google/internal: Add AWS Session Token to Metadata Requests

AWS released a new instance metadata service (IMDSv2). IMDSv2 brought a requirement that a session token header is now required on every call to metadata endpoint.
Modify the AWS credential retrieval flow to fetch the session token and send it along with the calls to metadata endpoints

Change-Id: I539912ab38f5e591658b29a1e7a99d2b828a1128
GitHub-Last-Rev: 29e1f4aad1
GitHub-Pull-Request: golang/oauth2#554
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/390794
Reviewed-by: Cody Oss <codyoss@google.com>
Trust: Cody Oss <codyoss@google.com>
Run-TryBot: Cody Oss <codyoss@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Leo Siracusa <leosiracusa@google.com>
Trust: Tyler Bui-Palsulich <tbp@google.com>

google/internal/externalaccount/aws.go

@@ -52,6 +52,13 @@ const (
 	// The AWS authorization header name for the security session token if available.
 	awsSecurityTokenHeader = "x-amz-security-token"
 
+	// The name of the header containing the session token for metadata endpoint calls
+	awsIMDSv2SessionTokenHeader = "X-aws-ec2-metadata-token"
+
+	awsIMDSv2SessionTtlHeader = "X-aws-ec2-metadata-token-ttl-seconds"
+
+	awsIMDSv2SessionTtl = "300"
+
 	// The AWS authorization header name for the auto-generated date.
 	awsDateHeader = "x-amz-date"
 
@@ -241,6 +248,7 @@ type awsCredentialSource struct {
 	RegionURL                   string
 	RegionalCredVerificationURL string
 	CredVerificationURL         string
+	IMDSv2SessionTokenURL       string
 	TargetResource              string
 	requestSigner               *awsRequestSigner
 	region                      string
@@ -268,12 +276,22 @@ func (cs awsCredentialSource) doRequest(req *http.Request) (*http.Response, erro
 
 func (cs awsCredentialSource) subjectToken() (string, error) {
 	if cs.requestSigner == nil {
-		awsSecurityCredentials, err := cs.getSecurityCredentials()
+		awsSessionToken, err := cs.getAWSSessionToken()
 		if err != nil {
 			return "", err
 		}
 
-		if cs.region, err = cs.getRegion(); err != nil {
+		headers := make(map[string]string)
+		if awsSessionToken != "" {
+			headers[awsIMDSv2SessionTokenHeader] = awsSessionToken
+		}
+
+		awsSecurityCredentials, err := cs.getSecurityCredentials(headers)
+		if err != nil {
+			return "", err
+		}
+
+		if cs.region, err = cs.getRegion(headers); err != nil {
 			return "", err
 		}
 
@@ -340,7 +358,37 @@ func (cs awsCredentialSource) subjectToken() (string, error) {
 	return url.QueryEscape(string(result)), nil
 }
 
-func (cs *awsCredentialSource) getRegion() (string, error) {
+func (cs *awsCredentialSource) getAWSSessionToken() (string, error) {
+	if cs.IMDSv2SessionTokenURL == "" {
+		return "", nil
+	}
+
+	req, err := http.NewRequest("PUT", cs.IMDSv2SessionTokenURL, nil)
+	if err != nil {
+		return "", err
+	}
+
+	req.Header.Add(awsIMDSv2SessionTtlHeader, awsIMDSv2SessionTtl)
+
+	resp, err := cs.doRequest(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	respBody, err := ioutil.ReadAll(io.LimitReader(resp.Body, 1<<20))
+	if err != nil {
+		return "", err
+	}
+
+	if resp.StatusCode != 200 {
+		return "", fmt.Errorf("oauth2/google: unable to retrieve AWS session token - %s", string(respBody))
+	}
+
+	return string(respBody), nil
+}
+
+func (cs *awsCredentialSource) getRegion(headers map[string]string) (string, error) {
 	if envAwsRegion := getenv("AWS_REGION"); envAwsRegion != "" {
 		return envAwsRegion, nil
 	}
@@ -357,6 +405,10 @@ func (cs *awsCredentialSource) getRegion() (string, error) {
 		return "", err
 	}
 
