Pulumi CrossGuard policies for AWS (AWSGuard)

CrossGuard is a beta feature and is subject to breaking changes. The open source --policy-pack flag is free and available for all to use. A preview of CrossGuard is also available in the Pulumi Console, which enables you to enforce policies across an organization. To get access, submit a request here.

Overview

AWSGuard codifies best practices for AWS. It is an open source library that you can configure and use to enforce these best practices for your own Pulumi stacks or organization.

For more information on Pulumi’s Policy as Code solution, visit our docs.

Trying AWSGuard

In this guide, we’ll show you how to create a Policy Pack that configures and uses the policies available in AWSGuard.

Prerequisites

Verify your version of the Pulumi CLI

pulumi version # should be v1.6.1 or later

Authoring a Policy Pack that uses AWSGuard policies

To use AWSGuard policies, you must create a Policy Pack that references the @pulumi/awsguard npm package and creates a new instance of the AwsGuard class.

  1. Create a directory for your new Policy Pack, and change into it.

    mkdir awsguard && cd awsguard
  2. Run the pulumi policy new command. Since Policy as Code is in preview, you will need to set PULUMI_EXPERIMENTAL=true as an environment variable.

    On macOS, you can run export PULUMI_EXPERIMENTAL=true or simply prepend it to your commands as shown.

    $ PULUMI_EXPERIMENTAL=true pulumi policy new awsguard-typescript

    On Linux, you can run export PULUMI_EXPERIMENTAL=true or simply prepend it to your commands as shown.

    $ PULUMI_EXPERIMENTAL=true pulumi policy new awsguard-typescript

    On Windows, you must first set the environment variable before running the command.

    Windows cmd.exe

    set PULUMI_EXPERIMENTAL=true
    pulumi policy new awsguard-typescript

    Windows PowerShell

    $env:PULUMI_EXPERIMENTAL = 'true'
    pulumi policy new awsguard-typescript
  3. Tweak the code in the index.ts file as desired. The default implementation provided by the awsguard-typescript template simply creates a new instance of AwsGuard with all policies set to have an enforcement level of advisory.

    new AwsGuard({ all: "advisory" });

    From here, you can change the enforcement level for all policies or configure individual policies.

    For example:

    To make all policies mandatory rather than advisory:

    new AwsGuard({ all: "mandatory" });

    To make all policies mandatory, but change certain policies to be advisory:

    new AwsGuard({
        all: "mandatory",
        ec2InstanceNoPublicIP: "advisory",
        elbAccessLoggingEnabled: "advisory",
    });

    To disable a particular policy:

    new AwsGuard({
        ec2InstanceNoPublicIP: "disabled",
    });

    To disable all policies except ones explicitly enabled:

    new AwsGuard({
        all: "disabled",
        ec2InstanceNoPublicIP: "mandatory",
        elbAccessLoggingEnabled: "mandatory",
    });

    To specify additional configuration for policies that support it:

    new AwsGuard({
        ec2VolumeInUseCheck: { checkDeletion: false },
        encryptedVolumes: { enforcementLevel: "mandatory", kmsId: "id" },
        redshiftClusterMaintenanceSettingsCheck: { preferredMaintenanceWindow: "Mon:09:30-Mon:10:00" },
        acmCheckCertificateExpiration: { maxDaysUntilExpiration: 10 },
    });

Test the new Policy Pack

Policy Packs can be tested on a user’s local workstation to facilitate rapid development and testing of policies.

  1. Run npm install in the Policy Pack directory.

  2. Use the --policy-pack flag with pulumi preview or pulumi up to specify the path to the directory containing your Policy Pack when previewing/updating a Pulumi program.

    If you don’t have a Pulumi program readily available, you can create a new project for testing by running pulumi new aws-typescript in an empty directory. This AWS example will create an S3 bucket, which is perfect for testing our Policy.

    In the Pulumi project’s directory run:

    $ PULUMI_EXPERIMENTAL=true pulumi preview --policy-pack <path-to-policy-pack-directory>
    $ PULUMI_EXPERIMENTAL=true pulumi preview --policy-pack <path-to-policy-pack-directory>

    Windows cmd.exe

    set PULUMI_EXPERIMENTAL=true
    pulumi preview --policy-pack <path-to-policy-pack-directory>

    Windows PowerShell

    $env:PULUMI_EXPERIMENTAL = 'true'
    pulumi preview --policy-pack <path-to-policy-pack-directory>

    If the stack is not in compliance, the policy violation will be displayed. Since the enforcement level for all policies are set to advisory, a warning is shown for any resources that are not in compliance with the AWSGuard policies. In this case, logging must be defined for S3 buckets.

    Previewing update (dev):
    
        Type                 Name           Plan       Info
    +   pulumi:pulumi:Stack  test-dev       create
    +   └─ aws:s3:Bucket     my-bucket      create     1 warning
    
    Diagnostics:
    aws:s3:Bucket (my-bucket):
        advisory: [s3-bucket-logging-enabled] Checks whether logging is enabled for your S3 buckets.
        Bucket logging must be defined.
    
    Resources:
        + 2 to create
  3. If you had wanted the preview to fail for any policy violations, the Policy Pack can be modified to configure all policies to be mandatory.

    new AwsGuard({ all: "mandatory" });
  4. Running the pulumi preview command again will now fail the preview operation.

    Previewing update (dev):
    
        Type                 Name           Plan       Info
    +   pulumi:pulumi:Stack  test-dev       create     1 error
    +   └─ aws:s3:Bucket     my-bucket      create     1 error
    
    Diagnostics:
    pulumi:pulumi:Stack (test-dev):
        error: preview failed
    
    aws:s3:Bucket (my-bucket):
        mandatory: [s3-bucket-logging-enabled] Checks whether logging is enabled for your S3 buckets.
        Bucket logging must be defined.
  5. If you do not want to enforce this particular policy, you can modify the Policy Pack to disable it.

    new AwsGuard({
        all: "mandatory",
        s3BucketLoggingEnabled: "disabled",
    });

Next Steps

Once you’ve validated the behavior of the AWSGuard policies you’ve configured in your Policy Pack, an organization administrator can publish the Policy Pack to the Pulumi Console to be enforced across your organization. To learn more see Enforcing a Policy Pack Across an Organization.

Now that you’ve seen how to configure and use AWSGuard policies, you may want to write your own policies. See the Getting Started tutorial to get started.