Read OpenStack creds from standard paths

OpenStack creds cold be in 3 different paths (etc, home config and
current dir). Instead of re-implementing the logic to find and read the
clouds.yaml file, we should use gophercloud which is the standard
go library for OpenStack.

Note that deployments on OpenStack are currently broken unless there's
a clouds.yaml under /etc/openstack.

Fixes openshift#550

pkg/asset/manifests/tectonic.go

@@ -1,16 +1,14 @@
 package manifests
 
 import (
-	"bufio"
 	"encoding/base64"
-	"io/ioutil"
-	"os"
 	"path/filepath"
 
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/ghodss/yaml"
 	"github.com/pkg/errors"
 
+	"github.com/gophercloud/utils/openstack/clientconfig"
 	"github.com/openshift/installer/pkg/asset"
 	"github.com/openshift/installer/pkg/asset/installconfig"
 	"github.com/openshift/installer/pkg/asset/machines"
@@ -20,7 +18,6 @@ import (
 
 const (
 	tectonicManifestDir = "tectonic"
-	openStackCredsFile  = "/etc/openstack/clouds.yaml"
 )
 
 var (
@@ -80,10 +77,17 @@ func (t *Tectonic) Generate(dependencies asset.Parents) error {
 			},
 		}
 	case "openstack":
-		credsEncoded, err := credsFileEncode(openStackCredsFile)
+		clouds, err := clientconfig.LoadCloudsYAML()
 		if err != nil {
 			return err
 		}
+
+		marshalled, err := yaml.Marshal(clouds)
+		if err != nil {
+			return err
+		}
+
+		credsEncoded := base64.StdEncoding.EncodeToString(marshalled)
 		cloudCreds = cloudCredsSecretData{
 			OpenStack: &OpenStackCredsSecretData{
 				Base64encodeCloudCreds: credsEncoded,
@@ -176,14 +180,3 @@ func (t *Tectonic) Load(f asset.FileFetcher) (bool, error) {
 	t.FileList, t.TectonicConfig = fileList, tectonicConfig
 	return true, nil
 }
-
-// credsFileEncode returns contents of a file as base64 encoded string
-func credsFileEncode(credsFile string) (string, error) {
-	f, _ := os.Open(credsFile)
-	reader := bufio.NewReader(f)
-	credsData, err := ioutil.ReadAll(reader)
-	if err != nil {
-		return "", err
-	}
-	return base64.StdEncoding.EncodeToString(credsData), nil
-}