+	for name, value := range headers {
+		req.Header.Add(name, value)
+	}
+
 	resp, err := cs.doRequest(req)
 	if err != nil {
 		return "", err
@@ -381,7 +433,7 @@ func (cs *awsCredentialSource) getRegion() (string, error) {
 	return string(respBody[:respBodyEnd]), nil
 }
 
-func (cs *awsCredentialSource) getSecurityCredentials() (result awsSecurityCredentials, err error) {
+func (cs *awsCredentialSource) getSecurityCredentials(headers map[string]string) (result awsSecurityCredentials, err error) {
 	if accessKeyID := getenv("AWS_ACCESS_KEY_ID"); accessKeyID != "" {
 		if secretAccessKey := getenv("AWS_SECRET_ACCESS_KEY"); secretAccessKey != "" {
 			return awsSecurityCredentials{
@@ -392,12 +444,12 @@ func (cs *awsCredentialSource) getSecurityCredentials() (result awsSecurityCrede
 		}
 	}
 
-	roleName, err := cs.getMetadataRoleName()
+	roleName, err := cs.getMetadataRoleName(headers)
 	if err != nil {
 		return
 	}
 
-	credentials, err := cs.getMetadataSecurityCredentials(roleName)
+	credentials, err := cs.getMetadataSecurityCredentials(roleName, headers)
 	if err != nil {
 		return
 	}
@@ -413,7 +465,7 @@ func (cs *awsCredentialSource) getSecurityCredentials() (result awsSecurityCrede
 	return credentials, nil
 }
 
-func (cs *awsCredentialSource) getMetadataSecurityCredentials(roleName string) (awsSecurityCredentials, error) {
+func (cs *awsCredentialSource) getMetadataSecurityCredentials(roleName string, headers map[string]string) (awsSecurityCredentials, error) {
 	var result awsSecurityCredentials
 
 	req, err := http.NewRequest("GET", fmt.Sprintf("%s/%s", cs.CredVerificationURL, roleName), nil)
@@ -422,6 +474,10 @@ func (cs *awsCredentialSource) getMetadataSecurityCredentials(roleName string) (
 	}
 	req.Header.Add("Content-Type", "application/json")
 
+	for name, value := range headers {
+		req.Header.Add(name, value)
+	}
+
 	resp, err := cs.doRequest(req)
 	if err != nil {
 		return result, err
@@ -441,7 +497,7 @@ func (cs *awsCredentialSource) getMetadataSecurityCredentials(roleName string) (
 	return result, err
 }
 
-func (cs *awsCredentialSource) getMetadataRoleName() (string, error) {
+func (cs *awsCredentialSource) getMetadataRoleName(headers map[string]string) (string, error) {
 	if cs.CredVerificationURL == "" {
 		return "", errors.New("oauth2/google: unable to determine the AWS metadata server security credentials endpoint")
 	}
@@ -451,6 +507,10 @@ func (cs *awsCredentialSource) getMetadataRoleName() (string, error) {
 		return "", err
 	}
 
+	for name, value := range headers {
+		req.Header.Add(name, value)
+	}
+
 	resp, err := cs.doRequest(req)
 	if err != nil {
 		return "", err

google/internal/externalaccount/aws_test.go

@@ -20,6 +20,8 @@ import (
 var defaultTime = time.Date(2011, 9, 9, 23, 36, 0, 0, time.UTC)
 var secondDefaultTime = time.Date(2020, 8, 11, 6, 55, 22, 0, time.UTC)
 
+type validateHeaders func(r *http.Request)
+
 func setTime(testTime time.Time) func() time.Time {
 	return func() time.Time {
 		return testTime
@@ -82,7 +84,7 @@ func testRequestSigner(t *testing.T, rs *awsRequestSigner, input, expectedOutput
 	}
 }
 
-func TestAwsV4Signature_GetRequest(t *testing.T) {
+func TestAWSv4Signature_GetRequest(t *testing.T) {
 	input, _ := http.NewRequest("GET", "https://host.foo.com", nil)
 	setDefaultTime(input)
 
