traefik/healthcheck/healthcheck.go

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package healthcheck
import (
"context"
"fmt"
"net"
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"net/http"
"net/url"
"strconv"
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"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 {
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Path string
Port int
Transport http.RoundTripper
Interval time.Duration
LB LoadBalancer
}
func (opt Options) String() string {
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return fmt.Sprintf("[Path: %s Port: %d Interval: %s]", opt.Path, opt.Port, opt.Interval)
}
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// BackendHealthCheck HealthCheck configuration for a backend
type BackendHealthCheck struct {
Options
name string
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, backendName string) *BackendHealthCheck {
return &BackendHealthCheck{
Options: options,
name: backendName,
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 _, backend := range backends {
currentBackend := backend
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safe.Go(func() {
hc.execute(ctx, currentBackend)
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})
}
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}
func (hc *HealthCheck) execute(ctx context.Context, backend *BackendHealthCheck) {
log.Debugf("Initial health check for backend: %q", backend.name)
hc.checkBackend(backend)
ticker := time.NewTicker(backend.Interval)
defer ticker.Stop()
for {
select {
case <-ctx.Done():
log.Debug("Stopping current health check goroutines of backend: %s", backend.name)
return
case <-ticker.C:
log.Debugf("Refreshing health check for backend: %s", backend.name)
hc.checkBackend(backend)
}
}
}
func (hc *HealthCheck) checkBackend(backend *BackendHealthCheck) {
enabledURLs := backend.LB.Servers()
var newDisabledURLs []*url.URL
for _, url := range backend.disabledURLs {
if err := checkHealth(url, backend); err == nil {
log.Warnf("Health check up: Returning to server list. Backend: %q URL: %q", backend.name, url.String())
backend.LB.UpsertServer(url, roundrobin.Weight(1))
} else {
log.Warnf("Health check still failing. Backend: %q URL: %q Reason: %s", backend.name, url.String(), err)
newDisabledURLs = append(newDisabledURLs, url)
}
}
backend.disabledURLs = newDisabledURLs
for _, url := range enabledURLs {
if err := checkHealth(url, backend); err != nil {
log.Warnf("Health check failed: Remove from server list. Backend: %q URL: %q Reason: %s", backend.name, url.String(), err)
backend.LB.RemoveServer(url)
backend.disabledURLs = append(backend.disabledURLs, url)
}
}
}
func (backend *BackendHealthCheck) newRequest(serverURL *url.URL) (*http.Request, error) {
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if backend.Port == 0 {
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return http.NewRequest(http.MethodGet, serverURL.String()+backend.Path, nil)
}
// copy the url and add the port to the host
u := &url.URL{}
*u = *serverURL
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u.Host = net.JoinHostPort(u.Hostname(), strconv.Itoa(backend.Port))
u.Path = u.Path + backend.Path
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return http.NewRequest(http.MethodGet, u.String(), nil)
}
// checkHealth returns a nil error in case it was successful and otherwise
// a non-nil error with a meaningful description why the health check failed.
func checkHealth(serverURL *url.URL, backend *BackendHealthCheck) error {
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client := http.Client{
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Timeout: backend.requestTimeout,
Transport: backend.Options.Transport,
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}
req, err := backend.newRequest(serverURL)
if err != nil {
return fmt.Errorf("failed to create HTTP request: %s", err)
}
resp, err := client.Do(req)
if err == nil {
defer resp.Body.Close()
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}
switch {
case err != nil:
return fmt.Errorf("HTTP request failed: %s", err)
case resp.StatusCode != http.StatusOK:
return fmt.Errorf("received non-200 status code: %v", resp.StatusCode)
}
return nil
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}