Adding timestamps to metrics in PutMetricDataRequest results in a MalformedInput exception

When constructing a MetricDatum for CloudWatch, it seems that setting the timestamp on any datum in the request 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.Timestamp=1.44409e+012
&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 (the timestamp is required to be ISO 8601 formatted):

Action=PutMetricData
&Namespace=MyMetricTest
&MetricData.member.1.MetricName=MyMetricName
&MetricData.member.1.Timestamp=2015-10-05T16:40:00Z
&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;

long long GetMillisSinceEpoch(const std::chrono::time_point<std::chrono::system_clock>& timePoint)
{
    return duration_cast<std::chrono::milliseconds>(timePoint.time_since_epoch()).count();
}

long long GetMillisSinceEpoch()
{
    return GetMillisSinceEpoch(system_clock::now());
}

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

    ERROR: MalformedInput::Unable to parse ExceptionName: MalformedInput Message: timestamp must follow ISO8601
    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);

    //This line is the problem!
    //(it's also not clear from the documentation what this "double" value actually represents)
    datum.SetTimestamp(static_cast<double>(GetMillisSinceEpoch())); 

    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]

timestamps are usually seconds.milliseconds for Amazon timestamps. Let me check the docs.

for now, you can use:

double Aws::Utils::DateTime::ComputeCurrentTimestampInAmazonFormat()

[JonathanHenson]

According to this: https://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/API_MetricDatum.html

the timestamp is in ISO format. Which means the request is modeled wrong. We'll have to do something different for CloudWatch. Try the double format I mentioned earlier since seconds.milliseconds is supposed to convert to java DateTime easily (maybe it will work).

Unfortunately, the only interface I have for setting the timestamp on a MetricDatum is via the "SetTimestamp" function which only takes a double as a parameter. That doesn't give me much control over the formatting. I tried passing in seconds and milliseconds, but they both give the same error.

If you look at:

https://github.com/awslabs/aws-sdk-cpp/blob/master/aws-cpp-sdk-monitoring/source/model/MetricDatum.cpp

I think the issue is on lines 121:

oStream << location << index << locationValue << ".Timestamp=" << m_timestamp << "&";

`And line 156:

oStream << location << ".Timestamp=" << m_timestamp << "&";

In both cases, the value of m_timestamp (a double) is written to the output stream with no formatting applied and no string conversion done.

[JonathanHenson]

We'll have to update the generator to handle this and then export the newly generated client. Thanks for reporting this problem.

[JonathanHenson]

I've updated this one so that timestamp fields are a string. Then I added

DateTime::ComputeTimestampAsISO8601Format()

You can use this to populate the field. I'll be pushing it up to github in the next few days.

[JonathanHenson]

Just pushed, can you give it a try.