An error occurred (SignatureDoesNotMatch) when calling the ListBuckets operation

The error message “An error occurred (SignatureDoesNotMatch) when calling the ListBuckets operation” in AWS (Amazon Web Services) indicates that there’s a mismatch between the request signature calculated by AWS and the signature you provided. AWS relies on two key components for authentication: the AWS Access Key ID and the AWS Secret Access Key. The Secret Access Key is used for securely signing requests to AWS services. When you encounter this error, it typically signifies that the provided AWS Secret Access Key is incorrect or has been used with an inappropriate signing method.

Pulumi ESC (Environments, Secrets, and Configurations) offers a solution to the challenges of managing credentials and can make errors like this a thing of the past. By enabling the management of dynamic credentials from AWS using OIDC, Pulumi ESC simplifies and secures your AWS CLI operations. This approach eliminates the need for manually providing credentials and is a more secure solution than the use of long-term credentials, which can often present a security risk. Pulumi ESC also enables you to focus on your tasks without the interruption of credential-related errors, providing a more efficient flow for your AWS operations and tasks.

Using Pulumi ESC for dynamic credentials with AWS

Pulumi ESC is a service that helps to alleviate the burden of managing cloud configuration and secrets by providing a centralized way to handle these critical aspects of cloud development. The esc run command of this service in particular helps to resolve concerns around how to:

  • Securely share credentials with teammates in a consistent way.
  • Minimize the risks associated with locally configured, long-lived and highly privileged credentials.
  • Ensure teams can easily and safely run commands like without requiring deep security expertise.

What is the esc run command?

The Pulumi documentation for the esc run command states the following:

This command opens the environment with the given name and runs the given command. If the opened environment contains a top-level ’environmentVariables’ object, each key-value pair in the object is made available to the command as an environment variable.

But what does this actually mean? If we use AWS as an example, it means that we can run commands like aws s3 ls without the need to configure AWS credentials locally each time. It’s a significant stride towards making your cloud interactions more efficient and less error-prone, and here’s a deeper dive into why:

  • Seamless Command Execution - The esc run command lets you execute AWS commands effortlessly, freeing you from the intricacies of managing AWS credentials on your local machine. Simply put, it significantly reduces the overhead of credential setup and maintenance.

  • Enhanced Security - One of the standout features of esc run is its commitment to security. By removing the local storage of credentials, it drastically reduces the risk of accidental exposure. Your credentials and secrets are securely managed within the Pulumi environment.

  • Streamlined Collaboration - Because credentials will be centralized, esc run facilitates smoother team collaboration by providing a consistent environment for all team members to run commands with. Everyone can access the same secure environment which reduces the complexities of coordinating credentials and configurations across teams.

Getting started with esc run

Step 1: Install and login to Pulumi ESC

To begin, you’ll need to install Pulumi ESC. Once the installation is complete, run the esc login command and follow the steps to login to the CLI.

$ esc login
Manage your Pulumi ESC environments by logging in.
Run `esc --help` for alternative login options.
Enter your access token from
    or hit <ENTER> to log in using your browser                   :
Logged in to as …

Step 2: Create the OIDC configuration

Pulumi ESC offers you the ability to manually set your credentials as secrets in your Pulumi ESC environment files. When it comes to something like OIDC configuration, a more secure and efficient alternative is to leverage yet another great feature of Pulumi ESC: dynamic credentials.

This service can dynamically generate credentials on your behalf each time you need to interact with your AWS environments. To do so, follow the steps in the guide for configuring OIDC between Pulumi and AWS. Make sure that the IAM role you create has sufficient permissions to perform S3 actions.

Step 3: Create a new Pulumi ESC environment

Once OIDC has been configured between Pulumi and AWS, the next steps is to create a new environment in the Pulumi Cloud. Make sure that you have the correct organization selected in the left-hand navigation menu. From there, click the Environments link, then click the Create environment button. In the following pop-up, provide a name for your environment before clicking the Create environment button.

Step 4: Add the AWS provider integration

Once you’ve created your new environment, you will be presented with a split-pane editor view. You’ll want to clear out the default placeholder content in the editor on the left-hand side and replace it with the following code, making sure to replace with the value of your IAM role ARN from the configure OIDC step:

          duration: 1h
          roleArn: <your-oidc-iam-role-arn>
          sessionName: pulumi-environments-session
    AWS_ACCESS_KEY_ID: ${aws.login.accessKeyId}
    AWS_SECRET_ACCESS_KEY: ${aws.login.secretAccessKey}
    AWS_SESSION_TOKEN: ${aws.login.sessionToken}

Step 5: Run the aws CLI command

With your environment set up, you can validate your configuration and verify that the error has been resolved by running the aws s3 ls command using esc run as shown below, making sure to replace <your-pulumi-org-name> and <your-environment-name> with the names of your own Pulumi organization and environment respectively:

esc run <your-pulumi-org-name>/<your-environment-name> -i aws s3 ls --query "Buckets[].Name"


Pulumi ESC makes it easier than ever to tame infrastructure complexity, especially when running commands like aws s3 ls. Because Pulumi ESC supports dynamic credentials using OIDC across AWS, Azure, and Google Cloud, you no longer have to worry about credential errors like “SignatureDoesNotMatch” as the service will dynamically generate and refresh them for you. Check out the following links to learn more about Pulumi ESC today.

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