Configure AWS CRT-based HTTP clients - AWS SDK for Java 2.x
Access the AWS CRT-based HTTP clientsUse and configure an AWS CRT-based HTTP clientSet an AWS CRT-based HTTP client as the defaultAdvanced configurationHTTP/2 supportProxy configuration example

Configure AWS CRT-based HTTP clients

The AWS CRT-based HTTP clients include the synchronous AwsCrtHttpClient and asynchronous AwsCrtAsyncHttpClient. The AWS CRT-based HTTP clients provide the following HTTP client benefits:

  • Faster SDK startup time

  • Smaller memory footprint

  • Reduced latency time

  • Connection health management

  • DNS load balancing

AWS CRT-based components in the SDK

The AWS CRT-based HTTP clients, described in this topic, and the AWS CRT-based S3 client are different components in the SDK.

The synchronous and asynchronous AWS CRT-based HTTP clients are implementations SDK HTTP client interfaces and are used for general HTTP communication. They are alternatives to the other synchronous or asynchronous HTTP clients in the SDK with additional benefits.

The AWS CRT-based S3 client is an implementation of the S3AsyncClient interface and is used for working with the Amazon S3 service. It is an alternative to the Java-based implementation of the S3AsyncClient interface and offers several advantages.

Although both components use libraries from the AWS Common Runtime, the AWS CRT-based HTTP clients do not use the aws-c-s3 library and do not support the S3 multipart upload API features. The AWS CRT-based S3 client, by contrast, was purpose-built to support the S3 multipart upload API features.

Access the AWS CRT-based HTTP clients

Before you can use the AWS CRT-based HTTP clients, add the aws-crt-client artifact with a minimum version of 2.22.0 to your project's dependencies.

The following Maven pom.xml shows the AWS CRT-based HTTP clients declared using the bill of materials (BOM) mechanism.

<project>
   <properties>
     <aws.sdk.version>2.27.21</aws.sdk.version>
  </properties>
  <dependencyManagement>
   <dependencies>
      <dependency>
        <groupId>software.amazon.awssdk</groupId>
        <artifactId>bom</artifactId>
        <version>${aws.sdk.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
   </dependencies>
  </dependencyManagement>
  <dependencies>
   <dependency>
      <groupId>software.amazon.awssdk</groupId>
      <artifactId>aws-crt-client</artifactId>
   </dependency>
  </dependencies>
</project>

Visit the Maven central repository for the latest version.

Use and configure an AWS CRT-based HTTP client

You can configure an AWS CRT-based HTTP client along with building a service client, or you can configure a single instance to share across multiple service clients.

With either approach, you use a builder to configure the properties for the AWS CRT-based HTTP client instance.

Best practice: dedicate an instance to a service client

If you need to configure an instance of an AWS CRT-based HTTP client, we recommend that you dedicate the instance by building it along with the service client . You can do so by using the httpClientBuilder method of the service client's builder. This way, the lifecycle of the HTTP client is managed by the SDK, which helps avoid potential memory leaks if the AWS CRT-based HTTP client instance is not closed down when it's no longer needed.

The following example creates an S3 service client and configures an AWS CRT-based HTTP client with connectionTimeout and maxConcurrency values.

Synchronous client

Imports

import software.amazon.awssdk.http.crt.AwsCrtHttpClient;
import software.amazon.awssdk.services.s3.S3Client;
import java.time.Duration;

Code

// Singleton: Use s3Client for all requests.
S3Client s3Client = S3Client.builder()
    .httpClientBuilder(AwsCrtHttpClient
        .builder()
        .connectionTimeout(Duration.ofSeconds(3))
        .maxConcurrency(100))
    .build();

// Perform work with the s3Client.

// Requests completed: Close the s3Client.
s3Client.close();
Asynchronous client

Imports

import software.amazon.awssdk.http.crt.AwsCrtAsyncHttpClient;
import software.amazon.awssdk.services.s3.S3AsyncClient;
import java.time.Duration;

Code

// Singleton: Use s3AsyncClient for all requests.
S3AsyncClient s3AsyncClient = S3AsyncClient.builder()
    .httpClientBuilder(AwsCrtAsyncHttpClient
        .builder()
        .connectionTimeout(Duration.ofSeconds(3))
        .maxConcurrency(100))
    .build();

// Perform work with the s3AsyncClient.

// Requests completed: Close the s3AsyncClient.
s3AsyncClient.close();

Alternative approach: share an instance

To help keep resource and memory usage lower for your application, you can configure an AWS CRT-based HTTP client and share it across multiple service clients. The HTTP connection pool will be shared, which lowers resource usage.

Note

When an AWS CRT-based HTTP client instance is shared, you must close it when it is ready to be disposed. The SDK will not close the instance when the service client is closed.

The following example configures an AWS CRT-based HTTP client instance with connectionTimeout and maxConcurrency values. The configured instance is passed to the httpClient method of each service client's builder. When the service clients and the HTTP client are no longer needed, they are explicitly closed. The HTTP client is closed last.

