Events are not sent in AWS Lambda

I have discovered some issues when using SDK on AWS Lambda/API Gateway

The following message is logged to sentry

[HttpGet("/health")]
[ProducesResponseType((int) HttpStatusCode.OK)]
public async Task HealthCheck()
{
    _logger.LogCritical("test");
    await Task.Delay(TimeSpan.FromSeconds(10));
}

while this does not

[HttpGet("/health")]
[ProducesResponseType((int) HttpStatusCode.OK)]
public IActionResult HealthCheck()
{
    _logger.LogCritical("test");
    return Ok()
}

The problem might be related to https://github.com/aws/aws-lambda-dotnet/issues/239. The thread is killed right after the response is sent.

[madmox]

Final note regarding the middleware: you should use context.Response.OnCompleted instead of flushing after await this._next(context);, otherwise you might miss any event logged after the middleware returns - e.g. middlewares higher in the ASP.NET pipeline, or any error logged by the lambda integration when marshalling the response to API gateway:

public class SentryEventsFlusherMiddleware
{
    private readonly RequestDelegate _next;

    public SentryEventsFlusherMiddleware(RequestDelegate next)
    {
        this._next = next;
    }

    public async Task InvokeAsync(HttpContext context, ISentryClient sentryClient)
    {
        context.Response.OnCompleted(async () =>
        {
            await sentryClient.FlushAsync(timeout: TimeSpan.FromSeconds(10));
        });

        await this._next(context);
    }
}

For non-ASP.NET lambdas, I ended up writing a basic try/catch/finally block in the function:

public class Function
{
    private readonly ILogger _logger;
    private readonly ISentryClient _sentryClient;

    public Function()
    {
        // Initialize dependency injection, configure services & logging...
    }

    public async Task ProcessSQSEvent(SQSEvent sqsEvent)
    {
        try
        {
            // Your code
        }
        catch (Exception ex)
        {
            this._logger.LogError(ex, ex.Message);
            throw; // Let AWS move SQS messages to deadletter
        }
        finally
        {
            await this._sentryClient.FlushAsync(timeout: TimeSpan.FromSeconds(10));
        }
    }
}

This all worked for me with 2.0.0-beta4.

[bruno-garcia]

I’d suggest using 2.0.0-beta4. The only reason it’s not 2.0.0 (non preview) is that I want to fit some more “breaking” changes in it before but we’re currently busy with a Android SDK so this is on hold.