Managing Azure Firewall rules, Network Security Group (NSG) rules, and route tables can quickly become complex—especially when working at scale and using Infrastructure as Code (IaC) tools like Terraform. As the number of rules grows, so does the management overhead, making it challenging to maintain clean, auditable, and easily modifiable configurations. In this blog, I’ll share a streamlined approach to managing these Azure resources efficiently using Terraform resource blocks and CSV files. This method not only reduces manual effort but also keeps your codebase clean and maintainable.
Why Use Terraform and CSV for Azure Rule Management?
When handling numerous input rules—often sourced from locals or auto.tfvars files—Terraform configurations can become unwieldy. By leveraging CSV files for rule definitions and automating their integration with Terraform, you can:
- Reduce code clutter: Keep your Terraform files concise, regardless of the number of rules.
- Simplify updates: Modify rules in bulk by editing a CSV, rather than multiple code blocks.
- Enhance visibility: Use Visual Studio Code extensions like Edit CSV or Rainbow CSV for easy rule inspection and editing.
Implementation Overview
- Structuring Input Rules
Define your Azure Firewall, NSG, and route table rules in CSV files. Each row represents a rule, making it easy to add, remove, or update entries as requirements change.
- Integrating with Terraform
Use Terraform resource blocks to read and process these CSV files. This approach allows you to dynamically generate the necessary Azure resources based on the CSV content, minimizing repetitive code.
- Visual Studio Code Extensions
To further streamline your workflow, consider using VS Code extensions such as:
- Edit CSV: For quick, spreadsheet-like editing.
- Rainbow CSV: For color-coded columns, making large files easier to read.
Example: Clean and Investigable Code
Below are snippets illustrating how this approach leads to cleaner, more maintainable code:
Azure Firewall Rules:
Network Security Group Rules:
Azure Route Table:
Resources
For ready-to-use Terraform modules and examples, check out these GitHub repositories:
- abshaw01/terraform-azurerm-firewall-policy-rule-collection-group
- abshaw01/terraform-azurerm-network-security-group
- abshaw01/terraform-azurerm-route-table
Conclusion
By combining Terraform with CSV-driven rule management, you can efficiently handle Azure Firewall, NSG, and route table rules at any scale. This approach not only reduces management overhead but also ensures your infrastructure remains clean, auditable, and easy to update.
Microsoft