Configure the Apache-based HTTP client

Synchronous service clients in the AWS SDK for Java 2.x use an Apache-based HTTP client, ApacheHttpClient by default. The SDK's ApacheHttpClient is based on the Apache HttpClient.

The SDK also offers the UrlConnectionHttpClient, which loads more quickly, but has fewer features. For information about configuring the UrlConnectionHttpClient, see Configure the URLConnection-based HTTP client.

To see the full set of configuration options available to you for the ApacheHttpClient, see ApacheHttpClient.Builder and ProxyConfiguration.Builder.

Access the ApacheHttpClient

In most situations, you use the ApacheHttpClient without any explicit configuration. You declare your service clients and the SDK will configure the ApacheHttpClient with standard values for you.

If you want to explicitly configure the ApacheHttpClient or use it with multiple service clients, you need to make it available for configuration.

No configuration needed

When you declare a dependency on a service client in Maven, the SDK adds a runtime dependency on the apache-client artifact. This makes the ApacheHttpClient class available to your code at runtime, but not at compile time. If you are not configuring the Apache-based HTTP client, you do not need to specify a dependency for it.

In the following XML snippet of a Maven pom.xml file, the dependency declared with <artifactId>s3</artifactId> automatically brings in the Apache-based HTTP client. You don't need to declare a dependency specifically for it.

<dependencyManagement>
   <dependencies>
        <dependency>
            <groupId>software.amazon.awssdk</groupId>
            <artifactId>bom</artifactId>
            <version>2.27.21</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>
<dependencies>
    <!-- The s3 dependency automatically adds a runtime dependency on the ApacheHttpClient-->
    <dependency>
        <groupId>software.amazon.awssdk</groupId>
        <artifactId>s3</artifactId>
    </dependency>
</dependencies>

With these dependencies, you cannot make any explicit HTTP configuration changes, because the ApacheHttpClient library is only on the runtime classpath.

Configuration needed

To configure the ApacheHttpClient, you need to add a dependency on the apache-client library at compile time.

Refer to the following example of a Maven pom.xml file to configure the ApacheHttpClient.

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>software.amazon.awssdk</groupId>
                <artifactId>bom</artifactId>
                <version>2.27.21</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>software.amazon.awssdk</groupId>
            <artifactId>s3</artifactId>
        </dependency>
        <!-- By adding the apache-client dependency, ApacheHttpClient will be added to 
             the compile classpath so you can configure it. -->
        <dependency>
            <groupId>software.amazon.awssdk</groupId>
            <artifactId>apache-client</artifactId>
        </dependency>
    </dependencies>

Use and configure the ApacheHttpClient

You can configure an instance of ApacheHttpClient along with building a service client, or you can configure a single instance to share across multiple service clients.

With either approach, you use the ApacheHttpClient.Builder to configure the properties for the Apache-based HTTP client.

Best practice: dedicate an ApacheHttpClient instance to a service client

If you need to configure an instance of the ApacheHttpClient, we recommend that you build the dedicated ApacheHttpClient instance. 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 ApacheHttpClient instance is not closed down when it's no longer needed.

The following example creates an S3Client and configures the embedded instance of ApacheHttpClient with maxConnections and connectionTimeout values. The HTTP instance is created using the httpClientBuilder method of S3Client.Builder.

Imports

import software.amazon.awssdk.http.apache.ApacheHttpClient;
import software.amazon.awssdk.services.s3.S3Client;
import java.time.Duration;

Code

S3Client s3Client = S3Client   // Singleton: Use the s3Client for all requests.
    .builder()
    .httpClientBuilder(ApacheHttpClient.builder()
        .maxConnections(100)
        .connectionTimeout(Duration.ofSeconds(5))
    ).build();

// Perform work with the s3Client.

s3Client.close();   // Requests completed: Close all service clients.

Alternative approach: share an ApacheHttpClient instance

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

Note

When an ApacheHttpClient 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 Apache-based HTTP client that is used by two service clients. The configured ApacheHttpClient instance is passed to the httpClient method of each builder. When the service clients and the HTTP client are no longer needed, the code explicitly closes them. The code closes the HTTP client last.

Imports

import software.amazon.awssdk.http.SdkHttpClient;
import software.amazon.awssdk.http.apache.ApacheHttpClient;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.s3.S3Client;

Code

SdkHttpClient apacheHttpClient = ApacheHttpClient.builder()
        .maxConnections(100).build();

// Singletons: Use the s3Client and dynamoDbClient for all requests.
S3Client s3Client = 
    S3Client.builder()
            .httpClient(apacheHttpClient).build();

DynamoDbClient dynamoDbClient = 
    DynamoDbClient.builder()
                  .httpClient(apacheHttpClient).build();

// Perform work with the s3Client and dynamoDbClient.

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

Proxy configuration example

The following code snippet uses the proxy configuration builder for the Apache HTTP client.

SdkHttpClient apacheHttpClient = ApacheHttpClient.builder()
                .proxyConfiguration(ProxyConfiguration.builder()
                        .endpoint(URI.create("http://example.com:1234"))
                        .username("username")
                        .password("password")
                        .addNonProxyHost("localhost")
                        .addNonProxyHost("host.example.com")
                        .build())
                .build();

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

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

The equivalent setup that uses environment variables is:

// Set the following environment variables.
// $ export HTTP_PROXY="http://username:[e-mail]:1234"
// $ export NO_PROXY="localhost|host.example.com"

// Set the 'useSystemPropertyValues' to false on the proxy configuration.
SdkHttpClient apacheHttpClient = ApacheHttpClient.builder()
                .proxyConfiguration(ProxyConfiguration.builder()
                        .useSystemPropertyValues(Boolean.FALSE)
                        .build())
                .build();

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

Note

The Apache HTTP client does not currently support HTTPS proxy system properties or the HTTPS_PROXY environment variable.