CloudWatch.PutMetricData - Issue with StatisticSet & Value

[jitcompile]

StatisticValues and Value are mutually exclusive when trying the PutMetricData of cloudwatch. I've tried the following and all the 4 attempts have failed with the same exception:-

• StatisticValues are set and Value is not set
• StatisticValues are set and Value is set to aws.Float64(0)
• StatisticValues are set and Value is set to aws.Float64(null) where null is initialized as below
  • var null float64 (since go zero values it, its same as previous attempt)
• StatisticValues are set and Value is explicitly set to nil

In all the above cases, I receive the same exception

InvalidParameterCombination: The parameters MetricData.member.1.Value and MetricData.member.1.StatisticValues are mutually exclusive and you have specified both.

This is a code migration from .Net to golang. In .net sdk, I used to set the Value field to default(double) and it worked.

Here's the go code

    client := cloudwatch.New(a.config)
    input := cloudwatch.PutMetricDataInput{}
    input.Namespace = aws.String("test")

    instanceNameDimension := cloudwatch.Dimension{Name: aws.String("InstanceName"), Value: aws.String("i-abcd")}

    for _, stat := range stats {
        datum := cloudwatch.MetricDatum{MetricName: aws.String(stat.Name), Timestamp: aws.Time(stat.Timestamp), Unit: aws.String(stat.Unit)}
        datum.Dimensions = append(datum.Dimensions, &runIDDimension)
        datum.StatisticValues = &cloudwatch.StatisticSet{Maximum: aws.Float64(stat.Maximum), Minimum: aws.Float64(stat.Minimum), SampleCount: aws.Float64(stat.SampleCount), Sum: aws.Float64(stat.Sum)}
        input.MetricData = append(input.MetricData, &datum)
    }
    _, err := client.PutMetricData(&input)

[jasdel]

Hi @jitcompile I'm having a little difficulty reproducing the issue you're encountering. The following example based on your above code is able to report metrics correctly to CloudWatch. Are you able to reproduce your issue using this example? Leaving the Value field unset (nil) should be the correct action.

package main

import (
    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/service/cloudwatch"
    "log"
    "time"
)

type Stat struct {
    Name, Unit                         string
    Timestamp                          time.Time
    Minimum, Maximum, SampleCount, Sum float64
}

var stats = []Stat{
    {"Name", "Seconds", time.Now().Add(-1 * time.Second), 0, 5, 10, 100},
    {"Name", "Seconds", time.Now().Add(-2 * time.Second), 1, 5, 10, 100},
    {"Name", "Seconds", time.Now().Add(-3 * time.Second), 2, 5, 10, 100},
    {"Name", "Seconds", time.Now().Add(-3 * time.Second), 3, 5, 10, 100},
    {"Name", "Seconds", time.Now().Add(-4 * time.Second), 4, 6, 10, 100},
    {"Name", "Seconds", time.Now().Add(-5 * time.Second), 5, 7, 10, 100},
    {"Name", "Seconds", time.Now().Add(-6 * time.Second), 6, 8, 10, 100},
    {"Name", "Seconds", time.Now().Add(-7 * time.Second), 6, 9, 10, 100},
}

var runIDDimension = cloudwatch.Dimension{
    Name:  aws.String("DimName"),
    Value: aws.String("i-dcba"),
}

func main() {
    client := cloudwatch.New(nil)
    input := cloudwatch.PutMetricDataInput{}
    input.Namespace = aws.String("test")

    instanceNameDimension := cloudwatch.Dimension{
        Name:  aws.String("InstanceName"),
        Value: aws.String("i-abcd"),
    }

    for _, stat := range stats {
        datum := cloudwatch.MetricDatum{
            MetricName: aws.String(stat.Name),
            Timestamp:  aws.Time(stat.Timestamp),
            Unit:       aws.String(stat.Unit),
        }
        datum.Dimensions = append(datum.Dimensions, &instanceNameDimension)
        datum.StatisticValues = &cloudwatch.StatisticSet{
            Maximum:     aws.Float64(stat.Maximum),
            Minimum:     aws.Float64(stat.Minimum),
            SampleCount: aws.Float64(stat.SampleCount),
            Sum:         aws.Float64(stat.Sum),
        }
        input.MetricData = append(input.MetricData, &datum)
    }
    _, err := client.PutMetricData(&input)
    if err != nil {
        log.Fatalln(err)
    }
}

I suggest updating your config to print out wire logs of requests. With that we'll be able to see what the SDK is sending. You can use the following options to enable logging.

client := cloudwatch.New(aws.NewConfig().WithLogLevel(aws.LogDebugWithHTTPBody))
...

[jitcompile]

I updated the version of sdk from 0.7.0 to 0.7.1 and it seems to work. Weird. Also it could be a combination of issues due to for-range and pointer of values. I've updated to 0.7.1 and using aws.String implementation, it works as expected. Thanks. I'm closing the issue.