Terraform Module Refactoring: Azure Application Insights Web Tests

Infrastructure Stability Refactoring

Problem Solved: A production Terraform module managing Azure Application Insights web tests suffered from unintended infrastructure recreation, causing potential service outages when configuration lists were reordered.

Root Cause: The module used count for resource iteration, where resources were identified by their position in a list. Any change to list order (adding/removing items, reordering) triggered destroy-and-recreate operations for all subsequent resources.

Solution Implemented

Refactoring Approach:

Migrated from count to for_each with stable map keys
Redesigned input variables from lists to maps for consistent resource identity
Map keys became the single source of truth for resource naming and referencing

Key Changes:

Input variables: list(object) → map(object)
Resource iteration: count = length(var.items) → for_each = var.items
Resource naming: Index-based → Key-based identifiers

Impact & Results

Infrastructure Stability:

Eliminated unexpected resource recreation during configuration updates
Reduced production outage risk from infrastructure changes
Enabled safe, predictable Terraform deployments

Operational Benefits:

Simplified web test management and modifications
Improved deployment reliability and confidence
Enhanced infrastructure change management processes

Technologies & Tools

Terraform: Infrastructure as Code framework
Azure Application Insights: Web test monitoring service
Azure Cloud: Target infrastructure platform
Git: Version control for module and documentation
Semantic Versioning: Module release management

Project Scope

Module Components Refactored:

Web test resources and configurations
Alert rules and action groups
Input validation and type constraints
Output structures and data flow

Supporting Work:

Complete documentation rewrite
Usage examples and migration guides
Comprehensive testing strategy
Major version release with breaking change communication