Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Use profiles

Using the shared config and credentials file, you can set up several profiles. This enables your application to use multiple sets of credentials configuration. The [default] profile was mentioned previously. The SDK uses the ProfileCredentialsProvider class to load settings from profiles defined in the shared credentials file.

The following code snippet demonstrates how to build a service client that uses the settings defined as part of the profile named my_profile.

Region region = Region.US_WEST_2;
DynamoDbClient ddb = DynamoDbClient.builder()
      .region(region)
      .credentialsProvider(ProfileCredentialsProvider.create("my_profile"))
      .build();

Set a different profile as the default

To set a profile other than the [default] profile as the default for your application, set the AWS_PROFILE environment variable to the name of your custom profile.

To set this variable on Linux, macOS, or Unix, use export:

export AWS_PROFILE="other_profile"

To set these variables on Windows, use set:

set AWS_PROFILE="other_profile"

Alternatively, set the aws.profile Java system property to the name of the profile.

Reload profile credentials

You can configure any credentials provider that has a profileFile() method on its builder to reload profile credentials. These credentials profile classes are: ProfileCredentialsProvider, DefaultCredentialsProvider, InstanceProfileCredentialsProvider, and ProfileTokenProvider.

To configure a supported credentials provider to reload profile settings, provide an instance of ProfileFileSupplier to the profileFile() builder method. The following code example demonstrates a ProfileCredentialsProvider that reloads credential settings from the [default] profile.

ProfileCredentialsProvider provider = ProfileCredentialsProvider
    .builder()
    .profileFile(ProfileFileSupplier.defaultSupplier())
    .build();

// Set up a service client with the provider instance.
DynamoDbClient dynamoDbClient = DynamoDbClient.builder()
                    .region(Region.US_EAST_1)
                    .credentialsProvider(provider)
                    .build();

/*
    Before dynamoDbClient makes a request, it reloads the credentials settings 
    by calling provider.resolveCredentials().
*/

When ProfileCredentialsProvider.resolveCredentials() is called, the SDK for Java reloads the settings. ProfileFileSupplier.defaultSupplier() is one of several convenience implementations of ProfileFileSupplier provided by the SDK. If your use case requires, you can provide your own implementation.

The following example shows the use of the ProfileFileSupplier.reloadWhenModified() convenience method. reloadWhenModified() takes a Path parameter, which gives you flexibility in designating the source file for the configuration rather than the standard ~/.aws/credentials (or config) location.

The settings will be reloaded when resolveCredentials() is called only if SDK determines the file's content has been modified.

Path credentialsFilePath = ...

ProfileCredentialsProvider provider = ProfileCredentialsProvider
    .builder()
    .profileFile(ProfileFileSupplier.reloadWhenModified(credentialsFilePath, ProfileFile.Type.CREDENTIALS))
    .profileName("my-profile")
    .build();
/*
    A service client configured with the provider instance calls provider.resolveCredential()
    before each request.
*/

The ProfileFileSupplier.aggregate() method merges the contents of multiple configuration files. You decide whether a file is reloaded per call to resolveCredentials() or a file's settings are fixed at the time it was first read.

The following example shows a DefaultCredentialsProvider that merges the settings of two files that contain profile settings. The SDK reloads the settings in the file pointed to by the credentialsFilePath variable each time resolveCredentials() is called and the settings have changed. The settings from the profileFile object remain the same.

Path credentialsFilePath = ...;
ProfileFile profileFile = ...;

DefaultCredentialsProvider provider = DefaultCredentialsProvider
        .builder()
        .profileFile(ProfileFileSupplier.aggregate(
                ProfileFileSupplier.reloadWhenModified(credentialsFilePath, ProfileFile.Type.CREDENTIALS),
                ProfileFileSupplier.fixedProfileFile(profileFile)))
        .profileName("my-profile")
        .build();
/*
    A service client configured with the provider instance calls provider.resolveCredential()
    before each request.
*/