Use DescribeAlarmsForMetric with an AWS SDK or CLI

    /// <summary>
    /// Describe the current alarms for a specific metric.
    /// </summary>
    /// <param name="metricNamespace">The namespace of the metric.</param>
    /// <param name="metricName">The name of the metric.</param>
    /// <returns>The list of alarm data.</returns>
    public async Task<List<MetricAlarm>> DescribeAlarmsForMetric(string metricNamespace, string metricName)
    {
        var alarmsResult = await _amazonCloudWatch.DescribeAlarmsForMetricAsync(
            new DescribeAlarmsForMetricRequest()
            {
                Namespace = metricNamespace,
                MetricName = metricName
            });

        return alarmsResult.MetricAlarms;
    }

Include the required files.

#include <aws/core/Aws.h>
#include <aws/monitoring/CloudWatchClient.h>
#include <aws/monitoring/model/DescribeAlarmsRequest.h>
#include <aws/monitoring/model/DescribeAlarmsResult.h>
#include <iomanip>
#include <iostream>

Describe the alarms.

        Aws::CloudWatch::CloudWatchClient cw;
        Aws::CloudWatch::Model::DescribeAlarmsRequest request;
        request.SetMaxRecords(1);

        bool done = false;
        bool header = false;
        while (!done)
        {
            auto outcome = cw.DescribeAlarms(request);
            if (!outcome.IsSuccess())
            {
                std::cout << "Failed to describe CloudWatch alarms:" <<
                    outcome.GetError().GetMessage() << std::endl;
                break;
            }

            if (!header)
            {
                std::cout << std::left <<
                    std::setw(32) << "Name" <<
                    std::setw(64) << "Arn" <<
                    std::setw(64) << "Description" <<
                    std::setw(20) << "LastUpdated" <<
                    std::endl;
                header = true;
            }

            const auto &alarms = outcome.GetResult().GetMetricAlarms();
            for (const auto &alarm : alarms)
            {
                std::cout << std::left <<
                    std::setw(32) << alarm.GetAlarmName() <<
                    std::setw(64) << alarm.GetAlarmArn() <<
                    std::setw(64) << alarm.GetAlarmDescription() <<
                    std::setw(20) <<
                    alarm.GetAlarmConfigurationUpdatedTimestamp().ToGmtString(
                        SIMPLE_DATE_FORMAT_STR) <<
                    std::endl;
            }

            const auto &next_token = outcome.GetResult().GetNextToken();
            request.SetNextToken(next_token);
            done = next_token.empty();
        }

To display information about alarms associated with a metric

The following example uses the describe-alarms-for-metric command to display information about any alarms associated with the Amazon EC2 CPUUtilization metric and the instance with the ID i-0c986c72.:

aws cloudwatch describe-alarms-for-metric --metric-name CPUUtilization --namespace AWS/EC2 --dimensions Name=InstanceId,Value=i-0c986c72

Output:

{
    "MetricAlarms": [
        {
            "EvaluationPeriods": 10,
            "AlarmArn": "arn:aws:cloudwatch:us-east-1:111122223333:alarm:myHighCpuAlarm2",
            "StateUpdatedTimestamp": "2013-10-30T03:03:51.479Z",
            "AlarmConfigurationUpdatedTimestamp": "2013-10-30T03:03:50.865Z",
            "ComparisonOperator": "GreaterThanOrEqualToThreshold",
            "AlarmActions": [
                "arn:aws:sns:us-east-1:111122223333:NotifyMe"
            ],
            "Namespace": "AWS/EC2",
            "AlarmDescription": "CPU usage exceeds 70 percent",
            "StateReasonData": "{\"version\":\"1.0\",\"queryDate\":\"2013-10-30T03:03:51.479+0000\",\"startDate\":\"2013-10-30T02:08:00.000+0000\",\"statistic\":\"Average\",\"period\":300,\"recentDatapoints\":[40.698,39.612,42.432,39.796,38.816,42.28,42.854,40.088,40.760000000000005,41.316],\"threshold\":70.0}",
            "Period": 300,
            "StateValue": "OK",
            "Threshold": 70.0,
            "AlarmName": "myHighCpuAlarm2",
            "Dimensions": [
                {
                    "Name": "InstanceId",
                    "Value": "i-0c986c72"
                }
            ],
            "Statistic": "Average",
            "StateReason": "Threshold Crossed: 10 datapoints were not greater than or equal to the threshold (70.0). The most recent datapoints: [40.760000000000005, 41.316].",
            "InsufficientDataActions": [],
            "OKActions": [],
            "ActionsEnabled": true,
            "MetricName": "CPUUtilization"
        },
        {
            "EvaluationPeriods": 2,
            "AlarmArn": "arn:aws:cloudwatch:us-east-1:111122223333:alarm:myHighCpuAlarm",
            "StateUpdatedTimestamp": "2014-04-09T18:59:06.442Z",
            "AlarmConfigurationUpdatedTimestamp": "2014-04-09T22:26:05.958Z",
            "ComparisonOperator": "GreaterThanThreshold",
            "AlarmActions": [
                "arn:aws:sns:us-east-1:111122223333:HighCPUAlarm"
            ],
            "Namespace": "AWS/EC2",
            "AlarmDescription": "CPU usage exceeds 70 percent",
            "StateReasonData": "{\"version\":\"1.0\",\"queryDate\":\"2014-04-09T18:59:06.419+0000\",\"startDate\":\"2014-04-09T18:44:00.000+0000\",\"statistic\":\"Average\",\"period\":300,\"recentDatapoints\":[38.958,40.292],\"threshold\":70.0}",
            "Period": 300,
            "StateValue": "OK",
            "Threshold": 70.0,
            "AlarmName": "myHighCpuAlarm",
            "Dimensions": [
                {
                    "Name": "InstanceId",
                    "Value": "i-0c986c72"
                }
            ],
            "Statistic": "Average",
            "StateReason": "Threshold Crossed: 2 datapoints were not greater than the threshold (70.0). The most recent datapoints: [38.958, 40.292].",
            "InsufficientDataActions": [],
            "OKActions": [],
            "ActionsEnabled": false,
            "MetricName": "CPUUtilization"
        }
    ]
}

