.LoadInt32(&uh.Fails)
return fails > 0
}
return uh.CheckDown(uh)
}
// HostPool is a collection of UpstreamHosts.
type HostPool []*UpstreamHost
// HealthCheck is used for performing healthcheck
// on a collection of upstream hosts and select
// one based on the policy.
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
Path string
Port string
Interval time.Duration
}
// Start starts the healthcheck
func (u *HealthCheck) Start() {
for i, h := range u.Hosts {
u.Hosts[i].CheckURL = u.normalizeCheckURL(h.Name)
}
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.
// HealthCheckURL performs the http.Get that implements healthcheck.
func (uh *UpstreamHost) HealthCheckURL() {
// Lock for our bool check. We don't just defer the unlock because
// we don't want the lock held while http.Get runs.
uh.Lock()
// We call HealthCheckURL from proxy.go and lookup.go, bail out when nothing
// is configured to healthcheck. Or we mid check? Don't run another one.
if uh.CheckURL == "" || uh.Checking { // nothing configured
uh.Unlock()
return
}
uh.Checking = true
uh.Unlock()
// default timeout (5s)
r, err := healthClient.Get(uh.CheckURL)
defer func() {
uh.Lock()
uh.Checking = false
uh.Unlock()
}()
if err != nil {
log.Warningf("Host %s health check probe failed: %v", uh.Name, err)
atomic.AddInt32(&uh.Fails, 1)
return
}
if err == nil {
io.Copy(ioutil.Discard, r.Body)
r.Body.Close()
if r.StatusCode < 200 || r.StatusCode >= 400 {
log.Warningf("Host %s health check returned HTTP code %d", uh.Name, r.StatusCode)
atomic.AddInt32(&uh.Fails, 1)
return
}
// We are healthy again, reset fails.
atomic.StoreInt32(&uh.Fails, 0)
return
}
}
func (u *HealthCheck) healthCheck() {
for _, host := range u.Hosts {
// locks/bools should prevent requests backing up
go host.HealthCheckURL()
}
}
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
}
}
}
// Select selects an upstream host based on the policy
// and the healthcheck result.
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)
}
// normalizeCheckURL creates a proper URL for the health check.
func (u *HealthCheck) normalizeCheckURL(name string) string {
if u.Path == "" {
return ""
}
// The DNS server might be an HTTP server. If so, extract its name.
hostName := name
ret, err := url.Parse(name)
if err == nil && len(ret.Host) > 0 {
hostName = ret.Host
}
// 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
}
checkURL := "http://" + net.JoinHostPort(checkHostName, checkPort) + u.Path
return checkURL
}
var healthClient = func() *http.Client { return &http.Client{Timeout: 5 * time.Second} }()

5
plugin/pkg/healthcheck/log_test.go
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@@ -1,5 +0,0 @@
package healthcheck
import clog "github.com/coredns/coredns/plugin/pkg/log"
func init() { clog.Discard() }

141
plugin/pkg/healthcheck/policy.go
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@@ -1,141 +0,0 @@
package healthcheck
import (
"math/rand"
"sync/atomic"
"github.com/coredns/coredns/plugin/pkg/log"
)
var (
// SupportedPolicies is the collection of policies registered
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
// no traffic to go through at all.
type Policy interface {
Select(pool HostPool) *UpstreamHost
}
func init() {
RegisterPolicy("random", func() Policy { return &Random{} })
RegisterPolicy("least_conn", func() Policy { return &LeastConn{} })
RegisterPolicy("round_robin", func() Policy { return &RoundRobin{} })
RegisterPolicy("first", func() Policy { return &First{} })
// 'sequential' is an alias to 'first' to maintain consistency with the forward plugin
// should probably remove 'first' in a future release
RegisterPolicy("sequential", func() Policy { return &First{} })
}
// Random is a policy that selects up hosts from a pool at random.
type Random struct{}
// Select selects an up host at random from the specified pool.
func (r *Random) Select(pool HostPool) *UpstreamHost {
// instead of just generating a random index
// this is done to prevent selecting a down host
var randHost *UpstreamHost
count := 0
for _, host := range pool {
if host.Down() {
continue
}
count++
if count == 1 {
randHost = host
} else {
r := rand.Int() % count
if r == (count - 1) {
randHost = host
}
}
}
return randHost
}
// Spray is a policy that selects a host from a pool at random. This should be used as a last ditch
// attempt to get a host when all hosts are reporting unhealthy.
type Spray struct{}
// Select selects an up host at random from the specified pool.
func (r *Spray) Select(pool HostPool) *UpstreamHost {
rnd := rand.Int() % len(pool)
randHost := pool[rnd]
log.Warningf("All hosts reported as down, spraying to target: %s", randHost.Name)
return randHost
}
// LeastConn is a policy that selects the host with the least connections.
type LeastConn struct{}
// Select selects the up host with the least number of connections in the
// pool. If more than one host has the same least number of connections,
// one of the hosts is chosen at random.
func (r *LeastConn) Select(pool HostPool) *UpstreamHost {
var bestHost *UpstreamHost
count := 0
leastConn := int64(1<<63 - 1)
for _, host := range pool {
if host.Down() {
continue
}
hostConns := host.Conns
if hostConns < leastConn {
bestHost = host
leastConn = hostConns
count = 1
} else if hostConns == leastConn {
// randomly select host among hosts with least connections
count++
if count == 1 {
bestHost = host
} else {
r := rand.Int() % count
if r == (count - 1) {
bestHost = host
}
}
}
}
return bestHost
}
// RoundRobin is a policy that selects hosts based on round robin ordering.
type RoundRobin struct {
Robin uint32
}
// Select selects an up host from the pool using a round robin ordering scheme.
func (r *RoundRobin) Select(pool HostPool) *UpstreamHost {
poolLen := uint32(len(pool))
selection := atomic.AddUint32(&r.Robin, 1) % poolLen
host := pool[selection]
// if the currently selected host is down, just ffwd to up host
for i := uint32(1); host.Down() && i < poolLen; i++ {
host = pool[(selection+i)%poolLen]
}
return host
}
// First is a policy that selects always the first healthy host in the list order.
type First struct{}
// Select always the first that is not Down.
func (r *First) Select(pool HostPool) *UpstreamHost {
for i := 0; i < len(pool); i++ {
host := pool[i]
if host.Down() {
continue
}
return host
}
// return the first one, anyway none is correct
return nil
}

