cilium-envoy-hook/cmd/server.go

package cmd

import (
	"context"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/oklog/run"
	"github.com/spf13/cobra"
	"go.uber.org/zap"

	kwhhttp "github.com/slok/kubewebhook/v2/pkg/http"
	"github.com/slok/kubewebhook/v2/pkg/log"
	kwhmutating "github.com/slok/kubewebhook/v2/pkg/webhook/mutating"

	kwhmodel "github.com/slok/kubewebhook/v2/pkg/model"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

type wrapLogger struct {
	*zap.SugaredLogger
}

func (n *wrapLogger) WithValues(map[string]interface{}) log.Logger { return n }
func (n *wrapLogger) WithCtxValues(context.Context) log.Logger     { return n }
func (n *wrapLogger) SetValuesOnCtx(parent context.Context, values map[string]interface{}) context.Context {
	return parent
}
func (n *wrapLogger) Warningf(template string, args ...interface{}) {
	n.Warnf(template, args...)
}

type CmdConfig struct {
	WebhookListenAddr       string
	TLSCertFilePath         string
	TLSKeyFilePath          string
	EnableIngressSingleHost bool
	IngressHostRegexes      []string
	MinSMScrapeInterval     time.Duration

	LabelMarks map[string]string
}

var (
	cmdConfig = &CmdConfig{
		LabelMarks: map[string]string{},
	}
	serverCmd = &cobra.Command{
		Use: "server",
		Run: func(cmd *cobra.Command, args []string) {
			var err error
			logger := zap.L()

			var g run.Group

			// OS signals.
			{
				sigC := make(chan os.Signal, 1)
				exitC := make(chan struct{})
				signal.Notify(sigC, syscall.SIGTERM, syscall.SIGINT)

				g.Add(
					func() error {
						select {
						case s := <-sigC:
							logger.Sugar().Info("signal %s received", s)
							return nil
						case <-exitC:
							return nil
						}
					},
					func(_ error) {
						close(exitC)
					},
				)
			}

			// Webhook HTTP server.
			{
				logger := logger.With(zap.String("addr", cmdConfig.WebhookListenAddr), zap.String("http-server", "webhooks"))
				mt := kwhmutating.MutatorFunc(func(_ context.Context, _ *kwhmodel.AdmissionReview, obj metav1.Object) (*kwhmutating.MutatorResult, error) {
					logger.Info("mutating webhook called", zap.Any("object", obj))
					return &kwhmutating.MutatorResult{MutatedObject: obj}, nil
				})

				// Create webhook.
				wh, err := kwhmutating.NewWebhook(kwhmutating.WebhookConfig{
					ID:      "mutator.cilium-envoy-hook.io",
					Mutator: mt,
					Logger:  &wrapLogger{logger.Sugar()},
				})
				if err != nil {
					logger.Fatal("error creating webhook", zap.Error(err))
				}

				// Get HTTP handler from webhook.
				whHandler, err := kwhhttp.HandlerFor(kwhhttp.HandlerConfig{Webhook: wh, Logger: &wrapLogger{logger.Sugar()}})
				if err != nil {
					logger.Fatal("error creating webhook handler", zap.Error(err))
				}

				server := &http.Server{
					Addr:    cmdConfig.WebhookListenAddr,
					Handler: whHandler,
				}

				g.Add(
					func() error {
						if cmdConfig.TLSCertFilePath == "" || cmdConfig.TLSKeyFilePath == "" {
							logger.Warn("webhook running without TLS")
							logger.Info("http server listening...")
							return server.ListenAndServe()
						}

						logger.Info("https server listening...")
						return server.ListenAndServeTLS(cmdConfig.TLSCertFilePath, cmdConfig.TLSKeyFilePath)
					},
					func(_ error) {
						logger.Info("start draining connections")
						ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
						defer cancel()

						err := server.Shutdown(ctx)
						if err != nil {
							logger.Error("error while shutting down the server", zap.Error(err))
						} else {
							logger.Info("server stopped")
						}
					},
				)
			}

			err = g.Run()
			if err != nil {
				logger.Fatal("error while running the application", zap.Error(err))
			}
		},
	}
)

func init() {
	rootCmd.AddCommand(serverCmd)

	serverCmd.PersistentFlags().StringVar(&cmdConfig.WebhookListenAddr, "webhook-listen-address", ":8080", "The address where the HTTPS server will be listening to serve the webhooks.")
	serverCmd.PersistentFlags().StringVar(&cmdConfig.TLSCertFilePath, "tls-cert-file-path", "", "The path for the webhook HTTPS server TLS cert file.")
	serverCmd.PersistentFlags().StringVar(&cmdConfig.TLSKeyFilePath, "tls-key-file-path", "", "The path for the webhook HTTPS server TLS key file.")
}