@@ -100,7 +102,7 @@ func TestAwsV4Signature_GetRequest(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_GetRequestWithRelativePath(t *testing.T) {
+func TestAWSv4Signature_GetRequestWithRelativePath(t *testing.T) {
 	input, _ := http.NewRequest("GET", "https://host.foo.com/foo/bar/../..", nil)
 	setDefaultTime(input)
 
@@ -118,7 +120,7 @@ func TestAwsV4Signature_GetRequestWithRelativePath(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_GetRequestWithDotPath(t *testing.T) {
+func TestAWSv4Signature_GetRequestWithDotPath(t *testing.T) {
 	input, _ := http.NewRequest("GET", "https://host.foo.com/./", nil)
 	setDefaultTime(input)
 
@@ -136,7 +138,7 @@ func TestAwsV4Signature_GetRequestWithDotPath(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_GetRequestWithPointlessDotPath(t *testing.T) {
+func TestAWSv4Signature_GetRequestWithPointlessDotPath(t *testing.T) {
 	input, _ := http.NewRequest("GET", "https://host.foo.com/./foo", nil)
 	setDefaultTime(input)
 
@@ -154,7 +156,7 @@ func TestAwsV4Signature_GetRequestWithPointlessDotPath(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_GetRequestWithUtf8Path(t *testing.T) {
+func TestAWSv4Signature_GetRequestWithUtf8Path(t *testing.T) {
 	input, _ := http.NewRequest("GET", "https://host.foo.com/%E1%88%B4", nil)
 	setDefaultTime(input)
 
@@ -172,7 +174,7 @@ func TestAwsV4Signature_GetRequestWithUtf8Path(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_GetRequestWithDuplicateQuery(t *testing.T) {
+func TestAWSv4Signature_GetRequestWithDuplicateQuery(t *testing.T) {
 	input, _ := http.NewRequest("GET", "https://host.foo.com/?foo=Zoo&foo=aha", nil)
 	setDefaultTime(input)
 
@@ -190,7 +192,7 @@ func TestAwsV4Signature_GetRequestWithDuplicateQuery(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_GetRequestWithMisorderedQuery(t *testing.T) {
+func TestAWSv4Signature_GetRequestWithMisorderedQuery(t *testing.T) {
 	input, _ := http.NewRequest("GET", "https://host.foo.com/?foo=b&foo=a", nil)
 	setDefaultTime(input)
 
@@ -208,7 +210,7 @@ func TestAwsV4Signature_GetRequestWithMisorderedQuery(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_GetRequestWithUtf8Query(t *testing.T) {
+func TestAWSv4Signature_GetRequestWithUtf8Query(t *testing.T) {
 	input, _ := http.NewRequest("GET", "https://host.foo.com/?ሴ=bar", nil)
 	setDefaultTime(input)
 
@@ -226,7 +228,7 @@ func TestAwsV4Signature_GetRequestWithUtf8Query(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_PostRequest(t *testing.T) {
+func TestAWSv4Signature_PostRequest(t *testing.T) {
 	input, _ := http.NewRequest("POST", "https://host.foo.com/", nil)
 	setDefaultTime(input)
 	input.Header.Add("ZOO", "zoobar")
@@ -246,7 +248,7 @@ func TestAwsV4Signature_PostRequest(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_PostRequestWithCapitalizedHeaderValue(t *testing.T) {
+func TestAWSv4Signature_PostRequestWithCapitalizedHeaderValue(t *testing.T) {
 	input, _ := http.NewRequest("POST", "https://host.foo.com/", nil)
 	setDefaultTime(input)
 	input.Header.Add("zoo", "ZOOBAR")
@@ -266,7 +268,7 @@ func TestAwsV4Signature_PostRequestWithCapitalizedHeaderValue(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_PostRequestPhfft(t *testing.T) {
+func TestAWSv4Signature_PostRequestPhfft(t *testing.T) {
 	input, _ := http.NewRequest("POST", "https://host.foo.com/", nil)
 	setDefaultTime(input)
 	input.Header.Add("p", "phfft")
@@ -286,7 +288,7 @@ func TestAwsV4Signature_PostRequestPhfft(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_PostRequestWithBody(t *testing.T) {
+func TestAWSv4Signature_PostRequestWithBody(t *testing.T) {
 	input, _ := http.NewRequest("POST", "https://host.foo.com/", strings.NewReader("foo=bar"))
 	setDefaultTime(input)
 	input.Header.Add("Content-Type", "application/x-www-form-urlencoded")
@@ -306,7 +308,7 @@ func TestAwsV4Signature_PostRequestWithBody(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_PostRequestWithQueryString(t *testing.T) {
+func TestAWSv4Signature_PostRequestWithQueryString(t *testing.T) {
 	input, _ := http.NewRequest("POST", "https://host.foo.com/?foo=bar", nil)
 	setDefaultTime(input)
 
