Auto Scaling examples using SDK for C++ - Amazon SDK for C++
ActionsScenarios
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Auto Scaling examples using SDK for C++

The following code examples show you how to perform actions and implement common scenarios by using the Amazon SDK for C++ with Auto Scaling.

Actions are code excerpts from larger programs and must be run in context. While actions show you how to call individual service functions, you can see actions in context in their related scenarios and cross-service examples.

Scenarios are code examples that show you how to accomplish a specific task by calling multiple functions within the same service.

Each example includes a link to GitHub, where you can find instructions on how to set up and run the code in context.

Get started

The following code examples show how to get started using Auto Scaling.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository.

Code for the CMakeLists.txt CMake file.

# Set the minimum required version of CMake for this project.
cmake_minimum_required(VERSION 3.13)

# Set the AWS service components used by this project.
set(SERVICE_COMPONENTS autoscaling)

# Set this project's name.
project("hello_autoscaling")

# Set the C++ standard to use to build this target.
# At least C++ 11 is required for the AWS SDK for C++.
set(CMAKE_CXX_STANDARD 11)

# Use the MSVC variable to determine if this is a Windows build.
set(WINDOWS_BUILD ${MSVC})

if (WINDOWS_BUILD) # Set the location where CMake can find the installed libraries for the AWS SDK.
    string(REPLACE ";" "/aws-cpp-sdk-all;" SYSTEM_MODULE_PATH "${CMAKE_SYSTEM_PREFIX_PATH}/aws-cpp-sdk-all")
    list(APPEND CMAKE_PREFIX_PATH ${SYSTEM_MODULE_PATH})
endif ()

# Find the AWS SDK for C++ package.
find_package(AWSSDK REQUIRED COMPONENTS ${SERVICE_COMPONENTS})

if (WINDOWS_BUILD AND AWSSDK_INSTALL_AS_SHARED_LIBS)
     # Copy relevant AWS SDK for C++ libraries into the current binary directory for running and debugging.

     # set(BIN_SUB_DIR "/Debug") # If you are building from the command line, you may need to uncomment this 
                                    # and set the proper subdirectory to the executables' location.

     AWSSDK_CPY_DYN_LIBS(SERVICE_COMPONENTS "" ${CMAKE_CURRENT_BINARY_DIR}${BIN_SUB_DIR})
endif ()

add_executable(${PROJECT_NAME}
        hello_autoscaling.cpp)

target_link_libraries(${PROJECT_NAME}
        ${AWSSDK_LINK_LIBRARIES})

Code for the hello_autoscaling.cpp source file.

#include <aws/core/Aws.h>
#include <aws/autoscaling/AutoScalingClient.h>
#include <aws/autoscaling/model/DescribeAutoScalingGroupsRequest.h>
#include <iostream>

/*
 *  A "Hello Autoscaling" starter application which initializes an Amazon EC2 Auto Scaling client and describes the
 *  Amazon EC2 Auto Scaling groups.
 *
 *  main function
 *
 *  Usage: 'hello_autoscaling'
 *
 */

int main(int argc, char **argv) {
    Aws::SDKOptions options;
    // Optionally change the log level for debugging.
//   options.loggingOptions.logLevel = Utils::Logging::LogLevel::Debug;
    Aws::InitAPI(options); // Should only be called once.
    int result = 0;
    {
        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

        Aws::AutoScaling::AutoScalingClient autoscalingClient(clientConfig);

        std::vector<Aws::String> groupNames;
        Aws::String nextToken; // Used for pagination.

        do {

            Aws::AutoScaling::Model::DescribeAutoScalingGroupsRequest request;
            if (!nextToken.empty()) {
                request.SetNextToken(nextToken);
            }

            Aws::AutoScaling::Model::DescribeAutoScalingGroupsOutcome outcome =
                    autoscalingClient.DescribeAutoScalingGroups(request);

            if (outcome.IsSuccess()) {
                const Aws::Vector<Aws::AutoScaling::Model::AutoScalingGroup> &autoScalingGroups =
                        outcome.GetResult().GetAutoScalingGroups();
                for (auto &group: autoScalingGroups) {
                    groupNames.push_back(group.GetAutoScalingGroupName());
                }
                nextToken = outcome.GetResult().GetNextToken();
            } else {
                std::cerr << "Error with AutoScaling::DescribeAutoScalingGroups. "
                          << outcome.GetError().GetMessage()
                          << std::endl;
                result = 1;
                break;
            }
        } while (!nextToken.empty());

        std::cout << "Found " << groupNames.size() << " AutoScaling groups." << std::endl;
        for (auto &groupName: groupNames) {
            std::cout << "AutoScaling group: " << groupName << std::endl;
        }

    }


    Aws::ShutdownAPI(options); // Should only be called once.
    return result;
}

Actions

The following code example shows how to use CreateAutoScalingGroup.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

