pulumi-policy 0.4.1.dev1585605506

Pulumi's Policy Python SDK

Pulumi Policy Framework

Status: preview release

Overview

Define and manage policy for cloud resources deployed through for Pulumi.

Policy rules run during pulumi preview and pulumi up, asserting that cloud resource definitions comply with the policy immediately before they are created or updated.

During preview, every every rule is run on every resource, and policy violations are batched up into a final report. During the update, the first policy violation will halt the deployment.

Policy violations can have enforcement levels that are advisory, which results in a printed warning, or mandatory, which results in an error after pulumi preview or pulumi up complete.

Examples

Looking for examples? The @pulumi/policy module is the core SDK for authoring new Pulumi policies using code. To find examples of existing policy packs, please refer to the examples repo.

Trying the Policy Framework

In this guide, we'll show you how to install the required packages, and take a brief tour of the Policy SDK.

This beta feature is also available via the Pulumi Console. To get this feature enabled for your Pulumi organization, you can reach out to us via email or this Contact Us form.

Prerequisites

• Install Pulumi
• Install Node.js version 8 or later

Verify your version of the Pulumi CLI

pulumi version # should be v1.6.1 or later

Authoring a Policy Pack

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

   mkdir policypack && cd policypack
   

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.

   macOS or Linux: You can run export PULUMI_EXPERIMENTAL=true or simply prepend it to your commands as shown.

   PULUMI_EXPERIMENTAL=true pulumi policy new aws-typescript
   

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

   Windows cmd.exe

   set PULUMI_EXPERIMENTAL=true
   pulumi policy new aws-typescript
   

   Windows PowerShell

   $env:PULUMI_EXPERIMENTAL = 'true'
   pulumi policy new aws-typescript
   

3. Tweak the Policy Pack in the index.ts file as desired. The existing policy in the template (which is annotated below) mandates that an AWS S3 bucket not have public read or write permissions enabled. Each Policy must have a unique name, an enforcement level, and a validation function. Here we use validateResourceOfType that allows us to validate S3 Bucket resources.

   // Create a new Policy Pack.
   new PolicyPack("policy-pack-typescript", {
       // Specify the Policies in the Policy Pack.
       policies: [{
           // The name for the Policy must be unique within the Pack.
           name: "s3-no-public-read",
   
           // The description should document what the Policy does and why it exists.
           description: "Prohibits setting the publicRead or publicReadWrite permission on AWS S3 buckets.",
   
           // The enforcement level can either be "advisory" or "mandatory". An "advisory" enforcement level
           // simply prints a warning for users, while a "mandatory" policy will block an update from proceeding.
           enforcementLevel: "mandatory",
   
           // The validateResourceOfType function allows you to filter resources. In this case, the rule only
           // applies to S3 buckets and reports a violation if the acl is "public-read" or "public-read-write".
           validateResource: validateResourceOfType(aws.s3.Bucket, (bucket, args, reportViolation) => {
               if (bucket.acl === "public-read" || bucket.acl === "public-read-write") {
                   reportViolation(
                       "You cannot set public-read or public-read-write on an S3 bucket. " +
                       "Read more about ACLs here: https://docs.aws.amazon.com/AmazonS3/latest/dev/acl-overview.html");
               }
           }),
       }],
   });
   

You can find more example Policy Packs in the examples repo. Best practices for writing a Policy Pack can be found here.

Test the new Policy Pack

Policy Packs can be tested on a user's local workstation to facilitate rapid development and testing of policies. This removes the step of publishing and applying policy packs to the Pulumi Console and lets developers reference a policy pack on their local workstation.

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 project.

   If you don’t have a Pulumi project 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:

   macOS or Linux:

   PULUMI_DEBUG_COMMANDS=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 in compliance, we expect the output to simply tell us which Policy Packs were run.

   Previewing update (dev):
   
       Type                 Name          Plan
   +   pulumi:pulumi:Stack  test-dev  	create
   +   └─ aws:s3:Bucket     my-bucket     create
   
   Resources:
       + 2 to create
   

3. We can then edit the stack code to specify the ACL to be public-read.

   const bucket = new aws.s3.Bucket("my-bucket", {
       acl: "public-read",
   });
   

4. We then run the pulumi preview command again and this time get an error message indicating we failed the preview because of a policy violation.

   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-no-public-read] Prohibits setting the publicRead or publicReadWrite permission on AWS S3 buckets.
       You cannot set public-read or public-read-write on an S3 bucket. Read more about ACLs here: https://docs.aws.amazon.com/AmazonS3/latest/dev/acl-overview.html
   

Best Practices for Writing Policies

Naming Policies

Each policy within a Policy Pack must have a unique name. The name must be between 1 and 100 characters and may contain letters, numbers, dashes (-), underscores (_) or periods(.).

Policy Assertions

Policy assertions should be complete sentences, specify the resource that has violated the policy, and be written using an imperative tone. The table below provides some examples of policy assertions.

✅	❌
"The RDS cluster must specify a node type."	"Specify a node type."
"The RDS cluster must have audit logging enabled."	"Enable audit logging."

This format provides a clear message to end users, allowing them to understand what and why a policy is failing.