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Sign requests to an AWS service with AWS Signature Version 4, optionally through an assumed IAM role.

Attaches to:

Configuration examples

To sign requests to an AWS service, use aws. Unlike the other methods, aws does not attach a token. It computes an AWS Signature Version 4 signature over the request, so it runs last, after every other policy that changes the request.

Name an access key explicitly, or omit the credential fields to use the standard AWS credential chain.

backendAuth:
  aws:
    accessKeyId: "$AWS_ACCESS_KEY_ID"
    secretAccessKey: "$AWS_SECRET_ACCESS_KEY"
    sessionToken: "$AWS_SESSION_TOKEN"
    region: us-west-2
    serviceName: execute-api

backendAuth:
  aws:
    region: us-east-1
    serviceName: bedrock

AWS credential resolution order

When you omit accessKeyId and secretAccessKey, agentgateway uses the default credential chain of the AWS SDK. The chain tries the following sources in order and stops at the first one that returns credentials.

1. Environment variables: AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, and AWS_SESSION_TOKEN.
2. Shared configuration files: ~/.aws/config and ~/.aws/credentials.
3. Web identity token: AWS_WEB_IDENTITY_TOKEN_FILE and AWS_ROLE_ARN. This is the source that IAM roles for service accounts and EKS Pod Identity use.
4. Container credentials: the credential endpoint that Amazon ECS and other container hosts provide.
5. Instance metadata: IMDSv2 on an EC2 instance.

Assume a role

To sign with a role rather than with the identity of agentgateway, set assumeRole. Agentgateway calls the AWS Security Token Service (STS) with the credentials from the chain, and signs with the credentials that STS returns. It caches the assumed credentials and refreshes them before they expire.

Create the IAM role in AWS before you set the field. The role needs a permissions policy that allows the actions of the service that you call, such as bedrock:InvokeModel for Amazon Bedrock. It also needs a trust policy that allows the identity of agentgateway to assume it. Which permissions you attach therefore depends on the service that the backend fronts. For the steps, see Create a role to delegate permissions to an AWS service in the AWS documentation.

The session name and the session tags exist for cost attribution. Each accepts a static value, or a CEL expression that agentgateway evaluates against every request, which lets one gateway attribute cost per user or per team.

backendAuth:
  aws:
    region: us-east-1
    serviceName: bedrock
    assumeRole:
      roleArn: arn:aws:iam::123456789012:role/agentgateway-bedrock
      sessionName:
        expression: jwt.sub
      tags:
      - key: team
        value: platform
      - key: user
        expression: jwt.sub