TLS parameters support for OpenStack

TLS parameters can be passed through the following environment
variables:
* OPENSTACK_CA_FILE - CA file path
* OPENSTACK_CERT_FILE - cert file path
* OPENSTACK_KEY_FILE - key file path. Either both or none of cert/key
  must be specified
* OPENSTACK_TLS_SERVER_NAME - (optional) expected CN of the server
  certificate if differs from domain in the URL
* OPENSTACK_TLS_INSECURE - if set to yes|true|1 disables validation of
  the server certificate

Code that loads tls.Config from environment variables was extracted
into dedicated package so that it could be reused by different providers

pkg/tlsutils/tlsconfig.go

@@ -0,0 +1,85 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package tlsutils
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+)
+
+// CreateTLSConfig creates tls.Config instance from TLS parameters passed in environment variables with the given prefix
+func CreateTLSConfig(prefix string) (*tls.Config, error) {
+	caFile := os.Getenv(fmt.Sprintf("%s_CA_FILE", prefix))
+	certFile := os.Getenv(fmt.Sprintf("%s_CERT_FILE", prefix))
+	keyFile := os.Getenv(fmt.Sprintf("%s_KEY_FILE", prefix))
+	serverName := os.Getenv(fmt.Sprintf("%s_TLS_SERVER_NAME", prefix))
+	isInsecureStr := strings.ToLower(os.Getenv(fmt.Sprintf("%s_TLS_INSECURE", prefix)))
+	isInsecure := isInsecureStr == "true" || isInsecureStr == "yes" || isInsecureStr == "1"
+	tlsConfig, err := newTLSConfig(certFile, keyFile, caFile, serverName, isInsecure)
+	if err != nil {
+		return nil, err
+	}
+	return tlsConfig, nil
+}
+
+func newTLSConfig(certPath, keyPath, caPath, serverName string, insecure bool) (*tls.Config, error) {
+	if certPath != "" && keyPath == "" || certPath == "" && keyPath != "" {
+		return nil, errors.New("either both cert and key or none must be provided")
+	}
+	var certificates []tls.Certificate
+	if certPath != "" {
+		cert, err := tls.LoadX509KeyPair(certPath, keyPath)
+		if err != nil {
+			return nil, fmt.Errorf("could not load TLS cert: %s", err)
+		}
+		certificates = append(certificates, cert)
+	}
+	roots, err := loadRoots(caPath)
+	if err != nil {
+		return nil, err
+	}
+
+	return &tls.Config{
+		Certificates:       certificates,
+		RootCAs:            roots,
+		InsecureSkipVerify: insecure,
+		ServerName:         serverName,
+	}, nil
+}
+
+// loads CA cert
+func loadRoots(caPath string) (*x509.CertPool, error) {
+	if caPath == "" {
+		return nil, nil
+	}
+
+	roots := x509.NewCertPool()
+	pem, err := ioutil.ReadFile(caPath)
+	if err != nil {
+		return nil, fmt.Errorf("error reading %s: %s", caPath, err)
+	}
+	ok := roots.AppendCertsFromPEM(pem)
+	if !ok {
+		return nil, fmt.Errorf("could not read root certs: %s", err)
+	}
+	return roots, nil
+}

provider/designate.go

@@ -18,8 +18,11 @@ package provider
 
 import (
 	"fmt"
+	"net"
+	"net/http"
 	"os"
 	"strings"
+	"time"
 
 	log "github.com/Sirupsen/logrus"
 	"github.com/gophercloud/gophercloud"
@@ -29,6 +32,7 @@ import (
 	"github.com/gophercloud/gophercloud/pagination"
 
 	"github.com/kubernetes-incubator/external-dns/endpoint"
+	"github.com/kubernetes-incubator/external-dns/pkg/tlsutils"
 	"github.com/kubernetes-incubator/external-dns/plan"
 )
 
@@ -132,6 +136,25 @@ func createDesignateServiceClient() (*gophercloud.ServiceClient, error) {
 	if err != nil {
 		return nil, err
 	}
+
+	tlsConfig, err := tlsutils.CreateTLSConfig("OPENSTACK")
+	if err != nil {
+		return nil, err
+	}
+
+	transport := &http.Transport{
+		Proxy: http.ProxyFromEnvironment,
+		DialContext: (&net.Dialer{
+			Timeout:   30 * time.Second,
+			KeepAlive: 30 * time.Second,
+		}).DialContext,
+		MaxIdleConns:          100,
+		IdleConnTimeout:       90 * time.Second,
+		TLSHandshakeTimeout:   10 * time.Second,
+		ExpectContinueTimeout: 1 * time.Second,
+		TLSClientConfig:       tlsConfig,
+	}
+	client.ProviderClient.HTTPClient.Transport = transport
 	log.Infof("Found OpenStack Designate service at %s", client.Endpoint)
 	return client, nil
 }