        Aws::AutoScaling::Model::CreateAutoScalingGroupRequest request;
        request.SetAutoScalingGroupName(groupName);
        Aws::Vector<Aws::String> availabilityGroupZones;
        availabilityGroupZones.push_back(
                availabilityZones[availabilityZoneChoice - 1].GetZoneName());
        request.SetAvailabilityZones(availabilityGroupZones);
        request.SetMaxSize(1);
        request.SetMinSize(1);

        Aws::AutoScaling::Model::LaunchTemplateSpecification launchTemplateSpecification;
        launchTemplateSpecification.SetLaunchTemplateName(templateName);
        request.SetLaunchTemplate(launchTemplateSpecification);

        Aws::AutoScaling::Model::CreateAutoScalingGroupOutcome outcome =
                autoScalingClient.CreateAutoScalingGroup(request);

        if (outcome.IsSuccess()) {
            std::cout << "Created Auto Scaling group '" << groupName << "'..."
                      << std::endl;
        }
        else if (outcome.GetError().GetErrorType() ==
                 Aws::AutoScaling::AutoScalingErrors::ALREADY_EXISTS_FAULT) {
            std::cout << "Auto Scaling group '" << groupName << "' already exists."
                      << std::endl;
        }
        else {
            std::cerr << "Error with AutoScaling::CreateAutoScalingGroup. "
                      << outcome.GetError().GetMessage()
                      << std::endl;

        }

The following code example shows how to use DeleteAutoScalingGroup.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

            Aws::AutoScaling::Model::DeleteAutoScalingGroupRequest request;
            request.SetAutoScalingGroupName(groupName);

            Aws::AutoScaling::Model::DeleteAutoScalingGroupOutcome outcome =
                    autoScalingClient.DeleteAutoScalingGroup(request);

            if (outcome.IsSuccess()) {
                std::cout << "Auto Scaling group '" << groupName << "' was deleted."
                          << std::endl;
            }
            else {
                std::cerr << "Error with AutoScaling::DeleteAutoScalingGroup. "
                          << outcome.GetError().GetMessage()
                          << std::endl;
                result = false;
            }
        }

The following code example shows how to use DescribeAutoScalingGroups.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

    Aws::AutoScaling::Model::DescribeAutoScalingGroupsRequest request;
    Aws::Vector<Aws::String> groupNames;
    groupNames.push_back(groupName);
    request.SetAutoScalingGroupNames(groupNames);

    Aws::AutoScaling::Model::DescribeAutoScalingGroupsOutcome outcome =
            client.DescribeAutoScalingGroups(request);

    if (outcome.IsSuccess()) {
        autoScalingGroup = outcome.GetResult().GetAutoScalingGroups();
    }
    else {
        std::cerr << "Error with AutoScaling::DescribeAutoScalingGroups. "
                  << outcome.GetError().GetMessage()
                  << std::endl;
    }

The following code example shows how to use DescribeAutoScalingInstances.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

        Aws::AutoScaling::Model::DescribeAutoScalingInstancesRequest request;
        request.SetInstanceIds(instanceIDs);

        Aws::AutoScaling::Model::DescribeAutoScalingInstancesOutcome outcome =
                client.DescribeAutoScalingInstances(request);

        if (outcome.IsSuccess()) {
            const Aws::Vector<Aws::AutoScaling::Model::AutoScalingInstanceDetails> &instancesDetails =
                    outcome.GetResult().GetAutoScalingInstances();

        }
        else {
            std::cerr << "Error with AutoScaling::DescribeAutoScalingInstances. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            return false;
        }

The following code example shows how to use DescribeScalingActivities.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

        Aws::AutoScaling::Model::DescribeScalingActivitiesRequest request;
        request.SetAutoScalingGroupName(groupName);

        Aws::Vector<Aws::AutoScaling::Model::Activity> allActivities;
        Aws::String nextToken; // Used for pagination;
        do {
            if (!nextToken.empty()) {
                request.SetNextToken(nextToken);
            }
            Aws::AutoScaling::Model::DescribeScalingActivitiesOutcome outcome =
                    autoScalingClient.DescribeScalingActivities(request);

            if (outcome.IsSuccess()) {
                const Aws::Vector<Aws::AutoScaling::Model::Activity> &activities =
                        outcome.GetResult().GetActivities();
                allActivities.insert(allActivities.end(), activities.begin(), activities.end());
                nextToken  = outcome.GetResult().GetNextToken();
            }
            else {
                std::cerr << "Error with AutoScaling::DescribeScalingActivities. "
                          << outcome.GetError().GetMessage()
                          << std::endl;

