Get region from AWS SDK if NoIID = true

agent/config/config.go

@@ -192,8 +192,17 @@ func NewConfig(ec2client ec2.EC2MetadataClient) (*Config, error) {
 	config.Merge(userDataConfig(ec2client))
 
 	if config.AWSRegion == "" {
-		// Get it from metadata only if we need to (network io)
-		config.Merge(ec2MetadataConfig(ec2client))
+		if config.NoIID {
+			// get it from AWS SDK if we don't have instance identity document
+			awsRegion, err := ec2client.Region()
+			if err != nil {
+				errs = append(errs, err)
+			}
+			config.AWSRegion = awsRegion
+		} else {
+			// Get it from metadata only if we need to (network io)
+			config.Merge(ec2MetadataConfig(ec2client))
+		}
 	}
 
 	return config, config.mergeDefaultConfig(errs)

agent/config/config_test.go

@@ -67,6 +67,25 @@ func TestBrokenEC2MetadataEndpoint(t *testing.T) {
 	assert.Zero(t, config.APIEndpoint, "Endpoint env variable not set; endpoint should be blank")
 }
 
+func TestGetRegionWithNoIID(t *testing.T) {
+	defer setTestEnv("AWS_DEFAULT_REGION", "")()
+	ctrl := gomock.NewController(t)
+	mockEc2Metadata := mock_ec2.NewMockEC2MetadataClient(ctrl)
+
+	userDataResponse := `{ "ECSAgentConfiguration":{
+		"Cluster":"arn:aws:ecs:us-east-1:123456789012:cluster/my-cluster",
+		"APIEndpoint":"https://some-endpoint.com",
+		"NoIID":true
+	}}`
+	mockEc2Metadata.EXPECT().GetUserData().Return(userDataResponse, nil)
+	mockEc2Metadata.EXPECT().Region().Return("us-east-1", nil)
+
+	config, err := NewConfig(mockEc2Metadata)
+	assert.NoError(t, err)
+	assert.Equal(t, config.AWSRegion, "us-east-1", "Wrong region")
+	assert.Equal(t, config.APIEndpoint, "https://some-endpoint.com", "Endpoint env variable not set; endpoint should be blank")
+}
+
 func TestEnvironmentConfig(t *testing.T) {
 	defer setTestRegion()()
 	defer setTestEnv("ECS_CLUSTER", "myCluster")()

agent/ec2/blackhole_ec2_metadata_client.go

@@ -60,3 +60,7 @@ func (blackholeMetadataClient) GetDynamicData(path string) (string, error) {
 func (blackholeMetadataClient) GetUserData() (string, error) {
 	return "", errors.New("blackholed")
 }
+
+func (blackholeMetadataClient) Region() (string, error) {
+	return "", errors.New("blackholed")
+}

agent/ec2/ec2_metadata_client.go

@@ -55,6 +55,7 @@ type HttpClient interface {
 	GetDynamicData(string) (string, error)
 	GetInstanceIdentityDocument() (ec2metadata.EC2InstanceIdentityDocument, error)
 	GetUserData() (string, error)
+	Region() (string, error)
 }
 
 // EC2MetadataClient is the client used to get metadata from instance metadata service
@@ -68,6 +69,7 @@ type EC2MetadataClient interface {
 	PrimaryENIMAC() (string, error)
 	InstanceID() (string, error)
 	GetUserData() (string, error)
+	Region() (string, error)
 }
 
 type ec2MetadataClientImpl struct {
@@ -155,3 +157,8 @@ func (c *ec2MetadataClientImpl) InstanceID() (string, error) {
 func (c *ec2MetadataClientImpl) GetUserData() (string, error) {
 	return c.client.GetUserData()
 }
+
+// Region returns the region the instance is running in.
+func (c *ec2MetadataClientImpl) Region() (string, error) {
+	return c.client.Region()
+}