use expired credentials from IMDS if none exist

Author: sbiscigl

src/aws-cpp-sdk-core/source/config/EC2InstanceProfileConfigLoader.cpp

@@ -79,7 +79,7 @@ namespace Aws
             auto credentialsView = credentialsDoc.View();
             DateTime expirationTime(credentialsView.GetString(expiration), Aws::Utils::DateFormat::ISO_8601);
             // re-use old credentials and not block if the IMDS call failed or if the latest credential is in the past
-            if (expirationTime.WasParseSuccessful() && DateTime::Now() > expirationTime) {
+            if (expirationTime.WasParseSuccessful() && DateTime::Now() > expirationTime && m_profiles.find(INSTANCE_PROFILE_KEY) != m_profiles.end()) {
                 AWS_LOGSTREAM_ERROR(EC2_INSTANCE_PROFILE_LOG_TAG,
                                     "Expiration Time of Credentials in the past, refusing to update credentials");
                 this->credentialsValidUntilMillis = DateTime::Now().Millis() + calculateRetryTime();

tests/aws-cpp-sdk-core-tests/aws/auth/AWSCredentialsProviderTest.cpp

@@ -428,6 +428,17 @@ TEST_F(InstanceProfileCredentialsProviderTest, TestEC2MetadataClientReturnsBadDa
     ASSERT_EQ("", provider.GetAWSCredentials().GetAWSSecretKey());
 }
 
+TEST_F(InstanceProfileCredentialsProviderTest, TestUsesExpiredCredentialsIfNoneExist) {
+  auto mockClient = Aws::MakeShared<MockEC2MetadataClient>(AllocationTag);
+
+  const char* validCredentials = R"({ "AccessKeyId": "goodAccessKey", "SecretAccessKey": "goodSecretKey", "Token": "goodToken", "Code": "Success", "Expiration": "1991-04-19T06:12:00Z" })";
+  mockClient->SetMockedCredentialsValue(validCredentials);
+
+  InstanceProfileCredentialsProvider provider(Aws::MakeShared<Aws::Config::EC2InstanceProfileConfigLoader>(AllocationTag, mockClient), 10);
+  ASSERT_EQ("goodAccessKey", provider.GetAWSCredentials().GetAWSAccessKeyId());
+  ASSERT_EQ("goodSecretKey", provider.GetAWSCredentials().GetAWSSecretKey());
+}
+
 static Aws::String WrapEchoStringWithSingleQuoteForUnixShell(Aws::String str)
 {
 #ifndef _WIN32