AWS.Lambda.Powertools.Tracing

AWS.Lambda.Powertools.Tracing

Powertools for AWS Lambda (.NET) tracing is an opinionated thin wrapper for AWS X-Ray .NET SDK a provides functionality to reduce the overhead of performing common tracing tasks.

Key Features

• Helper methods to improve the developer experience for creating custom AWS X-Ray subsegments.
• Capture cold start as annotation.
• Capture function responses and full exceptions as metadata.
• Better experience when developing with multiple threads.
• Auto-patch supported modules by AWS X-Ray

Read the docs

For a full list of features go to docs.aws.amazon.com/powertools/dotnet/core/tracing/

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/Tracing

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)]
    [Tracing(CaptureMode = TracingCaptureMode.ResponseAndError)]
    public async Task<APIGatewayProxyResponse> FunctionHandler(APIGatewayProxyRequest apigwProxyEvent,
        ILambdaContext context)
    {
        var requestContextRequestId = apigwProxyEvent.RequestContext.RequestId;

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

        var location = await GetCallingIp().ConfigureAwait(false);

        var lookupRecord = new LookupRecord(lookupId: requestContextRequestId,
            greeting: "Hello Powertools for AWS Lambda (.NET)", ipAddress: location);

        // Trace Fluent API
        Tracing.WithSubsegment("LoggingResponse",
            subsegment =>
            {
                subsegment.AddAnnotation("AccountId", apigwProxyEvent.RequestContext.AccountId);
                subsegment.AddMetadata("LookupRecord", lookupRecord);
            });

        try
        {
            await SaveRecordInDynamo(lookupRecord);

            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" } }
            };
        }
    }

    /// <summary>
    /// Calls location api to return IP address
    /// </summary>
    /// <returns>IP address string</returns>
    [Tracing(SegmentName = "Location service")]
    private static async Task<string?> GetCallingIp()
    {
        if (_httpClient == null) return "0.0.0.0";
        _httpClient.DefaultRequestHeaders.Accept.Clear();
        _httpClient.DefaultRequestHeaders.Add("User-Agent", "AWS Lambda .Net Client");

        try
        {
            Logger.LogInformation("Calling Check IP API");

            var response = await _httpClient.GetStringAsync("https://checkip.amazonaws.com/").ConfigureAwait(false);
            var ip = response.Replace("\n", "");

            Logger.LogInformation($"API response returned {ip}");

            return ip;
        }
        catch (Exception ex)
        {
            Logger.LogError(ex);
            throw;
        }
    }

    /// <summary>
    /// Saves the lookup record in DynamoDB
    /// </summary>
    /// <param name="lookupRecord">Instance of LookupRecord</param>
    /// <returns>A Task that can be used to poll or wait for results, or both.</returns>
    [Tracing(SegmentName = "DynamoDB")]
    private static async Task SaveRecordInDynamo(LookupRecord lookupRecord)
    {
        try
        {
            Logger.LogInformation($"Saving record with id {lookupRecord.LookupId}");
            await _dynamoDbContext?.SaveAsync(lookupRecord)!;
        }
        catch (AmazonDynamoDBException e)
        {
            Logger.LogCritical(e.Message);
            throw;
        }
    }
}

Sample output