What's the recommended way to append a string to the user-agent?

[koren-eli]

Hi,

Our use case requires appending a custom suffix to the existing user agent string so that we can identify S3 requests in our logs.

One option I found is setting

ClientAppId = "customString"

in AmazonS3Config, but that adds the identifier as app/customString in the header.

Is there any supported method in the SDK to append a plain suffix (without app/) to the default user agent, similar to how other AWS SDKs expose user-agent append mechanisms?

[normj]

By suffix do you need your custom value at the end of the user agent or just looking to a string literal somewhere in the user agent without the SDK adding anything like app/?

[koren-eli]

just looking to a string literal somewhere in the user agent without the SDK adding anything like app/

This. It doesn't have to be at the end of the user agent.

[ashishdhingra]

The ClientAppId setting in .NET SDK corresponds to about Application ID. This is a standard way to send user agent which is prefixed by app/ and cannot/should be changed.

I do see that AWS Java SDK v2 does support setting user agent prefix and suffix. The below example:

package org.example;

import software.amazon.awssdk.core.client.config.ClientOverrideConfiguration;
import software.amazon.awssdk.core.client.config.SdkAdvancedClientOption;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.model.Bucket;
import software.amazon.awssdk.services.s3.model.ListBucketsResponse;
import software.amazon.awssdk.services.s3.model.S3Exception;
import java.util.List;

public class HelloS3 {
    public static void main(String[] args) {
        String customUserAgentPrefix = "PREFIX-MyCustomApp/1.0";
        String customUserAgentSuffix = "SUFFIX-MyCustomApp/1.0";

        // Create a ClientOverrideConfiguration with the custom user agent prefix and suffix
        ClientOverrideConfiguration overrideConfig = ClientOverrideConfiguration.builder()
                .putAdvancedOption(SdkAdvancedClientOption.USER_AGENT_PREFIX, customUserAgentPrefix)
                .putAdvancedOption(SdkAdvancedClientOption.USER_AGENT_SUFFIX, customUserAgentSuffix)
                .build();
        Region region = Region.US_EAST_1;
        S3Client s3 = S3Client.builder()
                .region(region)
                .overrideConfiguration(overrideConfig)
                .build();

        listBuckets(s3);
    }

    public static void listBuckets(S3Client s3) {
        try {
            ListBucketsResponse response = s3.listBuckets();
            List<Bucket> bucketList = response.buckets();
            bucketList.forEach(bucket -> {
                System.out.println("Bucket Name: " + bucket.name());
            });

        } catch (S3Exception e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }
}

This emits the below user agent header:

User-Agent: PREFIX-MyCustomApp/1.0 aws-sdk-java/2.35.10 md/io#sync md/http#Apache ua/2.1 api/S3#2.35.x os/Windows_11#10.0 lang/java#25 md/OpenJDK_64-Bit_Server_VM#25+36-LTS md/vendor#Amazon.com_Inc. md/en_US m/D,G,v,w SUFFIX-MyCustomApp/1.0

This is something not supported out of the box in AWS SDK for .NET. Need to review this with the team.

Thanks,
Ashish

[koren-eli]

It seems to be supported by most AWS SDKs:

Go:

import (
    "github.com/aws/aws-sdk-go-v2/config"    
)

client := s3.NewFromConfig(awsCfg, func(options *s3.Options) {
    options.APIOptions = append(options.APIOptions, middleware2.AddUserAgentKey("custom_string"))
})

boto3:

import boto3
from botocore.config import Config

# Configure custom retry and timeout settings
cfg = Config(
   user_agent_extra = "custom_string",
)

C++:

Aws::Client::ClientConfiguration clientConfig;
clientConfig.userAgent = Aws::Client::ComputeUserAgentString() + " custom_string";

Thank you for considering adding this to the .NET SDK as well.

[normj]

There is a back door way in the .NET SDK for modifying the user agent string. Keep in mind you using APIs from our SDK's "Internal" namespace where we don't guarantee backwards compatibility. The "Internal" namespaces we generally put APIs to share with service packages but not necessarily end users. I don't see us changing these APIs anytime soon but want to be clear their is the possibility so code defensively or take note that are using APIs that don't guarantee backwards compatibility.

var ddbClient = new Amazon.DynamoDBv2.AmazonDynamoDBClient();
ddbClient.BeforeRequestEvent += ServiceClientBeforeRequestEvent;

void ServiceClientBeforeRequestEvent(object sender, RequestEventArgs e)
{
    var userAgentString = "customString";
    var args = e as Amazon.Runtime.WebServiceRequestEventArgs;
    if (args == null)
        return;

    ((Amazon.Runtime.Internal.IAmazonWebServiceRequest)args.Request).UserAgentDetails.AddUserAgentComponent(userAgentString);
}

[koren-eli]

Thanks for posting the backdoor. I tested it and verified it’s working. I’ll keep this discussion open while waiting for the team’s response about supporting it through a public interface.