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main.go
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main.go
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package main
import (
"context"
"crypto/tls"
"fmt"
"log"
"net/http"
"os"
"os/signal"
"path/filepath"
"strings"
"syscall"
"time"
"github.com/fsnotify/fsnotify"
"github.com/kelseyhightower/envconfig"
"go.uber.org/zap"
"go.uber.org/zap/zapcore"
"github.com/newrelic/k8s-metadata-injection/src/server"
)
const (
appName = "new-relic-k8s-metadata-injection"
)
// specification contains the specs for this app.
type specification struct {
Port int `default:"8443"` // Webhook server port.
TLSCertFile string `default:"/etc/tls-key-cert-pair/tls.crt" envconfig:"tls_cert_file"` // File containing the x509 Certificate for HTTPS.
TLSKeyFile string `default:"/etc/tls-key-cert-pair/tls.key" envconfig:"tls_key_file"` // File containing the x509 private key for TLSCERTFILE.
ClusterName string `default:"cluster" split_words:"true"` // The name of the Kubernetes cluster.
Timeout time.Duration `default:"1s"` // Server timeout for the pod mutation.
}
func main() {
var s specification
err := envconfig.Process(strings.Replace(appName, "-", "_", -1), &s)
if err != nil {
log.Fatal(err.Error())
}
logger := setupLogger()
defer func() { _ = logger.Sync() }()
pair, err := tls.LoadX509KeyPair(s.TLSCertFile, s.TLSKeyFile)
if err != nil {
logger.Errorw("failed to load key pair", "err", err)
}
watcher, _ := fsnotify.NewWatcher()
defer func() { _ = watcher.Close() }()
// Watch the parent directory of the key/cert files so we can catch
// symlink updates of k8s secrets volumes and reload the certificates whenever they change.
watchDir, _ := filepath.Split(s.TLSCertFile)
if err := watcher.Add(watchDir); err != nil {
logger.Errorw("could not watch folder", "folder", watchDir, "err", err)
}
whsvr := &server.Webhook{
KeyFile: s.TLSKeyFile,
CertFile: s.TLSCertFile,
Cert: &pair,
ClusterName: s.ClusterName,
CertWatcher: watcher,
Server: &http.Server{
Addr: fmt.Sprintf(":%d", s.Port),
},
Logger: logger,
}
whsvr.Server.TLSConfig = &tls.Config{GetCertificate: whsvr.GetCert}
mux := http.NewServeMux()
mux.Handle("/mutate", withLoggingMiddleware(logger)(withTimeoutMiddleware(s.Timeout)(whsvr)))
whsvr.Server.Handler = mux
// The health check needs to be in another server because it cannot be under TLS.
readinessProbe := server.TLSReadyReadinessProbe(whsvr)
go func() {
logger.Info("starting the TLS readiness server")
if err := http.ListenAndServe(":8080", readinessProbe); err != nil {
logger.Errorw("failed to start TLS readiness server", "err", err)
}
}()
go func() {
logger.Info("starting the webhook server")
if err := whsvr.Server.ListenAndServeTLS("", ""); err != nil {
logger.Errorw("failed to start webhook server", "err", err)
}
}()
signalChan := make(chan os.Signal, 1)
signal.Notify(signalChan, syscall.SIGINT, syscall.SIGTERM)
var debounceTimer <-chan time.Time
for {
select {
case <-debounceTimer:
pair, err := tls.LoadX509KeyPair(whsvr.CertFile, whsvr.KeyFile)
if err != nil {
logger.Errorw("reload cert error", "err", err)
break
}
whsvr.Lock()
whsvr.Cert = &pair
whsvr.Unlock()
logger.Info("cert/key pair reloaded!")
case event := <-whsvr.CertWatcher.Events:
if event.Op&fsnotify.Write == fsnotify.Write || event.Op&fsnotify.Create == fsnotify.Create {
debounceTimer = time.After(500 * time.Millisecond)
}
case <-signalChan:
logger.Info("got OS shutdown signal, shutting down webhook server gracefully...")
_ = watcher.Close()
_ = whsvr.Server.Shutdown(context.Background())
return
}
}
}
func withTimeoutMiddleware(timeout time.Duration) func(next http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
http.TimeoutHandler(next, timeout, "server timeout").ServeHTTP(w, r)
})
}
}
func withLoggingMiddleware(logger *zap.SugaredLogger) func(next http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
fn := func(w http.ResponseWriter, r *http.Request) {
scheme := "http"
if r.TLS != nil {
scheme = "https"
}
logger.Infof("%s %s://%s%s %s\" from %s", r.Method, scheme, r.Host, r.RequestURI, r.Proto, r.RemoteAddr)
next.ServeHTTP(w, r)
}
return http.HandlerFunc(fn)
}
}
func setupLogger() *zap.SugaredLogger {
config := zap.NewProductionConfig()
config.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder // We want human readable timestamps.
zapLogger, err := config.Build()
if err != nil {
log.Fatalf("can't initialize zap logger: %v", err)
}
return zapLogger.Sugar()
}