155
plugin/pkg/healthcheck/policy_test.go
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@@ -1,155 +0,0 @@
package healthcheck
import (
"net/http"
"net/http/httptest"
"os"
"testing"
"time"
)
var workableServer *httptest.Server
func TestMain(m *testing.M) {
workableServer = httptest.NewServer(http.HandlerFunc(
func(w http.ResponseWriter, r *http.Request) {
// do nothing
}))
r := m.Run()
workableServer.Close()
os.Exit(r)
}
type customPolicy struct{}
func (r *customPolicy) Select(pool HostPool) *UpstreamHost {
return pool[0]
}
func testPool() HostPool {
pool := []*UpstreamHost{
{Name: workableServer.URL}, // this should resolve (healthcheck test)
{Name: "http://shouldnot.resolve:85"}, // this shouldn't, especially on port other than 80
{Name: "http://C"},
}
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) {
u := &HealthCheck{
Hosts: testPool(),
Path: "/",
FailTimeout: 10 * time.Second,
MaxFails: 1,
}
for i, h := range u.Hosts {
u.Hosts[i].CheckURL = u.normalizeCheckURL(h.Name)
}
u.healthCheck()
time.Sleep(time.Duration(1 * time.Second)) // sleep a bit, it's async now
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 TestHealthCheckDisabled(t *testing.T) {
u := &HealthCheck{
Hosts: testPool(),
FailTimeout: 10 * time.Second,
MaxFails: 1,
}
for i, h := range u.Hosts {
u.Hosts[i].CheckURL = u.normalizeCheckURL(h.Name)
}
u.healthCheck()
time.Sleep(time.Duration(1 * time.Second)) // sleep a bit, it's async now
for i, h := range u.Hosts {
if h.Down() {
t.Errorf("Expected host %d in testpool to not be down with healthchecks disabled.", i+1)
}
}
}
func TestRoundRobinPolicy(t *testing.T) {
pool := testPool()
rrPolicy := &RoundRobin{}
h := rrPolicy.Select(pool)
// First selected host is 1, because counter starts at 0
// and increments before host is selected
if h != pool[1] {
t.Error("Expected first round robin host to be second host in the pool.")
}
h = rrPolicy.Select(pool)
if h != pool[2] {
t.Error("Expected second round robin host to be third host in the pool.")
}
h = rrPolicy.Select(pool)
if h != pool[0] {
t.Error("Expected third round robin host to be first host in the pool.")
}
}
func TestLeastConnPolicy(t *testing.T) {
pool := testPool()
lcPolicy := &LeastConn{}
pool[0].Conns = 10
pool[1].Conns = 10
h := lcPolicy.Select(pool)
if h != pool[2] {
t.Error("Expected least connection host to be third host.")
}
pool[2].Conns = 100
h = lcPolicy.Select(pool)
if h != pool[0] && h != pool[1] {
t.Error("Expected least connection host to be first or second host.")
}
}
func TestCustomPolicy(t *testing.T) {
pool := testPool()
customPolicy := &customPolicy{}
h := customPolicy.Select(pool)
if h != pool[0] {
t.Error("Expected custom policy host to be the first host.")
}
}
func TestFirstPolicy(t *testing.T) {
pool := testPool()
rrPolicy := &First{}
h := rrPolicy.Select(pool)
// First selected host is 1, because counter starts at 0
// and increments before host is selected
if h != pool[0] {
t.Error("Expected always first to be first host in the pool.")
}
h = rrPolicy.Select(pool)
if h != pool[0] {
t.Error("Expected always first to be first host in the pool, even in second call")
}
// set this first in pool as failed
pool[0].Fails = 1
h = rrPolicy.Select(pool)
if h != pool[1] {
t.Error("Expected first to be he second in pool if the first one is down.")
}
}