            }
        } while (!nextToken.empty());

        std::cout << "Found " << allActivities.size() << " activities."
                  << std::endl;
        std::cout << "Activities are ordered with the most recent first."
                  << std::endl;
        for (const Aws::AutoScaling::Model::Activity &activity: allActivities) {
            std::cout << activity.GetDescription() << std::endl;
            std::cout << activity.GetDetails() << std::endl;
        }

The following code example shows how to use DisableMetricsCollection.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

        Aws::AutoScaling::Model::DisableMetricsCollectionRequest request;
        request.SetAutoScalingGroupName(groupName);

        Aws::AutoScaling::Model::DisableMetricsCollectionOutcome outcome =
                autoScalingClient.DisableMetricsCollection(request);

        if (outcome.IsSuccess()) {
            std::cout << "Metrics collection has been disabled." << std::endl;
        }
        else {
            std::cerr << "Error with AutoScaling::DisableMetricsCollection. "
                      << outcome.GetError().GetMessage()
                      << std::endl;

        }

The following code example shows how to use EnableMetricsCollection.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

        Aws::AutoScaling::Model::EnableMetricsCollectionRequest request;
        request.SetAutoScalingGroupName(groupName);

        request.AddMetrics("GroupMinSize");
        request.AddMetrics("GroupMaxSize");
        request.AddMetrics("GroupDesiredCapacity");
        request.AddMetrics("GroupInServiceInstances");
        request.AddMetrics("GroupTotalInstances");
        request.SetGranularity("1Minute");

        Aws::AutoScaling::Model::EnableMetricsCollectionOutcome outcome =
                autoScalingClient.EnableMetricsCollection(request);
        if (outcome.IsSuccess()) {
            std::cout << "Auto Scaling metrics have been enabled."
                      << std::endl;
        }
        else {
            std::cerr << "Error with AutoScaling::EnableMetricsCollection. "
                      << outcome.GetError().GetMessage()
                      << std::endl;

        }

The following code example shows how to use SetDesiredCapacity.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

        Aws::AutoScaling::Model::SetDesiredCapacityRequest request;
        request.SetAutoScalingGroupName(groupName);
        request.SetDesiredCapacity(2);

        Aws::AutoScaling::Model::SetDesiredCapacityOutcome outcome =
                autoScalingClient.SetDesiredCapacity(request);

        if (!outcome.IsSuccess()) {
            std::cerr << "Error with AutoScaling::SetDesiredCapacityRequest. "
                      << outcome.GetError().GetMessage()
                      << std::endl;

        }

The following code example shows how to use TerminateInstanceInAutoScalingGroup.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

        Aws::AutoScaling::Model::TerminateInstanceInAutoScalingGroupRequest request;
        request.SetInstanceId(instanceIDs[instanceNumber - 1]);
        request.SetShouldDecrementDesiredCapacity(false);

        Aws::AutoScaling::Model::TerminateInstanceInAutoScalingGroupOutcome outcome =
                autoScalingClient.TerminateInstanceInAutoScalingGroup(request);

        if (outcome.IsSuccess()) {
            std::cout << "Waiting for EC2 instance with ID '"
                      << instanceIDs[instanceNumber - 1] << "' to terminate..."
                      << std::endl;
        }
        else {
            std::cerr << "Error with AutoScaling::TerminateInstanceInAutoScalingGroup. "
                      << outcome.GetError().GetMessage()
                      << std::endl;

        }

The following code example shows how to use UpdateAutoScalingGroup.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

        Aws::AutoScaling::Model::UpdateAutoScalingGroupRequest request;
        request.SetAutoScalingGroupName(groupName);
        request.SetMaxSize(3);

        Aws::AutoScaling::Model::UpdateAutoScalingGroupOutcome outcome =
                autoScalingClient.UpdateAutoScalingGroup(request);

        if (!outcome.IsSuccess()) {
            std::cerr << "Error with AutoScaling::UpdateAutoScalingGroup. "
                      << outcome.GetError().GetMessage()
                      << std::endl;

        }

Scenarios

The following code example shows how to:

  • Create an Amazon EC2 Auto Scaling group with a launch template and Availability Zones, and get information about running instances.

  • Enable Amazon CloudWatch metrics collection.

  • Update the group's desired capacity and wait for an instance to start.

  • Terminate an instance in the group.

  • List scaling activities that occur in response to user requests and capacity changes.

  • Get statistics for CloudWatch metrics, then clean up resources.

SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Amazon Code Examples Repository. 