@@ -324,7 +326,7 @@ func TestAwsV4Signature_PostRequestWithQueryString(t *testing.T) {
 	testRequestSigner(t, defaultRequestSigner, input, output)
 }
 
-func TestAwsV4Signature_GetRequestWithSecurityToken(t *testing.T) {
+func TestAWSv4Signature_GetRequestWithSecurityToken(t *testing.T) {
 	input, _ := http.NewRequest("GET", "https://ec2.us-east-2.amazonaws.com?Action=DescribeRegions&Version=2013-10-15", nil)
 
 	output, _ := http.NewRequest("GET", "https://ec2.us-east-2.amazonaws.com?Action=DescribeRegions&Version=2013-10-15", nil)
@@ -342,7 +344,7 @@ func TestAwsV4Signature_GetRequestWithSecurityToken(t *testing.T) {
 	testRequestSigner(t, requestSignerWithToken, input, output)
 }
 
-func TestAwsV4Signature_PostRequestWithSecurityToken(t *testing.T) {
+func TestAWSv4Signature_PostRequestWithSecurityToken(t *testing.T) {
 	input, _ := http.NewRequest("POST", "https://sts.us-east-2.amazonaws.com?Action=GetCallerIdentity&Version=2011-06-15", nil)
 
 	output, _ := http.NewRequest("POST", "https://sts.us-east-2.amazonaws.com?Action=GetCallerIdentity&Version=2011-06-15", nil)
@@ -360,7 +362,7 @@ func TestAwsV4Signature_PostRequestWithSecurityToken(t *testing.T) {
 	testRequestSigner(t, requestSignerWithToken, input, output)
 }
 
-func TestAwsV4Signature_PostRequestWithSecurityTokenAndAdditionalHeaders(t *testing.T) {
+func TestAWSv4Signature_PostRequestWithSecurityTokenAndAdditionalHeaders(t *testing.T) {
 	requestParams := "{\"KeySchema\":[{\"KeyType\":\"HASH\",\"AttributeName\":\"Id\"}],\"TableName\":\"TestTable\",\"AttributeDefinitions\":[{\"AttributeName\":\"Id\",\"AttributeType\":\"S\"}],\"ProvisionedThroughput\":{\"WriteCapacityUnits\":5,\"ReadCapacityUnits\":5}}"
 	input, _ := http.NewRequest("POST", "https://dynamodb.us-east-2.amazonaws.com/", strings.NewReader(requestParams))
 	input.Header.Add("Content-Type", "application/x-amz-json-1.0")
@@ -383,7 +385,7 @@ func TestAwsV4Signature_PostRequestWithSecurityTokenAndAdditionalHeaders(t *test
 	testRequestSigner(t, requestSignerWithToken, input, output)
 }
 
-func TestAwsV4Signature_PostRequestWithAmzDateButNoSecurityToken(t *testing.T) {
+func TestAWSv4Signature_PostRequestWithAmzDateButNoSecurityToken(t *testing.T) {
 	var requestSigner = &awsRequestSigner{
 		RegionName: "us-east-2",
 		AwsSecurityCredentials: awsSecurityCredentials{
@@ -413,30 +415,40 @@ type testAwsServer struct {
 	securityCredentialURL       string
 	regionURL                   string
 	regionalCredVerificationURL string
+	imdsv2SessionTokenUrl       string
 