    /**
     * Checks for a metric alarm in AWS CloudWatch.
     *
     * @param fileName the name of the file containing the JSON configuration for the custom metric
     * @return a {@link CompletableFuture} that completes when the check for the metric alarm is complete
     */
    public CompletableFuture<Void> checkForMetricAlarmAsync(String fileName) {
        CompletableFuture<String> readFileFuture = CompletableFuture.supplyAsync(() -> {
            try {
                JsonParser parser = new JsonFactory().createParser(new File(fileName));
                com.fasterxml.jackson.databind.JsonNode rootNode = new ObjectMapper().readTree(parser);
                return rootNode.toString(); // Return JSON as a string for further processing
            } catch (IOException e) {
                throw new RuntimeException("Failed to read file", e);
            }
        });

        return readFileFuture.thenCompose(jsonContent -> {
            try {
                com.fasterxml.jackson.databind.JsonNode rootNode = new ObjectMapper().readTree(jsonContent);
                String customMetricNamespace = rootNode.findValue("customMetricNamespace").asText();
                String customMetricName = rootNode.findValue("customMetricName").asText();

                DescribeAlarmsForMetricRequest metricRequest = DescribeAlarmsForMetricRequest.builder()
                    .metricName(customMetricName)
                    .namespace(customMetricNamespace)
                    .build();

                return checkForAlarmAsync(metricRequest, customMetricName, 10);

            } catch (IOException e) {
                throw new RuntimeException("Failed to parse JSON content", e);
            }
        }).whenComplete((result, exception) -> {
            if (exception != null) {
                throw new RuntimeException("Error checking metric alarm", exception);
            }
        });
    }

    // Recursive method to check for the alarm.

    /**
     * Checks for the existence of an alarm asynchronously for the specified metric.
     *
     * @param metricRequest    the request to describe the alarms for the specified metric
     * @param customMetricName the name of the custom metric to check for an alarm
     * @param retries          the number of retries to perform if no alarm is found
     * @return a {@link CompletableFuture} that completes when an alarm is found or the maximum number of retries has been reached
     */
    private static CompletableFuture<Void> checkForAlarmAsync(DescribeAlarmsForMetricRequest metricRequest, String customMetricName, int retries) {
        if (retries == 0) {
            return CompletableFuture.completedFuture(null).thenRun(() ->
                logger.info("No Alarm state found for {} after 10 retries.", customMetricName)
            );
        }

        return (getAsyncClient().describeAlarmsForMetric(metricRequest).thenCompose(response -> {
            if (response.hasMetricAlarms()) {
                logger.info("Alarm state found for {}", customMetricName);
                return CompletableFuture.completedFuture(null); // Alarm found, complete the future
            } else {
                return CompletableFuture.runAsync(() -> {
                    try {
                        Thread.sleep(20000);
                        logger.info(".");
                    } catch (InterruptedException e) {
                        throw new RuntimeException("Interrupted while waiting to retry", e);
                    }
                }).thenCompose(v -> checkForAlarmAsync(metricRequest, customMetricName, retries - 1)); // Recursive call
            }
        }));
    }

Import the SDK and client modules and call the API.

import { DescribeAlarmsCommand } from "@aws-sdk/client-cloudwatch";
import { client } from "../libs/client.js";

const run = async () => {
  const command = new DescribeAlarmsCommand({
    AlarmNames: [process.env.CLOUDWATCH_ALARM_NAME], // Set the value of CLOUDWATCH_ALARM_NAME to the name of an existing alarm.
  });

  try {
    return await client.send(command);
  } catch (err) {
    console.error(err);
  }
};

export default run();

Create the client in a separate module and export it.

import { CloudWatchClient } from "@aws-sdk/client-cloudwatch";

export const client = new CloudWatchClient({});

// Load the AWS SDK for Node.js
var AWS = require("aws-sdk");
// Set the region
AWS.config.update({ region: "REGION" });