//! Routine which demonstrates using an Auto Scaling group
//! to manage Amazon EC2 instances.
/*!
  \sa groupsAndInstancesScenario()
  \param clientConfig: AWS client configuration.
  \return bool: Successful completion.
 */
bool AwsDoc::AutoScaling::groupsAndInstancesScenario(
        const Aws::Client::ClientConfiguration &clientConfig) {
    Aws::String templateName;
    Aws::EC2::EC2Client ec2Client(clientConfig);

    std::cout << std::setfill('*') << std::setw(ASTERISK_FILL_WIDTH) << " "
              << std::endl;
    std::cout
            << "Welcome to the Amazon Elastic Compute Cloud (Amazon EC2) Auto Scaling "
            << "demo for managing groups and instances." << std::endl;
    std::cout << std::setfill('*') << std::setw(ASTERISK_FILL_WIDTH) << " \n"
              << std::endl;

    std::cout << "This example requires an EC2 launch template." << std::endl;
    if (askYesNoQuestion(
            "Would you like to use an existing EC2 launch template (y/n)?  ")) {

        // 1. Specify the name of an existing EC2 launch template.
        templateName = askQuestion(
                "Enter the name of the existing EC2 launch template.  ");

        Aws::EC2::Model::DescribeLaunchTemplatesRequest request;
        request.AddLaunchTemplateNames(templateName);
        Aws::EC2::Model::DescribeLaunchTemplatesOutcome outcome =
                ec2Client.DescribeLaunchTemplates(request);

        if (outcome.IsSuccess()) {
            std::cout << "Validated the EC2 launch template '" << templateName
                      << "' exists by calling DescribeLaunchTemplate." << std::endl;
        }
        else {
            std::cerr << "Error validating the existence of the launch template. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
        }
    }
    else { // 2.  Or create a new EC2 launch template.
        templateName = askQuestion("Enter the name for a new EC2 launch template: ");

        Aws::EC2::Model::CreateLaunchTemplateRequest request;
        request.SetLaunchTemplateName(templateName);

        Aws::EC2::Model::RequestLaunchTemplateData requestLaunchTemplateData;
        requestLaunchTemplateData.SetInstanceType(EC2_LAUNCH_TEMPLATE_INSTANCE_TYPE);
        requestLaunchTemplateData.SetImageId(EC2_LAUNCH_TEMPLATE_IMAGE_ID);

        request.SetLaunchTemplateData(requestLaunchTemplateData);

        Aws::EC2::Model::CreateLaunchTemplateOutcome outcome =
                ec2Client.CreateLaunchTemplate(request);

        if (outcome.IsSuccess()) {
            std::cout << "The EC2 launch template '" << templateName << " was created."
                      << std::endl;
        }
        else if (outcome.GetError().GetExceptionName() ==
                 "InvalidLaunchTemplateName.AlreadyExistsException") {
            std::cout << "The EC2 template '" << templateName << "' already exists"
                      << std::endl;
        }
        else {
            std::cerr << "Error with EC2::CreateLaunchTemplate. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
        }
    }
    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);
    std::cout << "Let's create an Auto Scaling group." << std::endl;
    Aws::String groupName = askQuestion(
            "Enter a name for the Auto Scaling group:  ");
    // 3. Retrieve a list of EC2 Availability Zones.
    Aws::Vector<Aws::EC2::Model::AvailabilityZone> availabilityZones;
    {
        Aws::EC2::Model::DescribeAvailabilityZonesRequest request;

        Aws::EC2::Model::DescribeAvailabilityZonesOutcome outcome =
                ec2Client.DescribeAvailabilityZones(request);

        if (outcome.IsSuccess()) {
            std::cout
                    << "EC2 instances can be created in the following Availability Zones:"
                    << std::endl;

            availabilityZones = outcome.GetResult().GetAvailabilityZones();
            for (size_t i = 0; i < availabilityZones.size(); ++i) {
                std::cout << "   " << i + 1 << ".  "
                          << availabilityZones[i].GetZoneName() << std::endl;
            }
        }
        else {
            std::cerr << "Error with EC2::DescribeAvailabilityZones. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            cleanupResources("", templateName, autoScalingClient, ec2Client);
            return false;
        }
    }

    int availabilityZoneChoice = askQuestionForIntRange(
            "Choose an Availability Zone:  ", 1,
            static_cast<int>(availabilityZones.size()));
    // 4. Create an Auto Scaling group with the specified Availability Zone.
    {
        Aws::AutoScaling::Model::CreateAutoScalingGroupRequest request;
        request.SetAutoScalingGroupName(groupName);
        Aws::Vector<Aws::String> availabilityGroupZones;
        availabilityGroupZones.push_back(
                availabilityZones[availabilityZoneChoice - 1].GetZoneName());
        request.SetAvailabilityZones(availabilityGroupZones);
        request.SetMaxSize(1);
        request.SetMinSize(1);

        Aws::AutoScaling::Model::LaunchTemplateSpecification launchTemplateSpecification;
        launchTemplateSpecification.SetLaunchTemplateName(templateName);
        request.SetLaunchTemplate(launchTemplateSpecification);

