Can SdkErrors implement conversion to ServiceError or aws_sdk_s3::Error by reference and not value (move)?

[jrcavani]

I'm implementing a simple flow of getting an object, and checking its errors - if it's a NoSuchKey, we log it one way and do something, and if it's a different variant, we log and do some other thing.

I'm having a hard time doing this beyond the suggested way (went through a few discussions/issues/Google searches):

    pub async fn get_object(&self, bucket: &str, key: &str) -> Result<Bytes> {
        let resp = self
            .client
            .get_object()
            .bucket(bucket)
            .key(key)
            .send()
            .await;
        let resp = match resp.map_err(|e| aws_sdk_s3::Error::from(e)) {
            Ok(resp) => Ok(resp),
            Err(aws_sdk_s3::Error::NoSuchKey(e)) => {
                warn!(
                    "Failed to get s3://{}/{}: {} (NoSuchKey). Skipping.",
                    bucket, key, e
                );
                Err(aws_sdk_s3::Error::NoSuchKey(e))
            }
            Err(e) => {
                warn!("Failed to get s3://{}/{}. Other error.", bucket, key);
                Err(e)
            }
        }?;

        let content = resp.body.collect().await?.into_bytes();
        anyhow::Ok(content)
    }

This works. However, sometimes I don't want to consume the resp. I would like to be able to take a reference of resp: Result<GetObjectOutput, SdkError<...,...>> and do error parsing without worrying about moving or reconstructing the resp.

    pub async fn get_object(&self, bucket: &str, key: &str) -> Result<Bytes> {
        let resp = self
            .client
            .get_object()
            .bucket(bucket)
            .key(key)
            .send()
            .await;
        match &resp.map_err(|e| aws_sdk_s3::Error::from(e)) {
            Err(aws_sdk_s3::Error::NoSuchKey(_)) => {
                warn!(
                    "Failed to get s3://{}/{}: (NoSuchKey). Skipping.",
                    bucket, key
                );
            }
            _ => {}
        };
        let resp = resp?;

        let content = resp.body.collect().await?.into_bytes();
        anyhow::Ok(content)
    }

The SdkError is not clone-able. It's into_service_error() also moves.

[jrcavani]

Oh I get it. So close...

    pub async fn get_object(&self, bucket: &str, key: &str) -> Result<Bytes> {
        let resp = self
            .client
            .get_object()
            .bucket(bucket)
            .key(key)
            .send()
            .await
            .map_err(aws_sdk_s3::Error::from);
        match &resp {
            Err(aws_sdk_s3::Error::NoSuchKey(_)) => {
                warn!(
                    "Failed to get s3://{}/{}: (NoSuchKey). Skipping.",
                    bucket, key
                );
            }
            _ => {}
        };
        let resp = resp?;

        let content = resp.body.collect().await?.into_bytes();
        anyhow::Ok(content)
    }

[jrcavani]

I'm here again... How do I catch 429 TooManyRequests?

After mapping to aws_sdk_s3::Error, it is variant Unhandled. To my surprise, the content, like .meta(), .code(), or .message() are all empty.

{:#} meta {:?} message {:?}

gives

unhandled error meta ErrorMetadata { code: None, message: None, extras: None }

[jrcavani]

How come aws-sdk-lambda has this https://docs.rs/aws-sdk-lambda/latest/aws_sdk_lambda/enum.Error.html#variant.TooManyRequestsException error variant, but S3 doesn't... Really need this to do infinite retries on some operations, and I'm currently getting by by catching all Unhandled.

[jdisanti]

In the worst case, you can fall back onto the raw_response() method on SdkError: https://docs.rs/aws-smithy-runtime-api/1.1.1/aws_smithy_runtime_api/client/result/enum.SdkError.html#method.raw_response

I don't know for sure, but my best guess is that S3 is responding with HTTP status 429 without a response body, so it doesn't turn into a modeled error, and that's why the meta/code/message fields are not populated.

[rcoh]

It seems like we need .as_service_error() -> Option<&E> to make it easier to check these things

[jrcavani]

Yeah I would like that. Otherwise I need to define my own errors to have more flexibility.

[rcoh]

this is done! Check out https://docs.rs/aws-smithy-runtime-api/latest/aws_smithy_runtime_api/client/result/enum.SdkError.html#method.as_service_error