// Create CloudWatch service object
var cw = new AWS.CloudWatch({ apiVersion: "2010-08-01" });

cw.describeAlarms({ StateValue: "INSUFFICIENT_DATA" }, function (err, data) {
  if (err) {
    console.log("Error", err);
  } else {
    // List the names of all current alarms in the console
    data.MetricAlarms.forEach(function (item, index, array) {
      console.log(item.AlarmName);
    });
  }
});

suspend fun checkForMetricAlarm(fileName: String?) {
    // Read values from the JSON file.
    val parser = JsonFactory().createParser(File(fileName))
    val rootNode = ObjectMapper().readTree<JsonNode>(parser)
    val customMetricNamespace = rootNode.findValue("customMetricNamespace").asText()
    val customMetricName = rootNode.findValue("customMetricName").asText()
    var hasAlarm = false
    var retries = 10

    val metricRequest =
        DescribeAlarmsForMetricRequest {
            metricName = customMetricName
            namespace = customMetricNamespace
        }
    CloudWatchClient { region = "us-east-1" }.use { cwClient ->
        while (!hasAlarm && retries > 0) {
            val response = cwClient.describeAlarmsForMetric(metricRequest)
            if (response.metricAlarms?.count()!! > 0) {
                hasAlarm = true
            }
            retries--
            delay(20000)
            println(".")
        }
        if (!hasAlarm) {
            println("No Alarm state found for $customMetricName after 10 retries.")
        } else {
            println("Alarm state found for $customMetricName.")
        }
    }
}

class CloudWatchWrapper:
    """Encapsulates Amazon CloudWatch functions."""

    def __init__(self, cloudwatch_resource):
        """
        :param cloudwatch_resource: A Boto3 CloudWatch resource.
        """
        self.cloudwatch_resource = cloudwatch_resource


    def get_metric_alarms(self, metric_namespace, metric_name):
        """
        Gets the alarms that are currently watching the specified metric.

        :param metric_namespace: The namespace of the metric.
        :param metric_name: The name of the metric.
        :returns: An iterator that yields the alarms.
        """
        metric = self.cloudwatch_resource.Metric(metric_namespace, metric_name)
        alarm_iter = metric.alarms.all()
        logger.info("Got alarms for metric %s.%s.", metric_namespace, metric_name)
        return alarm_iter

#
# @param cloudwatch_client [Aws::CloudWatch::Client]
#   An initialized CloudWatch client.
# @example
#   describe_metric_alarms(Aws::CloudWatch::Client.new(region: 'us-east-1'))
def describe_metric_alarms(cloudwatch_client)
  response = cloudwatch_client.describe_alarms

  if response.metric_alarms.count.positive?
    response.metric_alarms.each do |alarm|
      puts '-' * 16
      puts "Name:           #{alarm.alarm_name}"
      puts "State value:    #{alarm.state_value}"
      puts "State reason:   #{alarm.state_reason}"
      puts "Metric:         #{alarm.metric_name}"
      puts "Namespace:      #{alarm.namespace}"
      puts "Statistic:      #{alarm.statistic}"
      puts "Period:         #{alarm.period}"
      puts "Unit:           #{alarm.unit}"
      puts "Eval. periods:  #{alarm.evaluation_periods}"
      puts "Threshold:      #{alarm.threshold}"
      puts "Comp. operator: #{alarm.comparison_operator}"

      if alarm.key?(:ok_actions) && alarm.ok_actions.count.positive?
        puts 'OK actions:'
        alarm.ok_actions.each do |a|
          puts "  #{a}"
        end
      end

      if alarm.key?(:alarm_actions) && alarm.alarm_actions.count.positive?
        puts 'Alarm actions:'
        alarm.alarm_actions.each do |a|
          puts "  #{a}"
        end
      end

      if alarm.key?(:insufficient_data_actions) &&
         alarm.insufficient_data_actions.count.positive?
        puts 'Insufficient data actions:'
        alarm.insufficient_data_actions.each do |a|
          puts "  #{a}"
        end
      end

      puts 'Dimensions:'
      if alarm.key?(:dimensions) && alarm.dimensions.count.positive?
        alarm.dimensions.each do |d|
          puts "  Name: #{d.name}, Value: #{d.value}"
        end
      else
        puts '  None for this alarm.'
      end
    end
  else
    puts 'No alarms found.'
  end
rescue StandardError => e
  puts "Error getting information about alarms: #{e.message}"
end

# Example usage:
def run_me
  region = ''

  # Print usage information and then stop.
  if ARGV[0] == '--help' || ARGV[0] == '-h'
    puts 'Usage:   ruby cw-ruby-example-show-alarms.rb REGION'
    puts 'Example: ruby cw-ruby-example-show-alarms.rb us-east-1'
    exit 1
  # If no values are specified at the command prompt, use these default values.
  elsif ARGV.count.zero?
    region = 'us-east-1'
  # Otherwise, use the values as specified at the command prompt.
  else
    region = ARGV[0]
  end

  cloudwatch_client = Aws::CloudWatch::Client.new(region: region)
  puts 'Available alarms:'
  describe_metric_alarms(cloudwatch_client)
end

run_me if $PROGRAM_NAME == __FILE__