traefik/pkg/healthcheck/healthcheck.go

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package healthcheck
import (
"context"
"errors"
"fmt"
"net"
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"net/http"
"net/url"
"strconv"
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"time"
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gokitmetrics "github.com/go-kit/kit/metrics"
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"github.com/rs/zerolog/log"
"github.com/traefik/traefik/v2/pkg/config/dynamic"
"github.com/traefik/traefik/v2/pkg/config/runtime"
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"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/credentials/insecure"
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healthpb "google.golang.org/grpc/health/grpc_health_v1"
"google.golang.org/grpc/status"
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)
const modeGRPC = "grpc"
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// StatusSetter should be implemented by a service that, when the status of a
// registered target change, needs to be notified of that change.
type StatusSetter interface {
SetStatus(ctx context.Context, childName string, up bool)
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}
// StatusUpdater should be implemented by a service that, when its status
// changes (e.g. all if its children are down), needs to propagate upwards (to
// their parent(s)) that change.
type StatusUpdater interface {
RegisterStatusUpdater(fn func(up bool)) error
}
type metricsHealthCheck interface {
ServiceServerUpGauge() gokitmetrics.Gauge
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}
type ServiceHealthChecker struct {
balancer StatusSetter
info *runtime.ServiceInfo
config *dynamic.ServerHealthCheck
interval time.Duration
timeout time.Duration
metrics metricsHealthCheck
client *http.Client
targets map[string]*url.URL
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}
func NewServiceHealthChecker(ctx context.Context, metrics metricsHealthCheck, config *dynamic.ServerHealthCheck, service StatusSetter, info *runtime.ServiceInfo, transport http.RoundTripper, targets map[string]*url.URL) *ServiceHealthChecker {
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logger := log.Ctx(ctx)
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interval := time.Duration(config.Interval)
if interval <= 0 {
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logger.Error().Msg("Health check interval smaller than zero")
interval = time.Duration(dynamic.DefaultHealthCheckInterval)
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}
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timeout := time.Duration(config.Timeout)
if timeout <= 0 {
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logger.Error().Msg("Health check timeout smaller than zero")
timeout = time.Duration(dynamic.DefaultHealthCheckTimeout)
}
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if timeout >= interval {
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logger.Warn().Msgf("Health check timeout should be lower than the health check interval. Interval set to timeout + 1 second (%s).", interval)
interval = timeout + time.Second
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}
client := &http.Client{
Transport: transport,
}
if config.FollowRedirects != nil && !*config.FollowRedirects {
client.CheckRedirect = func(req *http.Request, via []*http.Request) error {
return http.ErrUseLastResponse
}
}
return &ServiceHealthChecker{
balancer: service,
info: info,
config: config,
interval: interval,
timeout: timeout,
targets: targets,
client: client,
metrics: metrics,
}
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}
func (shc *ServiceHealthChecker) Launch(ctx context.Context) {
ticker := time.NewTicker(shc.interval)
defer ticker.Stop()
for {
select {
case <-ctx.Done():
return
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case <-ticker.C:
for proxyName, target := range shc.targets {
select {
case <-ctx.Done():
return
default:
}
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up := true
serverUpMetricValue := float64(1)
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if err := shc.executeHealthCheck(ctx, shc.config, target); err != nil {
// The context is canceled when the dynamic configuration is refreshed.
if errors.Is(err, context.Canceled) {
return
}
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log.Ctx(ctx).Warn().
Str("targetURL", target.String()).
Err(err).
Msg("Health check failed.")
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up = false
serverUpMetricValue = float64(0)
}
shc.balancer.SetStatus(ctx, proxyName, up)
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statusStr := runtime.StatusDown
if up {
statusStr = runtime.StatusUp
}
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shc.info.UpdateServerStatus(target.String(), statusStr)
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shc.metrics.ServiceServerUpGauge().
With("service", proxyName, "url", target.String()).
