AssumeRole API - Authorization

You need to ensure you fill out the AWS required Parameters in the Authorization Tab which includes the IAM Access Key, Secret and Session Token

Hi,

All requests that you make to AWS service API need to be signed with the SigV4 protocol: https://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-authenticating-requests.html

You follow the above to code your signature algorithm but it's quite some work.

My recommendation is to call AWS APIs using the SDK of your preferred language. AWS supports multiple languages: https://aws.amazon.com/developer/tools/

And if you don't want to use any AWS SDK, you can at least download its source code for your preferred language to see (and use... : it's OSS) its code to create your own signing code.

Best,

Didier

Does this work for you??

const AWS = require('aws-sdk');

// Your IAM access key and secret
const ACCESS_KEY = 'YOUR_ACCESS_KEY';
const SECRET_KEY = 'YOUR_SECRET_KEY';

// Configure AWS SDK
AWS.config.update({
  accessKeyId: ACCESS_KEY,
  secretAccessKey: SECRET_KEY,
  region: 'us-east-1', // Adjust to your desired region
});

const sts = new AWS.STS();

async function assumeRole() {
  const params = {
    RoleArn: 'arn:aws:iam::123456789012:role/YourRoleName', // Replace with the ARN of the role to assume
    RoleSessionName: 'YourSessionName', // A unique session name
  };

  try {
    const data = await sts.assumeRole(params).promise();
    console.log('Assumed Role Credentials:', data.Credentials);

    // Use the temporary credentials to make further AWS SDK calls
    const tempCredentials = {
      accessKeyId: data.Credentials.AccessKeyId,
      secretAccessKey: data.Credentials.SecretAccessKey,
      sessionToken: data.Credentials.SessionToken,
    };

    // Example: Use the assumed role credentials to list S3 buckets
    const s3 = new AWS.S3(tempCredentials);

    const s3Buckets = await s3.listBuckets().promise();
    console.log('S3 Buckets:', s3Buckets);
  } catch (error) {
    console.error('Error assuming role:', error);
  }
}

assumeRole();

Appoligies as you had IAM Keys in the original question i thought it was running as a user than a Role.. You need to extract the IAM keys and tokens when trying to assume the new role

How about

const AWS = require('aws-sdk');

exports.handler = async (event) => {
    // Configure STS
    const sts = new AWS.STS();

    try {
        // Assume the target role
        const assumeRoleResponse = await sts.assumeRole({
            RoleArn: 'arn:aws:iam::123456789012:role/TargetRoleName', // Replace with your target role ARN
            RoleSessionName: 'SessionName' // Unique identifier for the session
        }).promise();

        // Extract temporary credentials
        const { AccessKeyId, SecretAccessKey, SessionToken } = assumeRoleResponse.Credentials;

        // Use temporary credentials to configure a new AWS service client
        const s3 = new AWS.S3({
            accessKeyId: AccessKeyId,
            secretAccessKey: SecretAccessKey,
            sessionToken: SessionToken
        });

        // Example S3 call using temporary credentials
        const s3Response = await s3.listBuckets().promise();

        console.log('S3 Buckets:', s3Response.Buckets);

        return {
            statusCode: 200,
            body: JSON.stringify({ message: 'AssumeRole success', buckets: s3Response.Buckets })
        };
    } catch (error) {
        console.error('Error assuming role:', error);
        return {
            statusCode: 500,
            body: JSON.stringify({ message: 'Error assuming role', error: error.message })
        };
    }
};