You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: letsencrypt.go
    path of file: ./repos/netbird/encryption
    
    the code of the file until where you have to start completion: package encryption

import (
	"os"
	"path/filepath"

	log "github.com/sirupsen/logrus"
	"golang.org/x/crypto/acme/autocert"
)

// CreateCertManager wraps common logic of generating Let's encrypt certificate.
func CreateCertManager(datadir string, letsencryptDomain string) (*autocert.Manager, error) {
	certDir := filepath.Join(datadir, "letsencrypt")

	if _, err := os.Stat(ce
    
func CreateCertManager(datadir string, letsencryptDomain string) (*autocert.Manager, error) {
	certDir := filepath.Join(datadir, "letsencrypt")

	if _, err := os.Stat(certDir); os.IsNotExist(err) {
		err = os.MkdirAll(certDir, 0755)
		if err != nil {
			return nil, err
		}
	}

	log.Infof("running with LetsEncrypt (%s). Cert will be stored in %s", letsencryptDomain, certDir)

	certManager := &autocert.Manager{
		Prompt:     autocert.AcceptTOS,
		Cache:      autocert.DirCache(certDir),
		HostPolicy: autocert.HostWhitelist(letsencryptDomain),
	}

	return certManager, nil
}