        Aws::AutoScaling::Model::CreateAutoScalingGroupOutcome outcome =
                autoScalingClient.CreateAutoScalingGroup(request);

        if (outcome.IsSuccess()) {
            std::cout << "Created Auto Scaling group '" << groupName << "'..."
                      << std::endl;
        }
        else if (outcome.GetError().GetErrorType() ==
                 Aws::AutoScaling::AutoScalingErrors::ALREADY_EXISTS_FAULT) {
            std::cout << "Auto Scaling group '" << groupName << "' already exists."
                      << std::endl;
        }
        else {
            std::cerr << "Error with AutoScaling::CreateAutoScalingGroup. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            cleanupResources("", templateName, autoScalingClient, ec2Client);
            return false;
        }
    }

    Aws::Vector<Aws::AutoScaling::Model::AutoScalingGroup> autoScalingGroups;
    if (AwsDoc::AutoScaling::describeGroup(groupName, autoScalingGroups,
                                           autoScalingClient)) {
        std::cout << "Here is the Auto Scaling group description." << std::endl;
        if (!autoScalingGroups.empty()) {
            logAutoScalingGroupInfo(autoScalingGroups);
        }
    }
    else {
        cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
        return false;
    }

    std::cout
            << "Waiting for the EC2 instance in the Auto Scaling group to become active..."
            << std::endl;
    if (!waitForInstances(groupName, autoScalingGroups, autoScalingClient)) {
        cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
        return false;
    }

    bool enableMetrics = askYesNoQuestion(
            "Do you want to collect metrics about the A"
            "Auto Scaling group during this demo (y/n)?  ");
    // 7. Optionally enable metrics collection for the Auto Scaling group.
    if (enableMetrics) {
        Aws::AutoScaling::Model::EnableMetricsCollectionRequest request;
        request.SetAutoScalingGroupName(groupName);

        request.AddMetrics("GroupMinSize");
        request.AddMetrics("GroupMaxSize");
        request.AddMetrics("GroupDesiredCapacity");
        request.AddMetrics("GroupInServiceInstances");
        request.AddMetrics("GroupTotalInstances");
        request.SetGranularity("1Minute");

        Aws::AutoScaling::Model::EnableMetricsCollectionOutcome outcome =
                autoScalingClient.EnableMetricsCollection(request);
        if (outcome.IsSuccess()) {
            std::cout << "Auto Scaling metrics have been enabled."
                      << std::endl;
        }
        else {
            std::cerr << "Error with AutoScaling::EnableMetricsCollection. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
            return false;
        }
    }

    std::cout << "Let's update the maximum number of EC2 instances in '" << groupName <<
              "' from 1 to 3." << std::endl;
    askQuestion("Press enter to continue:  ", alwaysTrueTest);
    // 8. Update the Auto Scaling group, setting a new maximum size.
    {
        Aws::AutoScaling::Model::UpdateAutoScalingGroupRequest request;
        request.SetAutoScalingGroupName(groupName);
        request.SetMaxSize(3);

        Aws::AutoScaling::Model::UpdateAutoScalingGroupOutcome outcome =
                autoScalingClient.UpdateAutoScalingGroup(request);

        if (!outcome.IsSuccess()) {
            std::cerr << "Error with AutoScaling::UpdateAutoScalingGroup. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
            return false;
        }
    }

    if (AwsDoc::AutoScaling::describeGroup(groupName, autoScalingGroups,
                                           autoScalingClient)) {
        if (!autoScalingGroups.empty()) {
            const auto &instances = autoScalingGroups[0].GetInstances();
            std::cout
                    << "The group still has one running EC2 instance, but it can have up to 3.\n"
                    << std::endl;
            logAutoScalingGroupInfo(autoScalingGroups);
        }
        else {
            std::cerr
                    << "No EC2 launch groups were retrieved from DescribeGroup request."
                    << std::endl;
            cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
            return false;
        }
    }

    std::cout << "\n" << std::setfill('*') << std::setw(ASTERISK_FILL_WIDTH) << "\n"
              << std::endl;
    std::cout << "Let's update the desired capacity in '" << groupName <<
              "' from 1 to 2." << std::endl;
    askQuestion("Press enter to continue:  ", alwaysTrueTest);
    //  9. Update the Auto Scaling group, setting a new desired capacity.
    {
        Aws::AutoScaling::Model::SetDesiredCapacityRequest request;
        request.SetAutoScalingGroupName(groupName);
        request.SetDesiredCapacity(2);

