client-cloudwatch not taking milliseconds since 1970

[codermpl]

Checkboxes for prior research

• I've gone through Developer Guide and API reference
• I've checked AWS Forums and StackOverflow.
• I've searched for previous similar issues and didn't find any solution.

Describe the bug

client-cloudwatch MetricDatum interface says.

    /**
     * <p>The time the metric data was received, expressed as the number of milliseconds
     *             since Jan 1, 1970 00:00:00 UTC.</p>
     * @public
     */
    Timestamp?: Date | undefined;

This seems to be conflicting. The comment says it should take number of ms, but the type signature says it should take a Date object. API documentation confirms it's supposed to take ms since 1970: https://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/API_MetricDatum.html

I'd be happy if it could take either Date or ms as a number. But seems like it should at least take ms since that's what the API spec says.

Regression Issue

• Select this option if this issue appears to be a regression.

SDK version number

"@aws-sdk/client-cloudwatch": "^3.734.0",

Which JavaScript Runtime is this issue in?

Node.js

Details of the browser/Node.js/ReactNative version

22

Reproduction Steps

Pass a number in Timestamp field for PutMetricData

Observed Behavior

Fails

Expected Behavior

Timestamp property accepts ms since 1970

Possible Solution

Allow passing either a Date or number to the Timestamp property.

Additional Information/Context

No response

[aBurmeseDev]

Hi @codermpl - thanks for reaching out.

Which SDK language are you using and are you running into any issue? Could you share your code snippet along with the error if any?

[codermpl]

language is typescript

[codermpl]

code example:

  const input: PutMetricDataInput = {
    Namespace: 'abc',
    MetricData: [{ MetricName: 'name', Timestamp: Date.now() }],
  };

Type 'number' is not assignable to type 'Date'.ts(2322)

[aBurmeseDev]

Date.now() returns a number where Timestamp expects Date object. Try this:

const input: PutMetricDataInput = {
    Namespace: 'abc',
    MetricData: [{ 
        MetricName: 'name', 
        Timestamp: new Date() // Convert to Date object or alternative new Date(Date.now()) 
    }],
};

[codermpl]

Yes, that's the bug. It expects a Date, but it's supposed to expect a number.

* <p>The time the metric data was received, expressed as the number of milliseconds
 *             since Jan 1, 1970 00:00:00 UTC.</p>

[aBurmeseDev]

Based on the service model, it expects Date and I reached out to service team to confirm. It may be the docs that causes confusion. I'll circle back when I hear back from service team.