Adding dimensions to metrics in PutMetricDataRequest results in a MalformedInput exception

When constructing a MetricDatum for CloudWatch, it seems that adding any dimensions to the metric will result in errors upon attempting to submit the data to CloudWatch via the CloudWatchClient.PutMetricData(...) function.

It looks like the issue is that the output format generated by the CloudWatchClient does not match the specification here:

https://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/API_PutMetricData.html

The code below generates the following request body:

Action=PutMetricData
&Namespace=MyMetricTest
&MetricData.member.1.MetricName=MyMetricName
&MetricData.member.1.Dimensions.Name=MyDimensionName
&MetricData.member.1.Dimensions.Value=MyDimensionValue
&MetricData.member.1.Value=100
&Version=2010-08-01

But according to the specification, it looks like it should actually be generating this request body instead (Notice the extra ".member.1" after the "Dimensions" string):

Action=PutMetricData
&Namespace=MyMetricTest
&MetricData.member.1.MetricName=MyMetricName
&MetricData.member.1.Dimensions.member.1.Name=MyDimensionName
&MetricData.member.1.Dimensions.member.1.Value=MyDimensionValue
&MetricData.member.1.Value=100
&Version=2010-08-01

Here is a code snippet to fully reproduce the issue:

#include <iostream>

#include "aws/core/auth/AWSCredentialsProvider.h"
#include "aws/monitoring/CloudWatchClient.h"
#include "aws/monitoring/model/PutMetricDataRequest.h"

using namespace Aws;
using namespace Aws::Auth;
using namespace Aws::CloudWatch;
using namespace Aws::CloudWatch::Model;
using namespace Aws::Http;
using namespace Aws::Client;
using namespace std::chrono;

int main()
{
    /*
    This code results in the following output:

    ERROR: MalformedInput::Unable to parse ExceptionName: MalformedInput Message: Unexpected complex element termination
    Transmission failure
    */

    const char* accessKey = "MY_ACCESS_KEY";
    const char* secretKey = "MY_SECRET_KEY";

    AWSCredentials basicCreds(accessKey, secretKey);
    CloudWatchClient client = CloudWatchClient(basicCreds);
    PutMetricDataRequest request;
    request.SetNamespace("MyMetricTest");

    MetricDatum datum;
    datum.SetMetricName("MyMetricName");
    datum.SetValue(100.0);

    Dimension dim;
    dim.SetName("MyDimensionName");
    dim.SetValue("MyDimensionValue");

    //This line is the problem!
    datum.AddDimensions(dim);

    Aws::Vector<MetricDatum> metrics;
    metrics.push_back(datum);
    request.SetMetricData(metrics);

    char requestDump[4096];
    request.GetBody()->getline(requestDump,4096);
    std::cout << "REQUEST = " << requestDump << std::endl;

    PutMetricDataOutcome outcome = client.PutMetricData(request);
    if (!outcome.IsSuccess())
    {
        std::cout << "ERROR: " << outcome.GetError().GetExceptionName() << "::" << outcome.GetError().GetMessage() << std::endl;
    }
    std::cout << "Transmission " << (outcome.IsSuccess() ? "success" : "failure") << std::endl;

    char dummy[256];
    std::cin.getline(dummy, 256);
}

[JonathanHenson]

We'll have to update the generator. Thanks for letting us know.

[kevincdeng]

Please fix this soon, it makes the CW client unusable without patching the SDK source.

[JonathanHenson]

looking in to it now.

[kevincdeng]

This is the patch I'm using, in case it's any help

--- /Users/chaodeng/MetricDatum.cpp 2016-02-11 13:22:37.000000000 -0800
+++ /Users/chaodeng/MetricDatum.cpp.2 2016-02-11 13:30:36.000000000 -0800
@@ -107,10 +107,11 @@
   }
   if(m_dimensionsHasBeenSet)
   {
+      size_t i = 1;
       for(auto& item : m_dimensions)
       {
         Aws::StringStream dimensionsSs;
-        dimensionsSs << location << index << locationValue << ".Dimensions";
+        dimensionsSs << location << index << locationValue << ".Dimensions.member." << std::to_string(i++);
         item.OutputToStream(oStream, dimensionsSs.str().c_str());
       }
   }
@@ -142,10 +143,12 @@
   }
   if(m_dimensionsHasBeenSet)
   {
+      size_t i = 1;
       for(auto& item : m_dimensions)
       {
         Aws::String locationAndListMember(location);
-        locationAndListMember += ".Dimensions";
+        locationAndListMember += ".Dimensions.member.";
+        locationAndListMember += std::to_string(i++);
         item.OutputToStream(oStream, locationAndListMember.c_str());
       }
   }

[JonathanHenson]

Ok, I just pushed. Can you give it a try?

[kevincdeng]

It works now. Thanks!