        Aws::AutoScaling::Model::SetDesiredCapacityOutcome outcome =
                autoScalingClient.SetDesiredCapacity(request);

        if (!outcome.IsSuccess()) {
            std::cerr << "Error with AutoScaling::SetDesiredCapacityRequest. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
            return false;
        }
    }

    if (AwsDoc::AutoScaling::describeGroup(groupName, autoScalingGroups,
                                           autoScalingClient)) {
        if (!autoScalingGroups.empty()) {
            std::cout
                    << "Here is the current state of the group." << std::endl;
            logAutoScalingGroupInfo(autoScalingGroups);
        }
        else {
            std::cerr
                    << "No EC2 launch groups were retrieved from DescribeGroup request."
                    << std::endl;
            cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
            return false;
        }
    }

    std::cout << "Waiting for the new EC2 instance to start..." << std::endl;
    waitForInstances(groupName, autoScalingGroups, autoScalingClient);

    std::cout << "\n" << std::setfill('*') << std::setw(ASTERISK_FILL_WIDTH) << "\n"
              << std::endl;

    std::cout << "Let's terminate one of the EC2 instances in " << groupName << "."
              << std::endl;
    std::cout << "Because the desired capacity is 2, another EC2 instance will start "
              << "to replace the terminated EC2 instance."
              << std::endl;
    std::cout << "The currently running EC2 instances are:" << std::endl;

    if (autoScalingGroups.empty()) {
        std::cerr << "Error describing groups. No groups returned." << std::endl;
        cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
        return false;
    }

    int instanceNumber = 1;
    Aws::Vector<Aws::String> instanceIDs = instancesToInstanceIDs(
            autoScalingGroups[0].GetInstances());
    for (const Aws::String &instanceID: instanceIDs) {
        std::cout << "   " << instanceNumber << ". " << instanceID << std::endl;
        ++instanceNumber;
    }

    instanceNumber = askQuestionForIntRange("Which EC2 instance do you want to stop? ",
                                            1,
                                            static_cast<int>(instanceIDs.size()));

    // 10. Terminate an EC2 instance in the Auto Scaling group.
    {
        Aws::AutoScaling::Model::TerminateInstanceInAutoScalingGroupRequest request;
        request.SetInstanceId(instanceIDs[instanceNumber - 1]);
        request.SetShouldDecrementDesiredCapacity(false);

        Aws::AutoScaling::Model::TerminateInstanceInAutoScalingGroupOutcome outcome =
                autoScalingClient.TerminateInstanceInAutoScalingGroup(request);

        if (outcome.IsSuccess()) {
            std::cout << "Waiting for EC2 instance with ID '"
                      << instanceIDs[instanceNumber - 1] << "' to terminate..."
                      << std::endl;
        }
        else {
            std::cerr << "Error with AutoScaling::TerminateInstanceInAutoScalingGroup. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
            return false;
        }
    }

    waitForInstances(groupName, autoScalingGroups, autoScalingClient);

    std::cout << "\n" << std::setfill('*') << std::setw(ASTERISK_FILL_WIDTH) << "\n"
              << std::endl;
    std::cout << "Let's get a report of scaling activities for EC2 launch group '"
              << groupName << "'."
              << std::endl;
    askQuestion("Press enter to continue:  ", alwaysTrueTest);
    // 11. Get a description of activities for the Auto Scaling group.
    {
        Aws::AutoScaling::Model::DescribeScalingActivitiesRequest request;
        request.SetAutoScalingGroupName(groupName);

        Aws::Vector<Aws::AutoScaling::Model::Activity> allActivities;
        Aws::String nextToken; // Used for pagination;
        do {
            if (!nextToken.empty()) {
                request.SetNextToken(nextToken);
            }
            Aws::AutoScaling::Model::DescribeScalingActivitiesOutcome outcome =
                    autoScalingClient.DescribeScalingActivities(request);

            if (outcome.IsSuccess()) {
                const Aws::Vector<Aws::AutoScaling::Model::Activity> &activities =
                        outcome.GetResult().GetActivities();
                allActivities.insert(allActivities.end(), activities.begin(), activities.end());
                nextToken  = outcome.GetResult().GetNextToken();
            }
            else {
                std::cerr << "Error with AutoScaling::DescribeScalingActivities. "
                          << outcome.GetError().GetMessage()
                          << std::endl;
                cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
                return false;
            }
        } while (!nextToken.empty());

        std::cout << "Found " << allActivities.size() << " activities."
                  << std::endl;
        std::cout << "Activities are ordered with the most recent first."
                  << std::endl;
        for (const Aws::AutoScaling::Model::Activity &activity: allActivities) {
            std::cout << activity.GetDescription() << std::endl;
            std::cout << activity.GetDetails() << std::endl;
        }
    }

    if (enableMetrics) {
        if (!logAutoScalingMetrics(groupName, clientConfig)) {
            cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
            return false;
        }
    }

    std::cout << "Let's  clean up." << std::endl;
    askQuestion("Press enter to continue:  ", alwaysTrueTest);

