Azure Policy Overview

Introduction to Azure Policy

Azure Policy is a service in Azure that helps you enforce organizational standards and assess compliance at scale. It provides a unified way to manage and prevent compliance issues. With Policy, you can provision resources that are compliant and remediate non-compliant resources. Azure Policy is a powerful tool for enterprises to maintain governance and control over their Azure environments.

It is crucial for maintaining a secure, cost-effective, and well-governed cloud infrastructure. By defining and enforcing rules across your Azure resources, you can ensure that your deployments align with your organization's policies and industry regulations.

Key Concepts

• Policy Definition: A rule that specifies a condition and a set of effects if the condition is met. Definitions are often written in JSON.
• Policy Assignment: The act of applying a policy definition to a specific scope (e.g., management group, subscription, resource group).
• Initiative Definition (Policy Set): A collection of policy definitions that are grouped together to achieve a larger goal.
• Effect: The action taken when a policy rule is evaluated. Common effects include 'Deny', 'Audit', 'Append', 'Modify', 'DeployIfNotExists', and 'AuditIfNotExists'.
• Scope: The level at which a policy is applied. This can range from a management group down to a resource group.
• Resource Group: A logical container for Azure resources.

How Azure Policy Works

Azure Policy evaluates resources in Azure by comparing the properties of those resources to the conditions defined in a policy rule. The evaluation occurs when a resource is created or updated, or periodically for existing resources.

Evaluation Process:

1. When a resource is deployed or updated, Azure Policy evaluates the resource against all applicable policy assignments.
2. If the resource properties match the conditions in a policy rule, the specified 'effect' is triggered.
3. For example, if a policy is assigned to deny the creation of virtual machines with insecure operating system configurations, and a user attempts to deploy such a VM, the 'Deny' effect will prevent the deployment.
4. If a policy is assigned to audit non-compliant resources, Azure Policy will log the non-compliance status without preventing the action.

Common Use Cases

• Resource Consistency: Enforcing standards like requiring tags on all resources.
• Security Compliance: Ensuring network security groups are configured correctly, or that only specific VM images are used.
• Cost Management: Restricting the types of resources that can be deployed to prevent unauthorized or expensive deployments.
• Governance: Implementing naming conventions, location restrictions, or resource type limitations.

Example: Enforcing Tags

A common policy assignment is to ensure that all resources have specific tags applied. This is crucial for cost tracking and resource management.

Policy Definition Snippet (JSON):

let tagName = "Environment";
let tagValue = "Production";

if (!resource.tags[tagName] || resource.tags[tagName] !== tagValue) {
  then {
    effect: "Audit";
  }
}

This example demonstrates a policy that audits resources if they do not have the 'Environment' tag set to 'Production'. You can change the effect to 'Deny' to prevent non-compliant resource creation.

Getting Started with Azure Policy

You can manage Azure Policy through the Azure portal, Azure CLI, Azure PowerShell, or ARM templates. Begin by defining your governance requirements and then creating policy definitions and assignments accordingly.

Explore the Azure Policy documentation for pre-defined policies and custom policy creation guidance. Implementing Azure Policy is a fundamental step towards robust cloud governance and compliance.