AWS.Lambda.Powertools.Metrics

AWS.Lambda.Powertools.Metrics

Metrics creates custom metrics asynchronously by logging metrics to standard output following Amazon CloudWatch Embedded Metric Format (EMF).

These metrics can be visualized through Amazon CloudWatch Console.

Key features

• Aggregate up to 100 metrics using a single CloudWatch EMF object (large JSON blob)
• Validate against common metric definitions mistakes (metric unit, values, max dimensions, max metrics, etc)
• Metrics are created asynchronously by CloudWatch service, no custom stacks needed
• Context manager to create a one off metric with a different dimension

Read the docs

For a full list of features go to docs.powertools.aws.dev/lambda/dotnet/core/metrics/

GitHub: https://github.com/aws-powertools/powertools-lambda-dotnet/

Sample Function

View the full example here: https://github.com/aws-powertools/powertools-lambda-dotnet/tree/develop/examples/Metrics

public class Function
{
    /// <summary>
    /// Lambda Handler
    /// </summary>
    /// <param name="apigwProxyEvent">API Gateway Proxy event</param>
    /// <param name="context">AWS Lambda context</param>
    /// <returns>API Gateway Proxy response</returns>
    [Logging(LogEvent = true)]
    [Metrics(CaptureColdStart = true)]
    public async Task<APIGatewayProxyResponse> FunctionHandler(APIGatewayProxyRequest apigwProxyEvent,
        ILambdaContext context)
    {
        var requestContextRequestId = apigwProxyEvent.RequestContext.RequestId;

        Logger.LogInformation("Getting ip address from external service");

        // Add Metric to capture the amount of time 
        Metrics.PushSingleMetric(
            metricName: "CallingIP",
            value: 1,
            unit: MetricUnit.Count,
            service: "lambda-powertools-metrics-example",
            defaultDimensions: new Dictionary<string, string>
            {
                { "Metric Type", "Single" }
            });
        
        var watch = Stopwatch.StartNew();
        var location = await GetCallingIp();
        watch.Stop();
        
        Metrics.AddMetric("ElapsedExecutionTime", watch.ElapsedMilliseconds, MetricUnit.Milliseconds);
        Metrics.AddMetric("SuccessfulLocations", 1, MetricUnit.Count);
        
        var lookupRecord = new LookupRecord(lookupId: requestContextRequestId,
            greeting: "Hello Powertools for AWS Lambda (.NET)", ipAddress: location);

        try
        {
            Metrics.PushSingleMetric(
                metricName: "RecordsSaved",
                value: 1,
                unit: MetricUnit.Count,
                service: "lambda-powertools-metrics-example",
                defaultDimensions: new Dictionary<string, string>
                {
                    { "Metric Type", "Single" }
                });
            
            await SaveRecordInDynamo(lookupRecord);
            
            Metrics.AddMetric("SuccessfulWrites", 1, MetricUnit.Count);
            
            return new APIGatewayProxyResponse
            {
                Body = JsonSerializer.Serialize(lookupRecord),
                StatusCode = 200,
                Headers = new Dictionary<string, string> { { "Content-Type", "application/json" } }
            };
        }
        catch (Exception e)
        {
            Logger.LogError(e.Message);
            
            return new APIGatewayProxyResponse
            {
                Body = e.Message,
                StatusCode = 500,
                Headers = new Dictionary<string, string> { { "Content-Type", "application/json" } }
            };
        }
    }
}

Sample output

{
    "_aws": {
        "Timestamp": 1648181318790,
        "CloudWatchMetrics": [
            {
                "Namespace": "AWSLambdaPowertools",
                "Metrics": [
                    {
                        "Name": "CallingIP",
                        "Unit": "Count"
                    }
                ],
                "Dimensions": [
                    [
                        "Metric Type"
                    ],
                    [
                        "Service"
                    ]
                ]
            }
        ]
    },
    "Metric Type": "Single",
    "Service": "lambda-powertools-metrics-example",
    "CallingIP": 1
}