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healthcheck.go
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healthcheck.go
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package healthcheck
import (
"context"
"fmt"
"net"
"net/http"
"net/url"
"strconv"
"sync"
"time"
"github.com/containous/traefik/log"
"github.com/containous/traefik/safe"
"github.com/vulcand/oxy/roundrobin"
)
var singleton *HealthCheck
var once sync.Once
// GetHealthCheck returns the health check which is guaranteed to be a singleton.
func GetHealthCheck() *HealthCheck {
once.Do(func() {
singleton = newHealthCheck()
})
return singleton
}
// Options are the public health check options.
type Options struct {
Path string
Port int
Interval time.Duration
LB LoadBalancer
}
func (opt Options) String() string {
return fmt.Sprintf("[Path: %s Port: %d Interval: %s]", opt.Path, opt.Port, opt.Interval)
}
// BackendHealthCheck HealthCheck configuration for a backend
type BackendHealthCheck struct {
Options
disabledURLs []*url.URL
requestTimeout time.Duration
}
//HealthCheck struct
type HealthCheck struct {
Backends map[string]*BackendHealthCheck
cancel context.CancelFunc
}
// LoadBalancer includes functionality for load-balancing management.
type LoadBalancer interface {
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),
}
}
// NewBackendHealthCheck Instantiate a new BackendHealthCheck
func NewBackendHealthCheck(options Options) *BackendHealthCheck {
return &BackendHealthCheck{
Options: options,
requestTimeout: 5 * time.Second,
}
}
//SetBackendsConfiguration set backends configuration
func (hc *HealthCheck) SetBackendsConfiguration(parentCtx context.Context, backends map[string]*BackendHealthCheck) {
hc.Backends = backends
if hc.cancel != nil {
hc.cancel()
}
ctx, cancel := context.WithCancel(parentCtx)
hc.cancel = cancel
for backendID, backend := range hc.Backends {
currentBackendID := backendID
currentBackend := backend
safe.Go(func() {
hc.execute(ctx, currentBackendID, currentBackend)
})
}
}
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.Debug("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 (backend *BackendHealthCheck) newRequest(serverURL *url.URL) (*http.Request, error) {
if backend.Port == 0 {
return http.NewRequest("GET", serverURL.String()+backend.Path, nil)
}
// copy the url and add the port to the host
u := &url.URL{}
*u = *serverURL
u.Host = net.JoinHostPort(u.Hostname(), strconv.Itoa(backend.Port))
u.Path = u.Path + backend.Path
return http.NewRequest("GET", u.String(), nil)
}
func checkHealth(serverURL *url.URL, backend *BackendHealthCheck) bool {
client := http.Client{
Timeout: backend.requestTimeout,
}
req, err := backend.newRequest(serverURL)
if err != nil {
log.Errorf("Failed to create HTTP request [%s] for healthcheck: %s", serverURL, err)
return false
}
resp, err := client.Do(req)
if err == nil {
defer resp.Body.Close()
}
return err == nil && resp.StatusCode == 200
}