Set(serverUpMetricValue)
}
}
}
}
func (shc *ServiceHealthChecker) executeHealthCheck(ctx context.Context, config *dynamic.ServerHealthCheck, target *url.URL) error {
ctx, cancel := context.WithDeadline(ctx, time.Now().Add(shc.timeout))
defer cancel()
if config.Mode == modeGRPC {
return shc.checkHealthGRPC(ctx, target)
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}
return shc.checkHealthHTTP(ctx, target)
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}
// checkHealthHTTP returns an error with a meaningful description if the health check failed.
// Dedicated to HTTP servers.
func (shc *ServiceHealthChecker) checkHealthHTTP(ctx context.Context, target *url.URL) error {
req, err := shc.newRequest(ctx, target)
if err != nil {
return fmt.Errorf("create HTTP request: %w", err)
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}
resp, err := shc.client.Do(req)
if err != nil {
return fmt.Errorf("HTTP request failed: %w", err)
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}
defer resp.Body.Close()
if shc.config.Status == 0 && (resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusBadRequest) {
return fmt.Errorf("received error status code: %v", resp.StatusCode)
}
if shc.config.Status != 0 && shc.config.Status != resp.StatusCode {
return fmt.Errorf("received error status code: %v expected status code: %v", resp.StatusCode, shc.config.Status)
}
return nil
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}
func (shc *ServiceHealthChecker) newRequest(ctx context.Context, target *url.URL) (*http.Request, error) {
u, err := target.Parse(shc.config.Path)
if err != nil {
return nil, err
}
if len(shc.config.Scheme) > 0 {
u.Scheme = shc.config.Scheme
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}
if shc.config.Port != 0 {
u.Host = net.JoinHostPort(u.Hostname(), strconv.Itoa(shc.config.Port))
}
req, err := http.NewRequestWithContext(ctx, shc.config.Method, u.String(), http.NoBody)
if err != nil {
return nil, fmt.Errorf("failed to create HTTP request: %w", err)
}
if shc.config.Hostname != "" {
req.Host = shc.config.Hostname
}
for k, v := range shc.config.Headers {
req.Header.Set(k, v)
}
return req, nil
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}
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// checkHealthGRPC returns an error with a meaningful description if the health check failed.
// Dedicated to gRPC servers implementing gRPC Health Checking Protocol v1.
func (shc *ServiceHealthChecker) checkHealthGRPC(ctx context.Context, serverURL *url.URL) error {
u, err := serverURL.Parse(shc.config.Path)
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if err != nil {
return fmt.Errorf("failed to parse server URL: %w", err)
}
port := u.Port()
if shc.config.Port != 0 {
port = strconv.Itoa(shc.config.Port)
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}
serverAddr := net.JoinHostPort(u.Hostname(), port)
var opts []grpc.DialOption
switch shc.config.Scheme {
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case "http", "h2c", "":
opts = append(opts, grpc.WithTransportCredentials(insecure.NewCredentials()))
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}
conn, err := grpc.DialContext(ctx, serverAddr, opts...)
if err != nil {
if errors.Is(err, context.DeadlineExceeded) {
return fmt.Errorf("fail to connect to %s within %s: %w", serverAddr, shc.config.Timeout, err)
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}
return fmt.Errorf("fail to connect to %s: %w", serverAddr, err)
}
defer func() { _ = conn.Close() }()
resp, err := healthpb.NewHealthClient(conn).Check(ctx, &healthpb.HealthCheckRequest{})
if err != nil {
if stat, ok := status.FromError(err); ok {
switch stat.Code() {
case codes.Unimplemented:
return fmt.Errorf("gRPC server does not implement the health protocol: %w", err)
case codes.DeadlineExceeded:
return fmt.Errorf("gRPC health check timeout: %w", err)
case codes.Canceled:
return context.Canceled
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}
}
return fmt.Errorf("gRPC health check failed: %w", err)
}
if resp.Status != healthpb.HealthCheckResponse_SERVING {
return fmt.Errorf("received gRPC status code: %v", resp.Status)
}
return nil
}