Get-CWAlarm issue with CompositeAlarm

[zewar96]

Description

When running Get-CWAlarm -AlarmType "CompositeAlarm" I expect to receive all composite alarms created within my account. This actually returns no information from the call. However, when running the same command in the CLI it returns the 2 alarms

Reproduction Steps

Using version 4.1.9
Make sure you have at least 1 composite alarm setup in your account
Run:
Get-CWAlarm -AlarmType "CompositeAlarm"

I get no results. However, If i run:
aws cloudwatch describe-alarms --alarm-types "CompositeAlarm"
I get the 2 composite alarms i have setup

Running the powershell command with -AlarmType "MetricAlarm" returns all individual alarms without issue

Logs

I have enabled logging and was able to see the repsonse is actually returning the information in the repsonse (at least the first 1024 bytes), but for some reason the function doesn't return anything

Environment

• Build Version: 4.1.9
• OS Info: Windows 10
• Build Environment:
• Targeted .NET Platform:

Resolution

• 👋 I can/would-like-to implement a fix for this problem myself

---

This is a 🐛 bug-report

[ashishdhingra]

Get-CWAlarm -AlarmType @('CompositeAlarm', 'MetricAlarm') works but only returns metric alarms. Kindly note that -AlarmType is a string array.

The below C# code utilizing AWSSDK.CloudWatch, correctly returns the alarms in CompositeAlarms and MetricAlarms properties.

using System.Collections.Generic;
using Amazon.CloudWatch;
using Amazon.CloudWatch.Model;

namespace CloudWatchAlarmListTest
{
    class Program
    {
        static void Main(string[] args)
        {
            AmazonCloudWatchClient amazonCloudWatchClient = new AmazonCloudWatchClient();
            var result =  amazonCloudWatchClient.DescribeAlarmsAsync(new DescribeAlarmsRequest() {
                AlarmTypes = new List<string>() { "CompositeAlarm", "MetricAlarm" } }
            ).Result;
        }
    }
}

Not sure if PowerShell is considering both CompositeAlarms and MetricAlarms properties from the service response.

[ashishdhingra]

Findings: (for Get-CWAlarm-Cmdlet)

• When using Modular command, GetCWAlarmCmdlet.Execute() method is executed.
• Parameter AlarmType is properly bound to the CmdLet context.
• CallAWSServiceOperation() is executed which correctly returns composite alarm in CompositeAlarms property list.
• Execution of pipelineOutput = cmdletContext.Select(response, this) constructs the output by executing CmdletContext.Select().
• The CmdletContext.Select() is developed to return response.MetricAlarms.

Hence, CompositeAlarms returned by service are never returned in output.

Possible Solution
Change the Select delegate property for GetCWAlarmCmdlet::CmdletContext to:

public System.Func<Amazon.CloudWatch.Model.DescribeAlarmsResponse, GetCWAlarmCmdlet, object> Select { get; set; } =
        (response, cmdlet) =>
        {
            List<object> alarms = new List<object>();
            if (response.CompositeAlarms != null && response.CompositeAlarms.Count > 0) alarms.AddRange(response.CompositeAlarms);
            if (response.MetricAlarms != null && response.MetricAlarms.Count > 0) alarms.AddRange(response.MetricAlarms);

            return alarms;
        };

[ashishdhingra]

Hi @zewar96,

Good afternoon.

Please try using the -Select parameter with value CompositeAlarm as a workaround and see if works. For example the below command selects the CompositeAlarms from output:

Get-CWAlarm  -AlarmType @('MetricAlarm', 'CompositeAlarm') -Select 'CompositeAlarms' 

OR

Get-CWAlarm  -AlarmType 'CompositeAlarm' -Select 'CompositeAlarms' 

In case you need to select both CompositeAlarms and MetricAlarms, use -Select with value *:

Get-CWAlarm  -AlarmType @('MetricAlarm', 'CompositeAlarm') -Select '*' 

This would return an object with CompositeAlarms and MetricAlarms properties.

Hope this helps.

Thanks,
Ashish

[zewar96]

@ashishdhingra This will work fine until the code is corrected. Thanks for the work around!

[github-actions]

We have noticed this issue has not received attention in 1 year. We will close this issue for now. If you think this is in error, please feel free to comment and reopen the issue.

[ashishdhingra]

No close.

[ashishdhingra]

In monitoring.xml service model config, DescribeAlarms is configured with OutputProperty as MetricAlarms. CmdletSourceWriter uses WriteContextClass() method to use OutputProperty as part of Select delegate here.

To implement this breaking change:

• Either we move this CmdLet from Basic to Advanced folder to hand-craft the logic. This should be excluded from generator process; OR
• Support multiple output properties and generate the logic proposed in Get-CWAlarm issue with CompositeAlarm #206 (comment). However, we would somehow need to inspect the return type of output properties.