Synchronous client

Imports

import software.amazon.awssdk.auth.credentials.EnvironmentVariableCredentialsProvider;
import software.amazon.awssdk.awscore.defaultsmode.DefaultsMode;
import software.amazon.awssdk.http.SdkHttpClient;
import software.amazon.awssdk.http.crt.AwsCrtHttpClient;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.s3.S3Client;
import java.time.Duration;

Code

// Create an AwsCrtHttpClient shared instance.
SdkHttpClient crtHttpClient = AwsCrtHttpClient.builder()
    .connectionTimeout(Duration.ofSeconds(3))
    .maxConcurrency(100)
    .build();

// Singletons: Use the s3Client and dynamoDbClient for all requests.
S3Client s3Client = S3Client.builder()
    .httpClient(crtHttpClient)
    .credentialsProvider(EnvironmentVariableCredentialsProvider.crea
    .defaultsMode(DefaultsMode.IN_REGION)
    .region(Region.US_EAST_1)
    .build();

DynamoDbClient dynamoDbClient = DynamoDbClient.builder()
    .httpClient(crtHttpClient)
    .credentialsProvider(EnvironmentVariableCredentialsProvider.crea
    .defaultsMode(DefaultsMode.IN_REGION)
    .region(Region.US_EAST_1)
    .build();

// Requests completed: Close all service clients.
s3Client.close();
dynamoDbClient.close();
crtHttpClient.close();  // Explicitly close crtHttpClient.
Asynchronous client

Imports

import software.amazon.awssdk.auth.credentials.EnvironmentVariableCredentialsProvider;
import software.amazon.awssdk.awscore.defaultsmode.DefaultsMode;
import software.amazon.awssdk.http.async.SdkAsyncHttpClient;
import software.amazon.awssdk.http.crt.AwsCrtAsyncHttpClient;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbAsyncClient;
import software.amazon.awssdk.services.s3.S3AsyncClient;
import java.time.Duration;

Code

// Create an AwsCrtAsyncHttpClient shared instance.
SdkAsyncHttpClient crtAsyncHttpClient = AwsCrtAsyncHttpClient.builder()
    .connectionTimeout(Duration.ofSeconds(3))
    .maxConcurrency(100)
    .build();

// Singletons: Use the s3AsyncClient and dynamoDbAsyncClient for all requests.
S3AsyncClient s3AsyncClient = S3AsyncClient.builder()
    .httpClient(crtAsyncHttpClient)
    .credentialsProvider(EnvironmentVariableCredentialsProvider.create())
    .defaultsMode(DefaultsMode.IN_REGION)
    .region(Region.US_EAST_1)
    .build();

DynamoDbAsyncClient dynamoDbAsyncClient = DynamoDbAsyncClient.builder()
    .httpClient(crtAsyncHttpClient)
    .credentialsProvider(EnvironmentVariableCredentialsProvider.create())
    .defaultsMode(DefaultsMode.IN_REGION)
    .region(Region.US_EAST_1)
    .build();

// Requests completed: Close all service clients.
s3AsyncClient.close();
dynamoDbAsyncClient.close();
crtAsyncHttpClient.close();  // Explicitly close crtAsyncHttpClient.

Set an AWS CRT-based HTTP client as the default

You can setup your Maven build file to have the SDK use an AWS CRT-based HTTP client as the default HTTP client for service clients.

You do this by adding an exclusions element with the default HTTP client dependencies to each service client artifact.

In the following pom.xml example, the SDK uses an AWS CRT-based HTTP client for S3 services. If the service client in your code is an S3AsyncClient, the SDK uses AwsCrtAsyncHttpClient. If the service client is an S3Client, the SDK uses AwsCrtHttpClient. With this setup the default Netty-based asynchronous HTTP client and the default Apache-based synchronous HTTP are not available.

<project>
   <properties>
     <aws.sdk.version>VERSION</aws.sdk.version>
  </properties>
  <dependencies>
   <dependency>
      <groupId>software.amazon.awssdk</groupId>
      <artifactId>s3</artifactId>
      <version>${aws.sdk.version}</version>
      <exclusions>
         <exclusion>
            <groupId>software.amazon.awssdk</groupId>
            <artifactId>netty-nio-client</artifactId>
         </exclusion>
         <exclusion>
            <groupId>software.amazon.awssdk</groupId>
            <artifactId>apache-client</artifactId>
         </exclusion>
      </exclusions>
   </dependency>
   <dependency>
      <groupId>software.amazon.awssdk</groupId>
      <artifactId>aws-crt-client</artifactId>
   </dependency>
  </dependencies>
</project>

Visit the Maven central repository for the latest VERSION value.

Note

If multiple service clients are declared in a pom.xml file, all require the exclusions XML element.

Use a Java system property

To use the AWS CRT-based HTTP clients as the default HTTP for your application, you can set the Java system property software.amazon.awssdk.http.async.service.impl to a value of software.amazon.awssdk.http.crt.AwsCrtSdkHttpService.

To set during application startup, run a command similar to the following.

java app.jar -Dsoftware.amazon.awssdk.http.async.service.impl=\
software.amazon.awssdk.http.crt.AwsCrtSdkHttpService

Use the following code snippet to set the system property in your application code.

