Cognito C++ SDK, Broken Pipe

Question

I have an issue when invoking Cognito Admin API calls with C++ SDK both from Lambda and from an external client. I am using the the AWS C++ SDK Version 1.11.75, but have experiences this with previous versions too.

Approximately, 1 in 5 requests (eg AdminUpdateUserAttributes) the API call crashes with a broken pipe.

A typical request (this one executed from a Cognito Post Login Trigger), looks like this:

Aws::CognitoIdentityProvider::Model::AdminUpdateUserAttributesRequest request;
request.SetUsername(username);
request.SetUserPoolId(user_pool_id);
request.SetUserAttributes({Aws::CognitoIdentityProvider::Model::AttributeType().WithName("custom:client_queue").WithValue(queue_url)});

auto outcome{m_idp_client.AdminUpdateUserAttributes(request)};
...

The SDK is initialized just with default options and Identity Provider Client is default constructed.

Has anyone any ideas how to make this more reliable?

Answer

I have had this question also posted on the Github for the C++ SDK, Sergey has provided a solution:

> Could you please check if setting Aws::SDKOptions.httpOptions.installSigPipeHandler option will fix your issue?
> 
>   Aws::SDKOptions options;
>     options.httpOptions.installSigPipeHandler = true;
> 
> Also, from https://docs.aws.amazon.com/sdk-for-cpp/v1/developer-guide/basic-use.html#sdk-setting-options:
> 
>     When installSigPipeHandler is true, the SDK for C++ uses a handler that ignores SIGPIPE signals. For more information on SIGPIPE, see Operation Error 
> Signals on the GNU Operating System website. For more information on the curl handler, see CURLOPT_NOSIGNAL explained on the curl website.
> 
>     The underlying libraries of curl and OpenSSL can send a SIGPIPE signal to notify when the remote side closes a connection. These signals must be handled > by the application. For more information this curl functionality, see libcurl thread safety
>     on the curl website. This behavior is not automatically built-in to the SDK because signal handlers are global for each application and the library is a 
> dependency for the SDK.
> 
> Best regards,
> Sergey
 
And the github discussion in it is:
[
https://github.com/aws/aws-sdk-cpp/discussions/2494](https://github.com/aws/aws-sdk-cpp/discussions/2494)

Cognito C++ SDK, Broken Pipe

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