Amazon Bedrock Integration

Relevant source files

The following files were used as context for generating this wiki page:

• bedrock/bedrock.go
• examples/bedrock/main.go
• examples/bedrock-streaming/main.go
• examples/bedrock-bearer-token/main.go
• bedrock/bedrock_test.go
• internal/awsauth/awsauth.go

The Amazon Bedrock Integration module enables the Anthropic Go SDK to communicate directly with Claude models hosted on Amazon Bedrock. It provides a seamless transition from the standard Anthropic API to the Bedrock Runtime by intercepting requests via middleware, handling AWS-specific authentication (SigV4 or Bearer Token), and remapping request/response formats to match Bedrock's requirements.

This integration is primarily contained within the bedrock package and leverages internal AWS authentication utilities. It supports both standard synchronous message creation and streaming responses using the Amazon EventStream protocol.

Sources: bedrock/bedrock.go:1-25, internal/awsauth/awsauth.go:1-20

Architecture and Middleware

The core of the integration is a custom HTTP middleware that transforms standard Anthropic API requests into a format compatible with the Amazon Bedrock Runtime API. This middleware handles URL path remapping, body modification, and authentication header injection.

Request Transformation Flow

When a request is initiated through a client configured with Bedrock options, the following transformations occur:

1. Version Injection: If anthropic_version is missing from the body, it defaults to bedrock-2023-05-31.
2. Beta Header Routing: Headers like anthropic-beta are removed from the HTTP headers and moved into the JSON request body under the anthropic_beta field.
3. Endpoint Remapping: Standard paths like /v1/messages are rewritten to Bedrock's structure: /model/{model_id}/invoke or /model/{model_id}/invoke-with-response-stream.

The diagram above shows the sequential transformation steps performed by the middleware to make a standard request compatible with AWS Bedrock.
Sources: bedrock/bedrock.go:189-235, bedrock/bedrock_test.go:133-150

Configuration and Authentication

The SDK provides multiple ways to configure the Bedrock client, supporting standard AWS credential chains, environment variables, and programmatic token providers.

Authentication Methods

Method	Description	Configuration Source
AWS SigV4	Standard AWS signing using Access Key, Secret Key, and optionally Session Token.	aws.Config.Credentials or AWS_REGION
Bearer Token	Uses a static token for authentication, specific to certain Bedrock configurations.	AWS_BEARER_TOKEN_BEDROCK or BearerAuthTokenProvider
Default Config	Automatically loads AWS configuration from the environment/shared files.	bedrock.WithLoadDefaultConfig()

Sources: bedrock/bedrock.go:167-187, internal/awsauth/awsauth.go:121-145

Key Functions

• WithConfig(cfg aws.Config): Returns a RequestOption that registers the Bedrock middleware using a pre-configured AWS config.
• WithLoadDefaultConfig(ctx context.Context, ...): Helper to load the default AWS SDK configuration and apply Bedrock settings.
• NewStaticBearerTokenProvider(token string): Creates a provider for static token-based authentication.

Sources: bedrock/bedrock.go:151-175, examples/bedrock-bearer-token/main.go:16-25

Streaming and EventStream Decoding

Bedrock uses the application/vnd.amazon.eventstream content type for streaming responses, which differs from the standard Server-Sent Events (SSE) used by the Anthropic API. The SDK includes a specialized eventstreamDecoder to bridge this gap.

EventStream Processing logic

The decoder listens for AWS EventStream chunks, extracts the base64-encoded payload, and converts it back into standard Anthropic stream events.

The sequence diagram illustrates how the binary protocol from AWS is translated into the iterative stream used by the Go SDK.
Sources: bedrock/bedrock.go:50-130

Implementation Example

Integrating Bedrock involves passing the bedrock-specific request options during client initialization.

// Initializing with default AWS environment variables
client := anthropic.NewClient(
    bedrock.WithLoadDefaultConfig(context.Background()),
)

// The client now uses Bedrock-specific model IDs
message, err := client.Messages.New(ctx, anthropic.MessageNewParams{
    Model:     "us.anthropic.claude-sonnet-4-5-20250929-v1:0",
    MaxTokens: 1024,
    Messages:  []anthropic.MessageParam{...},
})

Sources: examples/bedrock/main.go:11-30, examples/bedrock-bearer-token/main.go:30-40

URL Encoding and ARNs

The integration handles complex model identifiers, including Amazon Resource Names (ARNs) for foundation models and inference profiles. Colons and slashes in ARNs are automatically escaped for the RawPath while remaining readable in the standard Path.

Model Identifier Type	Example Value	Remapped Path Segment
Model Name	claude-3-sonnet	/model/claude-3-sonnet/...
Foundation ARN	arn:aws:bedrock:us-east-1:123:foundation-model/anthropic.claude-3-v1:0	/model/arn%3Aaws%3Abedrock.../invoke
Inference Profile	arn:aws:bedrock:us-east-1:123:application-inference-profile/profile-id	/model/arn%3Aaws%3Abedrock.../invoke

Sources: bedrock/bedrock_test.go:20-55

The Amazon Bedrock Integration module successfully abstracts the complexities of AWS-specific protocols and authentication, allowing Go developers to use the familiar Anthropic SDK interface while targeting infrastructure hosted on AWS.