System.setProperty("software.amazon.awssdk.http.async.service.impl",
"software.amazon.awssdk.http.crt.AwsCrtSdkHttpService");
Note

You need to add a dependency on the aws-crt-client artifact in your poml.xml file when you use a system property to configure the use of the AWS CRT-based HTTP clients.

Advanced configuration of AWS CRT-based HTTP clients

You can use various configuration settings of the AWS CRT-based HTTP clients, including connection health configuration and maximum idle time. You can review the configuration options available for the AwsCrtAsyncHttpClient. You can configure the same options for the AwsCrtHttpClient.

Connection health configuration

You can configure connection health configuration for the AWS CRT-based HTTP clients by using the connectionHealthConfiguration method on the HTTP client builder.

The following example creates an S3 service client that uses a AWS CRT-based HTTP client instance configured with connection health configuration and a maximum idle time for connections.

Synchronous client

Imports

import software.amazon.awssdk.http.crt.AwsCrtHttpClient;
import software.amazon.awssdk.services.s3.S3Client;
import java.time.Duration;

Code

// Singleton: Use the s3Client for all requests.
S3Client s3Client = S3Client.builder()
    .httpClientBuilder(AwsCrtHttpClient
        .builder()
        .connectionHealthConfiguration(builder -> builder
            .minimumThroughputInBps(32000L)
            .minimumThroughputTimeout(Duration.ofSeconds(3)))
        .connectionMaxIdleTime(Duration.ofSeconds(5)))
    .build();

// Perform work with s3Client.

// Requests complete: Close the service client.
s3Client.close();
Asynchronous client

Imports

import software.amazon.awssdk.http.crt.AwsCrtAsyncHttpClient;
import software.amazon.awssdk.services.s3.S3AsyncClient;
import java.time.Duration;

Code

// Singleton: Use the s3AsyncClient for all requests.
S3AsyncClient s3AsyncClient = S3AsyncClient.builder()
    .httpClientBuilder(AwsCrtAsyncHttpClient
        .builder()
        .connectionHealthConfiguration(builder -> builder
            .minimumThroughputInBps(32000L)
            .minimumThroughputTimeout(Duration.ofSeconds(3)))
        .connectionMaxIdleTime(Duration.ofSeconds(5)))
    .build();

// Perform work with s3AsyncClient.

// Requests complete: Close the service client.
s3AsyncClient.close();

HTTP/2 support

The HTTP/2 protocol is not yet supported in the AWS CRT-based HTTP clients, but is planned for a future release.

In the meantime, if you are using service clients that require HTTP/2 support such as the KinesisAsyncClient or the TranscribeStreamingAsyncClient, consider using the NettyNioAsyncHttpClient instead.

Proxy configuration example

The following code snippet shows the use of the ProxyConfiguration.Builder that you use to configure proxy setting in code.

Synchronous client

Imports

import software.amazon.awssdk.http.SdkHttpClient;
import software.amazon.awssdk.http.crt.AwsCrtHttpClient;
import software.amazon.awssdk.http.crt.ProxyConfiguration;

Code

SdkHttpClient crtHttpClient = AwsCrtHttpClient.builder()
    .proxyConfiguration(ProxyConfiguration.builder()
        .scheme("https")
        .host("myproxy")
        .port(1234)
        .username("username")
        .password("password")
        .nonProxyHosts(Set.of("localhost", "host.example.com"))
        .build())
    .build();
Asynchronous client

Imports

import software.amazon.awssdk.http.async.SdkAsyncHttpClient;
import software.amazon.awssdk.http.crt.AwsCrtAsyncHttpClient;
import software.amazon.awssdk.http.crt.ProxyConfiguration;

Code

SdkAsyncHttpClient crtAsyncHttpClient = AwsCrtAsyncHttpClient.builder()
    .proxyConfiguration(ProxyConfiguration.builder()
        .scheme("https")
        .host("myproxy")
        .port(1234)
        .username("username")
        .password("password")
        .nonProxyHosts(Set.of("localhost", "host.example.com"))
        .build())
    .build();

The equivalent Java system properties for the proxy configuration are shown in the following command line snippet.

$ java -Dhttps.proxyHost=myproxy -Dhttps.proxyPort=1234 -Dhttps.proxyUser=username \
-Dhttps.proxyPassword=password -Dhttp.nonProxyHosts=localhost|host.example.com -cp ... App
Important

To use any of the HTTPS proxy system properties, the scheme property must be set in code to https. If the scheme property is not set in code, the scheme defaults to HTTP and the SDK looks only for http.* system properties.

The equivalent setup that uses environment variables is:

// Set the following environment variables.
// $ export HTTPS_PROXY="https://username:password@myproxy:1234"
// $ export NO_PROXY="localhost|host.example.com"

// Set the 'useSystemPropertyValues' to false on the proxy configuration.
SdkAsyncHttpClient crtAsyncHttpClient = AwsCrtAsyncHttpClient.builder()
    .proxyConfiguration(ProxyConfiguration.builder()
        .scheme("https")
        .useSystemPropertyValues(Boolean.FALSE)
        .build())
    .build();

// Run the application.
// $ java -cp ... App