Allow set custom timestamp for metric datapoint

[PatrykMilewski]

Expected Behavior

When I'm sending datapoint with sendDistributionMetric function, I would like to specify my custom timestamp.

Actual Behavior

Right now it automatically uses the actual time for timestamp generation.

Specifications

• Datadog Lambda Layer version: none, datadog-lambda-layer-js:2.17.0
• Node version: 12.x

[agocs]

👋 Hi, I've added this to a list of feature requests. Custom timestamps in this library make sense. We already allow them in Ruby, Python, and Go.

[PatrykMilewski]

@agocs Could you specify the header of the function, that would have this feature? I'm not sure how you are planning your API for this package, but if you guys would give me some hints, then I could implement it myself and create PR.

[agocs]

Hey @PatrykMilewski , I definitely appreciate the offer. I think the new function would take the signature

export function sendDistributionMetricWithDate(name: string, value: number, date: Date, ...tags: string[])

It would, unfortunately, require refactoring listener.sendDistrobutionMetric and a few other functions to accept the custom date.

[vishnuvisnu]

public sendDistributionMetricWithDate(name: string, value: number, date: Date, ...tags: string[])  {

   if (this.config.logForwarding) {
     writeMetricToStdout(name, value, tags);
     return;
   }
   const dist = new Distribution(name, [{ timestamp: date, value }], ...tags);
   if (this.currentProcessor !== undefined) {
     this.currentProcessor.then((processor) => {
       processor.addMetric(dist);
     });
   } else {
     logError("can't send metrics, datadog lambda handler not set up.");
   }
}
public sendDistributionMetric(name: string, value: number, ...tags: string[]) {
 sendDistributionMetricWithDate(name, value, new Date(), tags);
}

These changes to MetricListener in listener.ts along with new function sendDistributionMetricWithDate in index.ts should work, right?

[vishnuvisnu]

@agocs Created PR #63 to add custom timestamp.

[vishnuvisnu]

@agocs Could you please expedite PR? We are currently using in datadog in production and using the datadog metrics from cloudwatch logs (that were published from the segment) that are in forming like MONITORING|..|..|..|.. but there is significant delay in getting metrics in datadog. This is the current ticket with the datadog team https://help.datadoghq.com/hc/en-us/requests/322610?flash_digest=9f923b6f7becc24b49af9543c88c5faa51c3a52c.

Thanks.

[DarcyRaynerDD]

Hey @vishnuvisnu, thanks for the PR. I can review this for you.

[PatrykMilewski]

I'm closing it since PR #63 is already merged into master. Thank you @vishnuvisnu