    // 13. Disable metrics collection if enabled.
    if (enableMetrics) {
        Aws::AutoScaling::Model::DisableMetricsCollectionRequest request;
        request.SetAutoScalingGroupName(groupName);

        Aws::AutoScaling::Model::DisableMetricsCollectionOutcome outcome =
                autoScalingClient.DisableMetricsCollection(request);

        if (outcome.IsSuccess()) {
            std::cout << "Metrics collection has been disabled." << std::endl;
        }
        else {
            std::cerr << "Error with AutoScaling::DisableMetricsCollection. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
            return false;
        }
    }

    return cleanupResources(groupName, templateName, autoScalingClient, ec2Client);
}

//! Routine which waits for EC2 instances in an Auto Scaling group to
//! complete startup or shutdown.
/*!
 \sa waitForInstances()
 \param groupName: An Auto Scaling group name.
 \param autoScalingGroups: Vector to receive 'AutoScalingGroup' records.
 \param client: 'AutoScalingClient' instance.
 \return bool: Successful completion.
 */
bool AwsDoc::AutoScaling::waitForInstances(const Aws::String &groupName,
                                           Aws::Vector<Aws::AutoScaling::Model::AutoScalingGroup> &autoScalingGroups,
                                           const Aws::AutoScaling::AutoScalingClient &client) {
    bool ready = false;
    const std::vector<Aws::String> READY_STATES = {"InService", "Terminated"};

    int count = 0;
    int desiredCapacity = 0;
    std::this_thread::sleep_for(std::chrono::seconds(4));
    while (!ready) {
        if (WAIT_FOR_INSTANCES_TIMEOUT < count) {
            std::cerr << "Wait for instance timed out." << std::endl;
            return false;
        }

        std::this_thread::sleep_for(std::chrono::seconds(1));
        ++count;
        if (!describeGroup(groupName, autoScalingGroups, client)) {
            return false;
        }
        Aws::Vector<Aws::String> instanceIDs;
        if (!autoScalingGroups.empty()) {
            instanceIDs = instancesToInstanceIDs(autoScalingGroups[0].GetInstances());
            desiredCapacity = autoScalingGroups[0].GetDesiredCapacity();
        }

        if (instanceIDs.empty()) {
            if (desiredCapacity == 0) {
                break;
            }
            else {
                if ((count % 5) == 0) {
                    std::cout << "No instance IDs returned for group." << std::endl;
                }

                continue;
            }
        }

        // 6.  Check lifecycle state of the instances using DescribeAutoScalingInstances.
        Aws::AutoScaling::Model::DescribeAutoScalingInstancesRequest request;
        request.SetInstanceIds(instanceIDs);

        Aws::AutoScaling::Model::DescribeAutoScalingInstancesOutcome outcome =
                client.DescribeAutoScalingInstances(request);

        if (outcome.IsSuccess()) {
            const Aws::Vector<Aws::AutoScaling::Model::AutoScalingInstanceDetails> &instancesDetails =
                    outcome.GetResult().GetAutoScalingInstances();
            ready = instancesDetails.size() >= desiredCapacity;
            for (const Aws::AutoScaling::Model::AutoScalingInstanceDetails &details: instancesDetails) {
                if (!stringInVector(details.GetLifecycleState(), READY_STATES)) {
                    ready = false;
                    break;
                }
            }
            // Log the status while waiting.
            if (((count % 5) == 1) || ready) {
                logInstancesLifecycleState(instancesDetails);
            }
        }
        else {
            std::cerr << "Error with AutoScaling::DescribeAutoScalingInstances. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            return false;
        }
    }

    if (!describeGroup(groupName, autoScalingGroups, client)) {
        return false;
    }

    return true;
}

//! Routine to cleanup resources created in 'groupsAndInstancesScenario'.
/*!
 \sa cleanupResources()
 \param groupName: Optional Auto Scaling group name.
 \param templateName: Optional EC2 launch template name.
 \param autoScalingClient: 'AutoScalingClient' instance.
 \param ec2Client: 'EC2Client' instance.
\return bool: Successful completion.
 */
bool AwsDoc::AutoScaling::cleanupResources(const Aws::String &groupName,
                                           const Aws::String &templateName,
                                           const Aws::AutoScaling::AutoScalingClient &autoScalingClient,
                                           const Aws::EC2::EC2Client &ec2Client) {
    bool result = true;

    // 14. Delete the Auto Scaling group.
    if (!groupName.empty() &&
        (askYesNoQuestion(
                Aws::String("Delete the Auto Scaling group '") + groupName +
                "'  (y/n)?"))) {
        {
            Aws::AutoScaling::Model::UpdateAutoScalingGroupRequest request;
            request.SetAutoScalingGroupName(groupName);
            request.SetMinSize(0);
            request.SetDesiredCapacity(0);

