Use credentials file passed through config

Add a new supported key to the config which allows the path to a
credentials file to be passed through to the ObjectStore and
VolumeSnapshotter plugins. If that key is set in the config, use that
file as the credentials file for the AWS client.

This can be tested by adding a new key to the `cloud-credentials` secret
and adding the key value pair `credentialsFile=/credentials/<key_name>`.

Signed-off-by: Bridget McErlean <bmcerlean@vmware.com>

velero-plugin-for-aws/object_store.go

@@ -46,6 +46,7 @@ const (
 	s3ForcePathStyleKey      = "s3ForcePathStyle"
 	bucketKey                = "bucket"
 	signatureVersionKey      = "signatureVersion"
+	credentialsFileKey       = "credentialsFile"
 	credentialProfileKey     = "profile"
 	serverSideEncryptionKey  = "serverSideEncryption"
 	insecureSkipTLSVerifyKey = "insecureSkipTLSVerify"
@@ -90,6 +91,7 @@ func (o *ObjectStore) Init(config map[string]string) error {
 		kmsKeyIDKey,
 		s3ForcePathStyleKey,
 		signatureVersionKey,
+		credentialsFileKey,
 		credentialProfileKey,
 		serverSideEncryptionKey,
 		insecureSkipTLSVerifyKey,
@@ -105,6 +107,7 @@ func (o *ObjectStore) Init(config map[string]string) error {
 		s3ForcePathStyleVal      = config[s3ForcePathStyleKey]
 		signatureVersion         = config[signatureVersionKey]
 		credentialProfile        = config[credentialProfileKey]
+		credentialsFile          = config[credentialsFileKey]
 		serverSideEncryption     = config[serverSideEncryptionKey]
 		insecureSkipTLSVerifyVal = config[insecureSkipTLSVerifyKey]
 
@@ -170,6 +173,9 @@ func (o *ObjectStore) Init(config map[string]string) error {
 	if len(caCert) > 0 {
 		sessionOptions.CustomCABundle = strings.NewReader(caCert)
 	}
+	if credentialsFile != "" {
+		sessionOptions.SharedConfigFiles = []string{credentialsFile}
+	}
 	serverSession, err := getSession(sessionOptions)
 	if err != nil {
 		return err
@@ -196,6 +202,9 @@ func (o *ObjectStore) Init(config map[string]string) error {
 		if len(caCert) > 0 {
 			sessionOptions.CustomCABundle = strings.NewReader(caCert)
 		}
+		if credentialsFile != "" {
+			sessionOptions.SharedConfigFiles = []string{credentialsFile}
+		}
 		publicSession, err := getSession(sessionOptions)
 		if err != nil {
 			return err

velero-plugin-for-aws/volume_snapshotter.go

@@ -66,19 +66,23 @@ func newVolumeSnapshotter(logger logrus.FieldLogger) *VolumeSnapshotter {
 }
 
 func (b *VolumeSnapshotter) Init(config map[string]string) error {
-	if err := veleroplugin.ValidateVolumeSnapshotterConfigKeys(config, regionKey, credentialProfileKey); err != nil {
+	if err := veleroplugin.ValidateVolumeSnapshotterConfigKeys(config, regionKey, credentialsFileKey, credentialProfileKey); err != nil {
 		return err
 	}
 
 	region := config[regionKey]
 	credentialProfile := config[credentialProfileKey]
+	credentialsFile := config[credentialsFileKey]
 	if region == "" {
 		return errors.Errorf("missing %s in aws configuration", regionKey)
 	}
 
 	awsConfig := aws.NewConfig().WithRegion(region)
 
 	sessionOptions := session.Options{Config: *awsConfig, Profile: credentialProfile}
+	if credentialsFile != "" {
+		sessionOptions.SharedConfigFiles = []string{credentialsFile}
+	}
 	sess, err := getSession(sessionOptions)
 	if err != nil {
 		return err