Feature request: support high resolution metrics

[dreamorosi]

Use case

Amazon CloudWatch announced support for high resolution metric extraction from structured logs (EMF). Customers can now provide an optional StorageResolution parameter within the EMF specification with a value of 1 or 60 (default) to indicate the desired resolution (in seconds) of the metric.

We should consider adding support for this new optional parameter to Metrics.

The EMF log should have this format:

{
  "_aws": {
    "CloudWatchMetrics": [
      {
        "Metrics": [
          {
            "Name": "Time",
            "Unit": "Milliseconds",
            "StorageResolution": 60 // <- new key
          }
        ],
        ...
      }
    ]
  },
  "Time": 1
}

As part of this issue we should also update the API docs, documentation, and unit/integration tests.

Solution/User Experience

Proposed DX:

using AWS.Lambda.Powertools.Metrics;

public class Function {

  [Metrics(Namespace = "ExampleApplication", Service = "Booking")]
  public async Task<APIGatewayProxyResponse> FunctionHandler(APIGatewayProxyRequest apigProxyEvent, ILambdaContext context)
  {
    // Publish a metric with standard resolution i.e. StorageResolution = 60
    Metrics.AddMetric("SuccessfulBooking", 1, MetricUnit.COUNT, MetricResolution.HIGH);
    // Publish a metric with high resolution i.e. StorageResolution = 1
    Metrics.AddMetric("FailedBooking", 1, MetricUnit.COUNT, MetricResolution.HIGH);
    // The last parameter (storage resolution) is optional
    Metrics.AddMetric("SuccessfulUpgrade", 1, MetricUnit.COUNT);
  }
}

To support the proposal, a new MetricResolution enum should be added, as well as changes to the Metrics.AddMetric method.

Alternative solutions

No response

Acknowledgment

• This feature request meets Lambda Powertools Tenets
• Should this be considered in other Lambda Powertools languages? i.e. Java, TypeScript