            Aws::AutoScaling::Model::UpdateAutoScalingGroupOutcome outcome =
                    autoScalingClient.UpdateAutoScalingGroup(request);

            if (outcome.IsSuccess()) {
                std::cout
                        << "The minimum size and desired capacity of the Auto Scaling group "
                        << "was set to zero before terminating the instances."
                        << std::endl;
            }
            else {
                std::cerr << "Error with AutoScaling::UpdateAutoScalingGroup. "
                          << outcome.GetError().GetMessage() << std::endl;
                result = false;
            }
        }

        Aws::Vector<Aws::AutoScaling::Model::AutoScalingGroup> autoScalingGroups;
        if (AwsDoc::AutoScaling::describeGroup(groupName, autoScalingGroups,
                                               autoScalingClient)) {
            if (!autoScalingGroups.empty()) {
                Aws::Vector<Aws::String> instanceIDs = instancesToInstanceIDs(
                        autoScalingGroups[0].GetInstances());
                for (const Aws::String &instanceID: instanceIDs) {
                    Aws::AutoScaling::Model::TerminateInstanceInAutoScalingGroupRequest request;
                    request.SetInstanceId(instanceID);
                    request.SetShouldDecrementDesiredCapacity(true);

                    Aws::AutoScaling::Model::TerminateInstanceInAutoScalingGroupOutcome outcome =
                            autoScalingClient.TerminateInstanceInAutoScalingGroup(
                                    request);

                    if (outcome.IsSuccess()) {
                        std::cout << "Initiating termination of EC2 instance '"
                                  << instanceID << "'." << std::endl;
                    }
                    else {
                        std::cerr
                                << "Error with AutoScaling::TerminateInstanceInAutoScalingGroup. "
                                << outcome.GetError().GetMessage() << std::endl;
                        result = false;
                    }
                }
            }

            std::cout
                    << "Waiting for the EC2 instances to terminate before deleting the "
                    << "Auto Scaling group..." << std::endl;
            waitForInstances(groupName, autoScalingGroups, autoScalingClient);
        }

        {
            Aws::AutoScaling::Model::DeleteAutoScalingGroupRequest request;
            request.SetAutoScalingGroupName(groupName);

            Aws::AutoScaling::Model::DeleteAutoScalingGroupOutcome outcome =
                    autoScalingClient.DeleteAutoScalingGroup(request);

            if (outcome.IsSuccess()) {
                std::cout << "Auto Scaling group '" << groupName << "' was deleted."
                          << std::endl;
            }
            else {
                std::cerr << "Error with AutoScaling::DeleteAutoScalingGroup. "
                          << outcome.GetError().GetMessage()
                          << std::endl;
                result = false;
            }
        }
    }

    // 15. Delete the EC2 launch template.
    if (!templateName.empty() && (askYesNoQuestion(
            Aws::String("Delete the EC2 launch template '") + templateName +
            "' (y/n)?"))) {
        Aws::EC2::Model::DeleteLaunchTemplateRequest request;
        request.SetLaunchTemplateName(templateName);

        Aws::EC2::Model::DeleteLaunchTemplateOutcome outcome =
                ec2Client.DeleteLaunchTemplate(request);

        if (outcome.IsSuccess()) {
            std::cout << "EC2 launch template '" << templateName << "' was deleted."
                      << std::endl;
        }
        else {
            std::cerr << "Error with EC2::DeleteLaunchTemplate. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            result = false;
        }
    }

    return result;
}

//! Routine which retrieves Auto Scaling group descriptions.
/*!
 \sa describeGroup()
 \param groupName: An Auto Scaling group name.
 \param autoScalingGroups: Vector to receive 'AutoScalingGroup' records.
 \param client: 'AutoScalingClient' instance.
 \return bool: Successful completion.
 */
bool AwsDoc::AutoScaling::describeGroup(const Aws::String &groupName,
                                        Aws::Vector<Aws::AutoScaling::Model::AutoScalingGroup> &autoScalingGroup,
                                        const Aws::AutoScaling::AutoScalingClient &client) {
    // 5. Retrieve a description of the Auto Scaling group.
    Aws::AutoScaling::Model::DescribeAutoScalingGroupsRequest request;
    Aws::Vector<Aws::String> groupNames;
    groupNames.push_back(groupName);
    request.SetAutoScalingGroupNames(groupNames);

    Aws::AutoScaling::Model::DescribeAutoScalingGroupsOutcome outcome =
            client.DescribeAutoScalingGroups(request);

    if (outcome.IsSuccess()) {
        autoScalingGroup = outcome.GetResult().GetAutoScalingGroups();
    }
    else {
        std::cerr << "Error with AutoScaling::DescribeAutoScalingGroups. "
                  << outcome.GetError().GetMessage()
                  << std::endl;
    }

    return outcome.IsSuccess();
}