traefik/healthcheck/healthcheck.go

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package healthcheck
import (
"context"
"fmt"
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"net/http"
"net/url"
"sync"
"time"
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"github.com/containous/traefik/log"
"github.com/containous/traefik/safe"
"github.com/vulcand/oxy/roundrobin"
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)
var singleton *HealthCheck
var once sync.Once
// GetHealthCheck returns the health check which is guaranteed to be a singleton.
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func GetHealthCheck() *HealthCheck {
once.Do(func() {
singleton = newHealthCheck()
})
return singleton
}
// Options are the public health check options.
type Options struct {
Path string
Interval time.Duration
LB LoadBalancer
}
func (opt Options) String() string {
return fmt.Sprintf("[Path: %s Interval: %s]", opt.Path, opt.Interval)
}
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// BackendHealthCheck HealthCheck configuration for a backend
type BackendHealthCheck struct {
Options
disabledURLs []*url.URL
requestTimeout time.Duration
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}
//HealthCheck struct
type HealthCheck struct {
Backends map[string]*BackendHealthCheck
cancel context.CancelFunc
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}
// LoadBalancer includes functionality for load-balancing management.
type LoadBalancer interface {
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RemoveServer(u *url.URL) error
UpsertServer(u *url.URL, options ...roundrobin.ServerOption) error
Servers() []*url.URL
}
func newHealthCheck() *HealthCheck {
return &HealthCheck{
Backends: make(map[string]*BackendHealthCheck),
}
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}
// NewBackendHealthCheck Instantiate a new BackendHealthCheck
func NewBackendHealthCheck(options Options) *BackendHealthCheck {
return &BackendHealthCheck{
Options: options,
requestTimeout: 5 * time.Second,
}
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}
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//SetBackendsConfiguration set backends configuration
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func (hc *HealthCheck) SetBackendsConfiguration(parentCtx context.Context, backends map[string]*BackendHealthCheck) {
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hc.Backends = backends
if hc.cancel != nil {
hc.cancel()
}
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ctx, cancel := context.WithCancel(parentCtx)
hc.cancel = cancel
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for backendID, backend := range hc.Backends {
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currentBackendID := backendID
currentBackend := backend
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safe.Go(func() {
hc.execute(ctx, currentBackendID, currentBackend)
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})
}
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}
func (hc *HealthCheck) execute(ctx context.Context, backendID string, backend *BackendHealthCheck) {
log.Debugf("Initial healthcheck for currentBackend %s ", backendID)
checkBackend(backend)
ticker := time.NewTicker(backend.Interval)
defer ticker.Stop()
for {
select {
case <-ctx.Done():
log.Debugf("Stopping all current Healthcheck goroutines")
return
case <-ticker.C:
log.Debugf("Refreshing healthcheck for currentBackend %s ", backendID)
checkBackend(backend)
}
}
}
func checkBackend(currentBackend *BackendHealthCheck) {
enabledURLs := currentBackend.LB.Servers()
var newDisabledURLs []*url.URL
for _, url := range currentBackend.disabledURLs {
if checkHealth(url, currentBackend) {
log.Debugf("HealthCheck is up [%s]: Upsert in server list", url.String())
currentBackend.LB.UpsertServer(url, roundrobin.Weight(1))
} else {
log.Warnf("HealthCheck is still failing [%s]", url.String())
newDisabledURLs = append(newDisabledURLs, url)
}
}
currentBackend.disabledURLs = newDisabledURLs
for _, url := range enabledURLs {
if !checkHealth(url, currentBackend) {
log.Warnf("HealthCheck has failed [%s]: Remove from server list", url.String())
currentBackend.LB.RemoveServer(url)
currentBackend.disabledURLs = append(currentBackend.disabledURLs, url)
}
}
}
func checkHealth(serverURL *url.URL, backend *BackendHealthCheck) bool {
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client := http.Client{
Timeout: backend.requestTimeout,
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}
resp, err := client.Get(serverURL.String() + backend.Path)
if err == nil {
defer resp.Body.Close()
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}
return err == nil && resp.StatusCode == 200
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}