 	Credentials map[string]string
 
-	WriteRolename            func(http.ResponseWriter)
+	WriteRolename            func(http.ResponseWriter, *http.Request)
-	WriteSecurityCredentials func(http.ResponseWriter)
+	WriteSecurityCredentials func(http.ResponseWriter, *http.Request)
-	WriteRegion              func(http.ResponseWriter)
+	WriteRegion              func(http.ResponseWriter, *http.Request)
+	WriteIMDSv2SessionToken  func(http.ResponseWriter, *http.Request)
 }
 
-func createAwsTestServer(url, regionURL, regionalCredVerificationURL, rolename, region string, credentials map[string]string) *testAwsServer {
+func createAwsTestServer(url, regionURL, regionalCredVerificationURL, imdsv2SessionTokenUrl string, rolename, region string, credentials map[string]string, imdsv2SessionToken string, validateHeaders validateHeaders) *testAwsServer {
 	server := &testAwsServer{
 		url:                         url,
 		securityCredentialURL:       fmt.Sprintf("%s/%s", url, rolename),
 		regionURL:                   regionURL,
 		regionalCredVerificationURL: regionalCredVerificationURL,
+		imdsv2SessionTokenUrl:       imdsv2SessionTokenUrl,
 		Credentials:                 credentials,
-		WriteRolename: func(w http.ResponseWriter) {
+		WriteRolename: func(w http.ResponseWriter, r *http.Request) {
+			validateHeaders(r)
 			w.Write([]byte(rolename))
 		},
-		WriteRegion: func(w http.ResponseWriter) {
+		WriteRegion: func(w http.ResponseWriter, r *http.Request) {
+			validateHeaders(r)
 			w.Write([]byte(region))
 		},
+		WriteIMDSv2SessionToken: func(w http.ResponseWriter, r *http.Request) {
+			validateHeaders(r)
+			w.Write([]byte(imdsv2SessionToken))
+		},
 	}
 
-	server.WriteSecurityCredentials = func(w http.ResponseWriter) {
+	server.WriteSecurityCredentials = func(w http.ResponseWriter, r *http.Request) {
+		validateHeaders(r)
 		jsonCredentials, _ := json.Marshal(server.Credentials)
 		w.Write(jsonCredentials)
 	}
@@ -449,6 +461,7 @@ func createDefaultAwsTestServer() *testAwsServer {
 		"/latest/meta-data/iam/security-credentials",
 		"/latest/meta-data/placement/availability-zone",
 		"https://sts.{region}.amazonaws.com?Action=GetCallerIdentity&Version=2011-06-15",
+		"",
 		"gcp-aws-role",
 		"us-east-2b",
 		map[string]string{
@@ -456,31 +469,38 @@ func createDefaultAwsTestServer() *testAwsServer {
 			"AccessKeyId":     accessKeyID,
 			"Token":           securityToken,
 		},
+		"",
+		noHeaderValidation,
 	)
 }
 
 func (server *testAwsServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	switch p := r.URL.Path; p {
 	case server.url:
-		server.WriteRolename(w)
+		server.WriteRolename(w, r)
 	case server.securityCredentialURL:
-		server.WriteSecurityCredentials(w)
+		server.WriteSecurityCredentials(w, r)
 	case server.regionURL:
-		server.WriteRegion(w)
+		server.WriteRegion(w, r)
+	case server.imdsv2SessionTokenUrl:
+		server.WriteIMDSv2SessionToken(w, r)
 	}
 }
 
-func notFound(w http.ResponseWriter) {
+func notFound(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(404)
 	w.Write([]byte("Not Found"))
 }
 
+func noHeaderValidation(r *http.Request) {}
+
 func (server *testAwsServer) getCredentialSource(url string) CredentialSource {
 	return CredentialSource{
 		EnvironmentID:               "aws1",
 		URL:                         url + server.url,
 		RegionURL:                   url + server.regionURL,
 		RegionalCredVerificationURL: server.regionalCredVerificationURL,
+		IMDSv2SessionTokenURL:       url + server.imdsv2SessionTokenUrl,
 	}
 }
 
