Added code to save the managed instance's region to the stored cred profile

agent/managedInstances/rolecreds/managedInstances_role_provider_test.go

@@ -21,6 +21,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/aws/amazon-ssm-agent/agent/fileutil"
+	"github.com/aws/amazon-ssm-agent/agent/managedInstances/sharedCredentials"
 	"github.com/aws/aws-sdk-go/service/ssm"
 	"github.com/stretchr/testify/assert"
 )
@@ -29,8 +31,17 @@ var (
 	accessKeyID     = "accessKeyID"
 	secretAccessKey = "secretAccessKey"
 	sessionToken    = "sessionToken"
+	region          = "us-east-1"
 )
 
+func cleanupCredFile() {
+	if credPath, err := sharedCredentials.Filename(); err == nil {
+		if credPath != "" && fileutil.Exists(credPath) {
+			fileutil.DeleteFile(credPath)
+		}
+	}
+}
+
 func TestRetrieve_ShouldReturnValidToken(t *testing.T) {
 	updateKeyPair := false
 	tokenExpirationDate := time.Now().Add(1 * time.Hour)
@@ -51,6 +62,8 @@ func TestRetrieve_ShouldReturnValidToken(t *testing.T) {
 	assert.Equal(t, accessKeyID, cred.AccessKeyID)
 	assert.Equal(t, secretAccessKey, cred.SecretAccessKey)
 	assert.Equal(t, sessionToken, cred.SessionToken)
+
+	cleanupCredFile()
 }
 
 func TestRetrieve_ShouldUpdateKeyPair(t *testing.T) {
@@ -60,6 +73,7 @@ func TestRetrieve_ShouldUpdateKeyPair(t *testing.T) {
 		publicKey:  "publicKey",
 		privateKey: "privateKey",
 		keyType:    "Rsa",
+		region:     "us-east-1",
 	}
 	client := &RsaSignedServiceStub{
 		roleResponse: ssm.RequestManagedInstanceRoleTokenOutput{
@@ -76,6 +90,7 @@ func TestRetrieve_ShouldUpdateKeyPair(t *testing.T) {
 	_, err := testProvider.Retrieve()
 	assert.NoError(t, err)
 	assert.True(t, client.updateCalled)
+	cleanupCredFile()
 }
 
 func TestRetrieve_ShouldFailOnError(t *testing.T) {

agent/managedInstances/sharedCredentials/shared_Credentials.go

@@ -20,6 +20,7 @@ import (
 	"path/filepath"
 
 	"github.com/aws/amazon-ssm-agent/agent/fileutil"
+	"github.com/aws/amazon-ssm-agent/agent/managedInstances/registration"
 	"github.com/aws/aws-sdk-go/aws/awserr"
 	"github.com/go-ini/ini"
 )
@@ -29,12 +30,12 @@ const (
 	awsAccessKeyID     = "aws_access_key_id"
 	awsSecretAccessKey = "aws_secret_access_key"
 	awsSessionToken    = "aws_session_token"
+	awsRegion          = "region"
 )
 
-// filename returns the filename to use to read AWS shared credentials.
-//
+// Filename returns the filename to use to read AWS shared credentials.
 // Will return an error if the user's home directory path cannot be found.
-func filename() (string, error) {
+func Filename() (string, error) {
 	if credPath := os.Getenv("AWS_SHARED_CREDENTIALS_FILE"); credPath != "" {
 		return credPath, nil
 	}
@@ -68,7 +69,7 @@ func Store(accessKeyID, secretAccessKey, sessionToken, profile string) error {
 		profile = defaultProfile
 	}
 
-	credPath, err := filename()
+	credPath, err := Filename()
 	if err != nil {
 		return err
 	}
@@ -98,6 +99,18 @@ func Store(accessKeyID, secretAccessKey, sessionToken, profile string) error {
 
 	iniProfile.Key(awsSessionToken).SetValue(sessionToken)
 
+	// Save the instance's region to the profile so that the FallbackRegionFactory can find it.
+	// Scripts that use the .NET Cmdlets and aws command line tools will automatically detect
+	// the AWS Region from the EC2 instance profile, however, this is not the case for on-prem
+	// servers, since they don't have the EC2 Metadata service. By adding the Region to the
+	// shared credentials file, the SDK will be able to discover the region automatically.
+	// This will ensure that scripts that run on on-prem servers will run the same way as
+	// they would on EC2 instances, without any modification.
+	region := registration.Region()
+	if region != "" {
+		iniProfile.Key(awsRegion).SetValue(region)
+	}
+
 	err = config.SaveTo(credPath)
 	if err != nil {
 		return awserr.New("SharedCredentialsStore", "failed to save profile", err)

agent/managedInstances/sharedCredentials/shared_credentials_integ_test.go

@@ -30,6 +30,7 @@ const (
 	accessKey       = "DummyAccessKey"
 	accessSecretKey = "DummyAccessSecretKey"
 	token           = "DummyToken"
+	region          = "us-east-1"
 	profile         = "DummyProfile"
 	testFilePath    = "example.ini"
 )

agent/s3util/s3util.go

@@ -116,8 +116,8 @@ func (u *AmazonS3Util) S3Upload(log log.T, bucketName string, objectKey string,
 func GetBucketRegion(log log.T, bucketName string, httpProvider HttpProvider) (region string) {
 	instanceRegion, err := getRegion()
 	if err != nil {
-		log.Error("Cannot get the current instance region information")
-		return instanceRegion // Default
+		log.Error(fmt.Errorf("Cannot get the current instance region information: %v", err))
+		return "us-east-1" // Default
 	}
 	log.Infof("Instance region is %v", instanceRegion)