Use PutRolePolicy with an AWS SDK or CLI

    /// <summary>
    /// Update the inline policy document embedded in a role.
    /// </summary>
    /// <param name="policyName">The name of the policy to embed.</param>
    /// <param name="roleName">The name of the role to update.</param>
    /// <param name="policyDocument">The policy document that defines the role.</param>
    /// <returns>A Boolean value indicating the success of the action.</returns>
    public async Task<bool> PutRolePolicyAsync(string policyName, string roleName, string policyDocument)
    {
        var request = new PutRolePolicyRequest
        {
            PolicyName = policyName,
            RoleName = roleName,
            PolicyDocument = policyDocument
        };

        var response = await _IAMService.PutRolePolicyAsync(request);
        return response.HttpStatusCode == HttpStatusCode.OK;
    }

bool AwsDoc::IAM::putRolePolicy(
        const Aws::String &roleName,
        const Aws::String &policyName,
        const Aws::String &policyDocument,
        const Aws::Client::ClientConfiguration &clientConfig) {
    Aws::IAM::IAMClient iamClient(clientConfig);
    Aws::IAM::Model::PutRolePolicyRequest request;

    request.SetRoleName(roleName);
    request.SetPolicyName(policyName);
    request.SetPolicyDocument(policyDocument);

    Aws::IAM::Model::PutRolePolicyOutcome outcome = iamClient.PutRolePolicy(request);
    if (!outcome.IsSuccess()) {
        std::cerr << "Error putting policy on role. " <<
                  outcome.GetError().GetMessage() << std::endl;
    }
    else {
        std::cout << "Successfully put the role policy." << std::endl;
    }

    return outcome.IsSuccess();
}

To attach a permissions policy to an IAM role

The following put-role-policy command adds a permissions policy to the role named Test-Role.

aws iam put-role-policy \
    --role-name Test-Role \
    --policy-name ExamplePolicy \
    --policy-document file://AdminPolicy.json

This command produces no output.

The policy is defined as a JSON document in the AdminPolicy.json file. (The file name and extension do not have significance.)

To attach a trust policy to a role, use the update-assume-role-policy command.

For more information, see Modifying a role in the AWS IAM User Guide.

import { PutRolePolicyCommand, IAMClient } from "@aws-sdk/client-iam";

const examplePolicyDocument = JSON.stringify({
  Version: "2012-10-17",
  Statement: [
    {
      Sid: "VisualEditor0",
      Effect: "Allow",
      Action: [
        "s3:ListBucketMultipartUploads",
        "s3:ListBucketVersions",
        "s3:ListBucket",
        "s3:ListMultipartUploadParts",
      ],
      Resource: "arn:aws:s3:::some-test-bucket",
    },
    {
      Sid: "VisualEditor1",
      Effect: "Allow",
      Action: [
        "s3:ListStorageLensConfigurations",
        "s3:ListAccessPointsForObjectLambda",
        "s3:ListAllMyBuckets",
        "s3:ListAccessPoints",
        "s3:ListJobs",
        "s3:ListMultiRegionAccessPoints",
      ],
      Resource: "*",
    },
  ],
});

const client = new IAMClient({});

/**
 *
 * @param {string} roleName
 * @param {string} policyName
 * @param {string} policyDocument
 */
export const putRolePolicy = async (roleName, policyName, policyDocument) => {
  const command = new PutRolePolicyCommand({
    RoleName: roleName,
    PolicyName: policyName,
    PolicyDocument: policyDocument,
  });

  const response = await client.send(command);
  console.log(response);
  return response;
};

Example 1: This example creates an inline policy named FedTesterRolePolicy and embeds it in the IAM role FedTesterRole. If an inline policy with the same name already exists, then it is overwritten. The JSON policy content comes from the file FedTesterPolicy.json. Note that you must use the -Raw parameter to successfully process the content of the JSON file.

Write-IAMRolePolicy -RoleName FedTesterRole -PolicyName FedTesterRolePolicy -PolicyDocument (Get-Content -Raw FedTesterPolicy.json)