@@ -530,7 +550,7 @@ func getExpectedSubjectToken(url, region, accessKeyID, secretAccessKey, security
 	return neturl.QueryEscape(string(str))
 }
 
-func TestAwsCredential_BasicRequest(t *testing.T) {
+func TestAWSCredential_BasicRequest(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 
@@ -567,7 +587,72 @@ func TestAwsCredential_BasicRequest(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_BasicRequestWithoutSecurityToken(t *testing.T) {
+func TestAWSCredential_IMDSv2(t *testing.T) {
+	validateSessionTokenHeaders := func(r *http.Request) {
+		if r.URL.Path == "/latest/api/token" {
+			headerValue := r.Header.Get(awsIMDSv2SessionTtlHeader)
+			if headerValue != awsIMDSv2SessionTtl {
+				t.Errorf("%q = \n%q\n want \n%q", awsIMDSv2SessionTtlHeader, headerValue, awsIMDSv2SessionTtl)
+			}
+		} else {
+			headerValue := r.Header.Get(awsIMDSv2SessionTokenHeader)
+			if headerValue != "sessiontoken" {
+				t.Errorf("%q = \n%q\n want \n%q", awsIMDSv2SessionTokenHeader, headerValue, "sessiontoken")
+			}
+		}
+	}
+
+	server := createAwsTestServer(
+		"/latest/meta-data/iam/security-credentials",
+		"/latest/meta-data/placement/availability-zone",
+		"https://sts.{region}.amazonaws.com?Action=GetCallerIdentity&Version=2011-06-15",
+		"/latest/api/token",
+		"gcp-aws-role",
+		"us-east-2b",
+		map[string]string{
+			"SecretAccessKey": secretAccessKey,
+			"AccessKeyId":     accessKeyID,
+			"Token":           securityToken,
+		},
+		"sessiontoken",
+		validateSessionTokenHeaders,
+	)
+	ts := httptest.NewServer(server)
+
+	tfc := testFileConfig
+	tfc.CredentialSource = server.getCredentialSource(ts.URL)
+
+	oldGetenv := getenv
+	defer func() { getenv = oldGetenv }()
+	getenv = setEnvironment(map[string]string{})
+	oldNow := now
+	defer func() { now = oldNow }()
+	now = setTime(defaultTime)
+
+	base, err := tfc.parse(context.Background())
+	if err != nil {
+		t.Fatalf("parse() failed %v", err)
+	}
+
+	out, err := base.subjectToken()
+	if err != nil {
+		t.Fatalf("retrieveSubjectToken() failed: %v", err)
+	}
+
+	expected := getExpectedSubjectToken(
+		"https://sts.us-east-2.amazonaws.com?Action=GetCallerIdentity&Version=2011-06-15",
+		"us-east-2",
+		accessKeyID,
+		secretAccessKey,
+		securityToken,
+	)
+
+	if got, want := out, expected; !reflect.DeepEqual(got, want) {
+		t.Errorf("subjectToken = \n%q\n want \n%q", got, want)
+	}
+}
+
+func TestAWSCredential_BasicRequestWithoutSecurityToken(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 	delete(server.Credentials, "Token")
@@ -605,7 +690,7 @@ func TestAwsCredential_BasicRequestWithoutSecurityToken(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_BasicRequestWithEnv(t *testing.T) {
+func TestAWSCredential_BasicRequestWithEnv(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 
@@ -646,7 +731,7 @@ func TestAwsCredential_BasicRequestWithEnv(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_BasicRequestWithDefaultEnv(t *testing.T) {
+func TestAWSCredential_BasicRequestWithDefaultEnv(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 
@@ -686,7 +771,7 @@ func TestAwsCredential_BasicRequestWithDefaultEnv(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_BasicRequestWithTwoRegions(t *testing.T) {
+func TestAWSCredential_BasicRequestWithTwoRegions(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 
@@ -727,7 +812,7 @@ func TestAwsCredential_BasicRequestWithTwoRegions(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_RequestWithBadVersion(t *testing.T) {
+func TestAWSCredential_RequestWithBadVersion(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 
@@ -748,7 +833,7 @@ func TestAwsCredential_RequestWithBadVersion(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_RequestWithNoRegionURL(t *testing.T) {
+func TestAWSCredential_RequestWithNoRegionURL(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 
@@ -775,7 +860,7 @@ func TestAwsCredential_RequestWithNoRegionURL(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_RequestWithBadRegionURL(t *testing.T) {
+func TestAWSCredential_RequestWithBadRegionURL(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 	server.WriteRegion = notFound
@@ -802,10 +887,10 @@ func TestAwsCredential_RequestWithBadRegionURL(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_RequestWithMissingCredential(t *testing.T) {
+func TestAWSCredential_RequestWithMissingCredential(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
-	server.WriteSecurityCredentials = func(w http.ResponseWriter) {
+	server.WriteSecurityCredentials = func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte("{}"))
 	}
 
