Implement errors.Unwrap for awserr.Error

[TennyZhuang]

Feature description

awserr.Error implement a method called Orig(), It's exactly same as errors.Unwrap defined in errors from go1.13. It's better to keep consistent with standard library.

[paxan]

We utilize context.WithTimeout(...) combined with various AWS Go SDK ...WithContext methods.

Because errors in our code may be wrapped, we use errors.Is to detect that a context deadline was exceeded:

if errors.Is(err, context.DeadlineExceeded) { ... }

Unfortunately, errors produced by awserr do not play well with the standard errors.Unwrap. We've ran into subtle bugs in our "deadline exceeds" logic. I resorted to doing stuff like this as a workaround:

c := make(chan error)
ctx, cancel := context.WithTimeout(ctx, 5*time.Minute)
defer cancel()

// move the cancellable logic into a goro!
go func() {
	defer close(c)
	if err := DoAWSThing1(ctx, ...); err != nil {
		c <- err
		return
	}
	if err := DoAWSThing2(ctx, ...); err != nil {
		c <- err
		return
	}
	if err := DoAWSThing3(ctx, ...); err != nil {
		c <- err
		return
	}
}()

select {
case <-ctx.Done():
	return ctx.Err()
case err := <-c:
	// extra defence against awserr.Error-s that bury
	// context deadline error in OrigErr :(
	if ctxerr := ctx.Err(); ctxerr != nil {
		return ctxerr
	}
	return err
}

[migueleliasweb]

if ctxerr := ctx.Err(); ctxerr != nil {
		return ctxerr
	}
	return err

OMG I'm having this exact problem. The errors returned are impossible to be checked using errors.Is() which makes VERY HARD to react to specific errors in the code.

I will definitely try your workaround @paxan ! Thanks for the idea!

[skotambkar]

The aws/aws-sdk-go-v2 uses errors.Unwrap. We do not have plans to support this in V1 SDK. Please take a look at the v2 sdk.

[github-actions]

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[nolotz]

The aws/aws-sdk-go-v2 uses errors.Unwrap. We do not have plans to support this in V1 SDK. Please take a look at the v2 sdk.

Hi @skotambkar

Any chance to get it supported with a merge request like #4010? We have issues updating to v2 left alone that there are things that aren't even supported like DAX.