@@ -831,10 +916,10 @@ func TestAwsCredential_RequestWithMissingCredential(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_RequestWithIncompleteCredential(t *testing.T) {
+func TestAWSCredential_RequestWithIncompleteCredential(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
-	server.WriteSecurityCredentials = func(w http.ResponseWriter) {
+	server.WriteSecurityCredentials = func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte(`{"AccessKeyId":"FOOBARBAS"}`))
 	}
 
@@ -860,7 +945,7 @@ func TestAwsCredential_RequestWithIncompleteCredential(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_RequestWithNoCredentialURL(t *testing.T) {
+func TestAWSCredential_RequestWithNoCredentialURL(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 
@@ -887,7 +972,7 @@ func TestAwsCredential_RequestWithNoCredentialURL(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_RequestWithBadCredentialURL(t *testing.T) {
+func TestAWSCredential_RequestWithBadCredentialURL(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 	server.WriteRolename = notFound
@@ -914,7 +999,7 @@ func TestAwsCredential_RequestWithBadCredentialURL(t *testing.T) {
 	}
 }
 
-func TestAwsCredential_RequestWithBadFinalCredentialURL(t *testing.T) {
+func TestAWSCredential_RequestWithBadFinalCredentialURL(t *testing.T) {
 	server := createDefaultAwsTestServer()
 	ts := httptest.NewServer(server)
 	server.WriteSecurityCredentials = notFound

google/internal/externalaccount/basecredentials.go

@@ -175,6 +175,7 @@ type CredentialSource struct {
 	RegionURL                   string `json:"region_url"`
 	RegionalCredVerificationURL string `json:"regional_cred_verification_url"`
 	CredVerificationURL         string `json:"cred_verification_url"`
+	IMDSv2SessionTokenURL       string `json:"imdsv2_session_token_url"`
 	Format                      format `json:"format"`
 }
 
@@ -185,14 +186,20 @@ func (c *Config) parse(ctx context.Context) (baseCredentialSource, error) {
 			if awsVersion != 1 {
 				return nil, fmt.Errorf("oauth2/google: aws version '%d' is not supported in the current build", awsVersion)
 			}
-			return awsCredentialSource{
+
+			awsCredSource := awsCredentialSource{
 				EnvironmentID:               c.CredentialSource.EnvironmentID,
 				RegionURL:                   c.CredentialSource.RegionURL,
 				RegionalCredVerificationURL: c.CredentialSource.RegionalCredVerificationURL,
 				CredVerificationURL:         c.CredentialSource.URL,
 				TargetResource:              c.Audience,
 				ctx:                         ctx,
-			}, nil
+			}
+			if c.CredentialSource.IMDSv2SessionTokenURL != "" {
+				awsCredSource.IMDSv2SessionTokenURL = c.CredentialSource.IMDSv2SessionTokenURL
+			}
+
+			return awsCredSource, nil
 		}
 	} else if c.CredentialSource.File != "" {
 		return fileCredentialSource{File: c.CredentialSource.File, Format: c.CredentialSource.Format}, nil